Using derby to parse an SQL statement
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Using derby to parse an SQL statement
by Christian Riedel
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Hi there,
we are working on a small project where we need to analyze an SQL statement that can be of any kind: very simple, with inner selects, complex join etc. We figured it inappropriate to start to write our own parser when there are other projects, like derby, out there that can do it much better than we would possibly do ... so this was our idea: Can we use derby to create an instance of Parser (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL statement be parsed by calling the parse() method on this instance? What we want to have is a syntax tree of the statement that allows us to see which tables and which fields are accessed / included in the statement (including any possibly done "renames" á la SELECT street AS "ADDRESS" FROM USER_DATA ). The problem is, that we are stuck ... we spent several days now to try to find the proper way to create an instance of the Parser. Is it possible at all without having to set up a running derby system? Is the Monitor class the right entry point? How can we create a CompilerContext so that a Parser instance can be created? This sure is off-topic but we don't see any way through all this. Can you help us? Thanks in advance Christian -- To reply to this posting directly use the following address and remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... |
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Re: Using derby to parse an SQL statement
by Rick Hillegas-2
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Hi Christian,
I think you will have difficulty isolating the Parser from the rest of the SQL interpreter. In theory, you should be able to isolate the compiler from the execution engine and the storage layer--but that is an untested theory. The Parser wants to turn out abstract syntax trees (AST). Ideally, the Parser would just need to ask a NodeFactory for AST nodes and you could supply your own NodeFactory. But I think that there is a fair amount of coupling between the Parser and Derby's concrete implementation of NodeFactory. I think that you could uncouple the two, but you may not want to spend your time on that. So the Parser is going to force you to pull in the AST nodes. Once you do that, you will end up with the whole compiler. In particular, the AST nodes (and the Parser itself) expect that you will supply an implementation of LanguageConnectionContext, the master state variable for the whole SQL interpreter. Untangling that requirement is another chunk of work you may not want to do. Then there is the Monitor. It has been a while since I was in that code but I seem to recall that fairly early on the Monitor wants to fault in a storage layer. In theory you ought to be able to supply the Monitor a list of modules that doesn't include a storage layer. But since no-one runs in this configuration, there are probably a lot of undocumented surprises that you may not want to fix either. Can I ask you what breaks if you just pull in the whole Derby engine? Are you concerned that you will fault in too much code that you barely use? Are you concerned that you'll end up with a dummy database that you don't need? Are Derby's AST nodes not a usable representation of statement syntax? Thanks, -Rick Christian Riedel wrote: > Hi there, > > we are working on a small project where we need to analyze an SQL > statement that can be of any kind: very simple, with inner selects, > complex join etc. > > We figured it inappropriate to start to write our own parser when > there are other projects, like derby, out there that can do it much > better than we would possibly do ... so this was our idea: > > Can we use derby to create an instance of Parser > (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL > statement be parsed by calling the parse() method on this instance? > What we want to have is a syntax tree of the statement that allows us > to see which tables and which fields are accessed / included in the > statement (including any possibly done "renames" á la SELECT street AS > "ADDRESS" FROM USER_DATA ). > > The problem is, that we are stuck ... we spent several days now to try > to find the proper way to create an instance of the Parser. Is it > possible at all without having to set up a running derby system? > > Is the Monitor class the right entry point? How can we create a > CompilerContext so that a Parser instance can be created? > > > This sure is off-topic but we don't see any way through all this. Can > you help us? > > > Thanks in advance > > Christian > |
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Re: Using derby to parse an SQL statement
by Christian Riedel
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Hi Rick,
first of all thanks for your answer ... now the relations have become a lot clearer ... Your are right, there is a lot of things to be done that we probably don't want to go through. You asked why we cannot take the whole derby engine and use it ... well there is nor real reason not to do so. The only "problem" I see is, that derby is a dbms - if I am not mistaken - and we only have an SQL statement that we extract from a text file and want tot analyze it to extract some metadata from it. So if we take the derby engine as it is, how can I prevent that we have to set up a "dummy" DB in order to be able to actually use thje parsing feature .... I hope you see my point. We could live with setting up a dummy DB ... and I do think that the derby AST offers all information we need. It's just that I don't see how we can set this thing up. So having a dummy DB is necessary to be able to intercept the parsing process to get hold of the AST? Can we actually access the AST if we choose to set up a dummy DB? I think that would be something we could live with ;-) Thanks for your support Christian Rick Hillegas schrieb: > Hi Christian, > > I think you will have difficulty isolating the Parser from the rest of > the SQL interpreter. In theory, you should be able to isolate the > compiler from the execution engine and the storage layer--but that is an > untested theory. > > The Parser wants to turn out abstract syntax trees (AST). Ideally, the > Parser would just need to ask a NodeFactory for AST nodes and you could > supply your own NodeFactory. But I think that there is a fair amount of > coupling between the Parser and Derby's concrete implementation of > NodeFactory. I think that you could uncouple the two, but you may not > want to spend your time on that. > > So the Parser is going to force you to pull in the AST nodes. Once you > do that, you will end up with the whole compiler. In particular, the AST > nodes (and the Parser itself) expect that you will supply an > implementation of LanguageConnectionContext, the master state variable > for the whole SQL interpreter. Untangling that requirement is another > chunk of work you may not want to do. > > Then there is the Monitor. It has been a while since I was in that code > but I seem to recall that fairly early on the Monitor wants to fault in > a storage layer. In theory you ought to be able to supply the Monitor a > list of modules that doesn't include a storage layer. But since no-one > runs in this configuration, there are probably a lot of undocumented > surprises that you may not want to fix either. > > Can I ask you what breaks if you just pull in the whole Derby engine? > Are you concerned that you will fault in too much code that you barely > use? Are you concerned that you'll end up with a dummy database that you > don't need? Are Derby's AST nodes not a usable representation of > statement syntax? > > Thanks, > -Rick > > Christian Riedel wrote: >> Hi there, >> >> we are working on a small project where we need to analyze an SQL >> statement that can be of any kind: very simple, with inner selects, >> complex join etc. >> >> We figured it inappropriate to start to write our own parser when >> there are other projects, like derby, out there that can do it much >> better than we would possibly do ... so this was our idea: >> >> Can we use derby to create an instance of Parser >> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >> statement be parsed by calling the parse() method on this instance? >> What we want to have is a syntax tree of the statement that allows us >> to see which tables and which fields are accessed / included in the >> statement (including any possibly done "renames" á la SELECT street AS >> "ADDRESS" FROM USER_DATA ). >> >> The problem is, that we are stuck ... we spent several days now to try >> to find the proper way to create an instance of the Parser. Is it >> possible at all without having to set up a running derby system? >> >> Is the Monitor class the right entry point? How can we create a >> CompilerContext so that a Parser instance can be created? >> >> >> This sure is off-topic but we don't see any way through all this. Can >> you help us? >> >> >> Thanks in advance >> >> Christian >> > > -- To reply to this posting directly use the following address and remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... |
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Re: Using derby to parse an SQL statement
by Kristian Waagan-4
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Christian Riedel wrote:
> Hi Rick, > > first of all thanks for your answer ... now the relations have become > a lot clearer ... > > Your are right, there is a lot of things to be done that we probably > don't want to go through. You asked why we cannot take the whole derby > engine and use it ... well there is nor real reason not to do so. The > only "problem" I see is, that derby is a dbms - if I am not mistaken - > and we only have an SQL statement that we extract from a text file and > want tot analyze it to extract some metadata from it. > > So if we take the derby engine as it is, how can I prevent that we > have to set up a "dummy" DB in order to be able to actually use thje > parsing feature .... Hello, Note sure if it helps, but Derby does offer a storeless engine. I don't know if you can extract the AST with a little hacking, but it might be worth further investigation. Also, I don't know at which time it throws the exception about missing tables etc. Just as an example, you can write things like "values 1+4", but as if you write "select * from a", you get an error message saying a doesn't exist. I don't know what the internal state of Derby looks like at this point. regards, -- Kristian > > I hope you see my point. > > We could live with setting up a dummy DB ... and I do think that the > derby AST offers all information we need. It's just that I don't see > how we can set this thing up. So having a dummy DB is necessary to be > able to intercept the parsing process to get hold of the AST? Can we > actually access the AST if we choose to set up a dummy DB? I think > that would be something we could live with ;-) > > > Thanks for your support > > Christian > > > Rick Hillegas schrieb: >> Hi Christian, >> >> I think you will have difficulty isolating the Parser from the rest >> of the SQL interpreter. In theory, you should be able to isolate the >> compiler from the execution engine and the storage layer--but that is >> an untested theory. >> >> The Parser wants to turn out abstract syntax trees (AST). Ideally, >> the Parser would just need to ask a NodeFactory for AST nodes and you >> could supply your own NodeFactory. But I think that there is a fair >> amount of coupling between the Parser and Derby's concrete >> implementation of NodeFactory. I think that you could uncouple the >> two, but you may not want to spend your time on that. >> >> So the Parser is going to force you to pull in the AST nodes. Once >> you do that, you will end up with the whole compiler. In particular, >> the AST nodes (and the Parser itself) expect that you will supply an >> implementation of LanguageConnectionContext, the master state >> variable for the whole SQL interpreter. Untangling that requirement >> is another chunk of work you may not want to do. >> >> Then there is the Monitor. It has been a while since I was in that >> code but I seem to recall that fairly early on the Monitor wants to >> fault in a storage layer. In theory you ought to be able to supply >> the Monitor a list of modules that doesn't include a storage layer. >> But since no-one runs in this configuration, there are probably a lot >> of undocumented surprises that you may not want to fix either. >> >> Can I ask you what breaks if you just pull in the whole Derby engine? >> Are you concerned that you will fault in too much code that you >> barely use? Are you concerned that you'll end up with a dummy >> database that you don't need? Are Derby's AST nodes not a usable >> representation of statement syntax? >> >> Thanks, >> -Rick >> >> Christian Riedel wrote: >>> Hi there, >>> >>> we are working on a small project where we need to analyze an SQL >>> statement that can be of any kind: very simple, with inner selects, >>> complex join etc. >>> >>> We figured it inappropriate to start to write our own parser when >>> there are other projects, like derby, out there that can do it much >>> better than we would possibly do ... so this was our idea: >>> >>> Can we use derby to create an instance of Parser >>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>> statement be parsed by calling the parse() method on this instance? >>> What we want to have is a syntax tree of the statement that allows >>> us to see which tables and which fields are accessed / included in >>> the statement (including any possibly done "renames" á la SELECT >>> street AS "ADDRESS" FROM USER_DATA ). >>> >>> The problem is, that we are stuck ... we spent several days now to >>> try to find the proper way to create an instance of the Parser. Is >>> it possible at all without having to set up a running derby system? >>> >>> Is the Monitor class the right entry point? How can we create a >>> CompilerContext so that a Parser instance can be created? >>> >>> >>> This sure is off-topic but we don't see any way through all this. >>> Can you help us? >>> >>> >>> Thanks in advance >>> >>> Christian >>> >> >> > |
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Re: Using derby to parse an SQL statement
by Mamta Satoor
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I am pretty sure the exceptions for missing tables etc are thrown in
the bind phase which comes after the parsing phase. Mamta On Wed, Nov 12, 2008 at 8:11 AM, Kristian Waagan <Kristian.Waagan@...> wrote: > Christian Riedel wrote: >> >> Hi Rick, >> >> first of all thanks for your answer ... now the relations have become a >> lot clearer ... >> >> Your are right, there is a lot of things to be done that we probably don't >> want to go through. You asked why we cannot take the whole derby engine and >> use it ... well there is nor real reason not to do so. The only "problem" I >> see is, that derby is a dbms - if I am not mistaken - and we only have an >> SQL statement that we extract from a text file and want tot analyze it to >> extract some metadata from it. >> >> So if we take the derby engine as it is, how can I prevent that we have to >> set up a "dummy" DB in order to be able to actually use thje parsing feature >> .... > > Hello, > > Note sure if it helps, but Derby does offer a storeless engine. I don't know > if you can extract the AST with a little hacking, but it might be worth > further investigation. Also, I don't know at which time it throws the > exception about missing tables etc. > > Just as an example, you can write things like "values 1+4", but as if you > write "select * from a", you get an error message saying a doesn't exist. I > don't know what the internal state of Derby looks like at this point. > > > regards, > -- > Kristian > >> >> I hope you see my point. >> >> We could live with setting up a dummy DB ... and I do think that the derby >> AST offers all information we need. It's just that I don't see how we can >> set this thing up. So having a dummy DB is necessary to be able to intercept >> the parsing process to get hold of the AST? Can we actually access the AST >> if we choose to set up a dummy DB? I think that would be something we could >> live with ;-) >> >> >> Thanks for your support >> >> Christian >> >> >> Rick Hillegas schrieb: >>> >>> Hi Christian, >>> >>> I think you will have difficulty isolating the Parser from the rest of >>> the SQL interpreter. In theory, you should be able to isolate the compiler >>> from the execution engine and the storage layer--but that is an untested >>> theory. >>> >>> The Parser wants to turn out abstract syntax trees (AST). Ideally, the >>> Parser would just need to ask a NodeFactory for AST nodes and you could >>> supply your own NodeFactory. But I think that there is a fair amount of >>> coupling between the Parser and Derby's concrete implementation of >>> NodeFactory. I think that you could uncouple the two, but you may not want >>> to spend your time on that. >>> >>> So the Parser is going to force you to pull in the AST nodes. Once you do >>> that, you will end up with the whole compiler. In particular, the AST nodes >>> (and the Parser itself) expect that you will supply an implementation of >>> LanguageConnectionContext, the master state variable for the whole SQL >>> interpreter. Untangling that requirement is another chunk of work you may >>> not want to do. >>> >>> Then there is the Monitor. It has been a while since I was in that code >>> but I seem to recall that fairly early on the Monitor wants to fault in a >>> storage layer. In theory you ought to be able to supply the Monitor a list >>> of modules that doesn't include a storage layer. But since no-one runs in >>> this configuration, there are probably a lot of undocumented surprises that >>> you may not want to fix either. >>> >>> Can I ask you what breaks if you just pull in the whole Derby engine? Are >>> you concerned that you will fault in too much code that you barely use? Are >>> you concerned that you'll end up with a dummy database that you don't need? >>> Are Derby's AST nodes not a usable representation of statement syntax? >>> >>> Thanks, >>> -Rick >>> >>> Christian Riedel wrote: >>>> >>>> Hi there, >>>> >>>> we are working on a small project where we need to analyze an SQL >>>> statement that can be of any kind: very simple, with inner selects, complex >>>> join etc. >>>> >>>> We figured it inappropriate to start to write our own parser when there >>>> are other projects, like derby, out there that can do it much better than we >>>> would possibly do ... so this was our idea: >>>> >>>> Can we use derby to create an instance of Parser >>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL statement >>>> be parsed by calling the parse() method on this instance? What we want to >>>> have is a syntax tree of the statement that allows us to see which tables >>>> and which fields are accessed / included in the statement (including any >>>> possibly done "renames" á la SELECT street AS "ADDRESS" FROM USER_DATA ). >>>> >>>> The problem is, that we are stuck ... we spent several days now to try >>>> to find the proper way to create an instance of the Parser. Is it possible >>>> at all without having to set up a running derby system? >>>> >>>> Is the Monitor class the right entry point? How can we create a >>>> CompilerContext so that a Parser instance can be created? >>>> >>>> >>>> This sure is off-topic but we don't see any way through all this. Can >>>> you help us? >>>> >>>> >>>> Thanks in advance >>>> >>>> Christian >>>> >>> >>> >> > > |
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Re: Using derby to parse an SQL statement
by francois.orsini
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Dan had posted some interesting suggestion here as well:
http://www.nabble.com/Use-SQL-parsing-to7595059.html#a7638751
On Wed, Nov 12, 2008 at 8:11 AM, Kristian Waagan <Kristian.Waagan@...> wrote:
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Re: Using derby to parse an SQL statement
by Rick Hillegas-2
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Hi Christian,
Standby. I will post some code showing how to do this later today. Cheers, -Rick Christian Riedel wrote: > Hi Rick, > > first of all thanks for your answer ... now the relations have become > a lot clearer ... > > Your are right, there is a lot of things to be done that we probably > don't want to go through. You asked why we cannot take the whole derby > engine and use it ... well there is nor real reason not to do so. The > only "problem" I see is, that derby is a dbms - if I am not mistaken - > and we only have an SQL statement that we extract from a text file and > want tot analyze it to extract some metadata from it. > > So if we take the derby engine as it is, how can I prevent that we > have to set up a "dummy" DB in order to be able to actually use thje > parsing feature .... > > I hope you see my point. > > We could live with setting up a dummy DB ... and I do think that the > derby AST offers all information we need. It's just that I don't see > how we can set this thing up. So having a dummy DB is necessary to be > able to intercept the parsing process to get hold of the AST? Can we > actually access the AST if we choose to set up a dummy DB? I think > that would be something we could live with ;-) > > > Thanks for your support > > Christian > > > Rick Hillegas schrieb: >> Hi Christian, >> >> I think you will have difficulty isolating the Parser from the rest >> of the SQL interpreter. In theory, you should be able to isolate the >> compiler from the execution engine and the storage layer--but that is >> an untested theory. >> >> The Parser wants to turn out abstract syntax trees (AST). Ideally, >> the Parser would just need to ask a NodeFactory for AST nodes and you >> could supply your own NodeFactory. But I think that there is a fair >> amount of coupling between the Parser and Derby's concrete >> implementation of NodeFactory. I think that you could uncouple the >> two, but you may not want to spend your time on that. >> >> So the Parser is going to force you to pull in the AST nodes. Once >> you do that, you will end up with the whole compiler. In particular, >> the AST nodes (and the Parser itself) expect that you will supply an >> implementation of LanguageConnectionContext, the master state >> variable for the whole SQL interpreter. Untangling that requirement >> is another chunk of work you may not want to do. >> >> Then there is the Monitor. It has been a while since I was in that >> code but I seem to recall that fairly early on the Monitor wants to >> fault in a storage layer. In theory you ought to be able to supply >> the Monitor a list of modules that doesn't include a storage layer. >> But since no-one runs in this configuration, there are probably a lot >> of undocumented surprises that you may not want to fix either. >> >> Can I ask you what breaks if you just pull in the whole Derby engine? >> Are you concerned that you will fault in too much code that you >> barely use? Are you concerned that you'll end up with a dummy >> database that you don't need? Are Derby's AST nodes not a usable >> representation of statement syntax? >> >> Thanks, >> -Rick >> >> Christian Riedel wrote: >>> Hi there, >>> >>> we are working on a small project where we need to analyze an SQL >>> statement that can be of any kind: very simple, with inner selects, >>> complex join etc. >>> >>> We figured it inappropriate to start to write our own parser when >>> there are other projects, like derby, out there that can do it much >>> better than we would possibly do ... so this was our idea: >>> >>> Can we use derby to create an instance of Parser >>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>> statement be parsed by calling the parse() method on this instance? >>> What we want to have is a syntax tree of the statement that allows >>> us to see which tables and which fields are accessed / included in >>> the statement (including any possibly done "renames" á la SELECT >>> street AS "ADDRESS" FROM USER_DATA ). >>> >>> The problem is, that we are stuck ... we spent several days now to >>> try to find the proper way to create an instance of the Parser. Is >>> it possible at all without having to set up a running derby system? >>> >>> Is the Monitor class the right entry point? How can we create a >>> CompilerContext so that a Parser instance can be created? >>> >>> >>> This sure is off-topic but we don't see any way through all this. >>> Can you help us? >>> >>> >>> Thanks in advance >>> >>> Christian >>> >> >> > |
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Re: Using derby to parse an SQL statement
by Rick Hillegas-2
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Hi Christian,
I have created a JIRA to track this issue: https://issues.apache.org/jira/browse/DERBY-3946 I have attached to the JIRA a small patch which exposes the AST produced by the parser. I have also attached a simple program, ASTParser, which shows how to retrieve the AST from Derby. I am inclined to check this patch in to the trunk. Please let me know if you find this useful and if you would like me to port this patch to another Derby branch. Hope this helps, -Rick Christian Riedel wrote: > Hi Rick, > > first of all thanks for your answer ... now the relations have become > a lot clearer ... > > Your are right, there is a lot of things to be done that we probably > don't want to go through. You asked why we cannot take the whole derby > engine and use it ... well there is nor real reason not to do so. The > only "problem" I see is, that derby is a dbms - if I am not mistaken - > and we only have an SQL statement that we extract from a text file and > want tot analyze it to extract some metadata from it. > > So if we take the derby engine as it is, how can I prevent that we > have to set up a "dummy" DB in order to be able to actually use thje > parsing feature .... > > I hope you see my point. > > We could live with setting up a dummy DB ... and I do think that the > derby AST offers all information we need. It's just that I don't see > how we can set this thing up. So having a dummy DB is necessary to be > able to intercept the parsing process to get hold of the AST? Can we > actually access the AST if we choose to set up a dummy DB? I think > that would be something we could live with ;-) > > > Thanks for your support > > Christian > > > Rick Hillegas schrieb: >> Hi Christian, >> >> I think you will have difficulty isolating the Parser from the rest >> of the SQL interpreter. In theory, you should be able to isolate the >> compiler from the execution engine and the storage layer--but that is >> an untested theory. >> >> The Parser wants to turn out abstract syntax trees (AST). Ideally, >> the Parser would just need to ask a NodeFactory for AST nodes and you >> could supply your own NodeFactory. But I think that there is a fair >> amount of coupling between the Parser and Derby's concrete >> implementation of NodeFactory. I think that you could uncouple the >> two, but you may not want to spend your time on that. >> >> So the Parser is going to force you to pull in the AST nodes. Once >> you do that, you will end up with the whole compiler. In particular, >> the AST nodes (and the Parser itself) expect that you will supply an >> implementation of LanguageConnectionContext, the master state >> variable for the whole SQL interpreter. Untangling that requirement >> is another chunk of work you may not want to do. >> >> Then there is the Monitor. It has been a while since I was in that >> code but I seem to recall that fairly early on the Monitor wants to >> fault in a storage layer. In theory you ought to be able to supply >> the Monitor a list of modules that doesn't include a storage layer. >> But since no-one runs in this configuration, there are probably a lot >> of undocumented surprises that you may not want to fix either. >> >> Can I ask you what breaks if you just pull in the whole Derby engine? >> Are you concerned that you will fault in too much code that you >> barely use? Are you concerned that you'll end up with a dummy >> database that you don't need? Are Derby's AST nodes not a usable >> representation of statement syntax? >> >> Thanks, >> -Rick >> >> Christian Riedel wrote: >>> Hi there, >>> >>> we are working on a small project where we need to analyze an SQL >>> statement that can be of any kind: very simple, with inner selects, >>> complex join etc. >>> >>> We figured it inappropriate to start to write our own parser when >>> there are other projects, like derby, out there that can do it much >>> better than we would possibly do ... so this was our idea: >>> >>> Can we use derby to create an instance of Parser >>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>> statement be parsed by calling the parse() method on this instance? >>> What we want to have is a syntax tree of the statement that allows >>> us to see which tables and which fields are accessed / included in >>> the statement (including any possibly done "renames" á la SELECT >>> street AS "ADDRESS" FROM USER_DATA ). >>> >>> The problem is, that we are stuck ... we spent several days now to >>> try to find the proper way to create an instance of the Parser. Is >>> it possible at all without having to set up a running derby system? >>> >>> Is the Monitor class the right entry point? How can we create a >>> CompilerContext so that a Parser instance can be created? >>> >>> >>> This sure is off-topic but we don't see any way through all this. >>> Can you help us? >>> >>> >>> Thanks in advance >>> >>> Christian >>> >> >> > |
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Re: Using derby to parse an SQL statement
by Christian Riedel
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Hi Rick,
at first thank you very much for your efforts so far. At a first glance your changes to the code seem to be exactly what we want. I will try if it works asap. To test it with the derby libs I'd have to work on the current trunk and apply the patch an then compile derby manually, right? I'll keep you updated Thanks for your help Christian Rick Hillegas schrieb: > Hi Christian, > > I have created a JIRA to track this issue: > https://issues.apache.org/jira/browse/DERBY-3946 > > I have attached to the JIRA a small patch which exposes the AST produced > by the parser. I have also attached a simple program, ASTParser, which > shows how to retrieve the AST from Derby. I am inclined to check this > patch in to the trunk. Please let me know if you find this useful and if > you would like me to port this patch to another Derby branch. > > Hope this helps, > -Rick > > Christian Riedel wrote: >> Hi Rick, >> >> first of all thanks for your answer ... now the relations have become >> a lot clearer ... >> >> Your are right, there is a lot of things to be done that we probably >> don't want to go through. You asked why we cannot take the whole derby >> engine and use it ... well there is nor real reason not to do so. The >> only "problem" I see is, that derby is a dbms - if I am not mistaken - >> and we only have an SQL statement that we extract from a text file and >> want tot analyze it to extract some metadata from it. >> >> So if we take the derby engine as it is, how can I prevent that we >> have to set up a "dummy" DB in order to be able to actually use thje >> parsing feature .... >> >> I hope you see my point. >> >> We could live with setting up a dummy DB ... and I do think that the >> derby AST offers all information we need. It's just that I don't see >> how we can set this thing up. So having a dummy DB is necessary to be >> able to intercept the parsing process to get hold of the AST? Can we >> actually access the AST if we choose to set up a dummy DB? I think >> that would be something we could live with ;-) >> >> >> Thanks for your support >> >> Christian >> >> >> Rick Hillegas schrieb: >>> Hi Christian, >>> >>> I think you will have difficulty isolating the Parser from the rest >>> of the SQL interpreter. In theory, you should be able to isolate the >>> compiler from the execution engine and the storage layer--but that is >>> an untested theory. >>> >>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>> the Parser would just need to ask a NodeFactory for AST nodes and you >>> could supply your own NodeFactory. But I think that there is a fair >>> amount of coupling between the Parser and Derby's concrete >>> implementation of NodeFactory. I think that you could uncouple the >>> two, but you may not want to spend your time on that. >>> >>> So the Parser is going to force you to pull in the AST nodes. Once >>> you do that, you will end up with the whole compiler. In particular, >>> the AST nodes (and the Parser itself) expect that you will supply an >>> implementation of LanguageConnectionContext, the master state >>> variable for the whole SQL interpreter. Untangling that requirement >>> is another chunk of work you may not want to do. >>> >>> Then there is the Monitor. It has been a while since I was in that >>> code but I seem to recall that fairly early on the Monitor wants to >>> fault in a storage layer. In theory you ought to be able to supply >>> the Monitor a list of modules that doesn't include a storage layer. >>> But since no-one runs in this configuration, there are probably a lot >>> of undocumented surprises that you may not want to fix either. >>> >>> Can I ask you what breaks if you just pull in the whole Derby engine? >>> Are you concerned that you will fault in too much code that you >>> barely use? Are you concerned that you'll end up with a dummy >>> database that you don't need? Are Derby's AST nodes not a usable >>> representation of statement syntax? >>> >>> Thanks, >>> -Rick >>> >>> Christian Riedel wrote: >>>> Hi there, >>>> >>>> we are working on a small project where we need to analyze an SQL >>>> statement that can be of any kind: very simple, with inner selects, >>>> complex join etc. >>>> >>>> We figured it inappropriate to start to write our own parser when >>>> there are other projects, like derby, out there that can do it much >>>> better than we would possibly do ... so this was our idea: >>>> >>>> Can we use derby to create an instance of Parser >>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>> statement be parsed by calling the parse() method on this instance? >>>> What we want to have is a syntax tree of the statement that allows >>>> us to see which tables and which fields are accessed / included in >>>> the statement (including any possibly done "renames" á la SELECT >>>> street AS "ADDRESS" FROM USER_DATA ). >>>> >>>> The problem is, that we are stuck ... we spent several days now to >>>> try to find the proper way to create an instance of the Parser. Is >>>> it possible at all without having to set up a running derby system? >>>> >>>> Is the Monitor class the right entry point? How can we create a >>>> CompilerContext so that a Parser instance can be created? >>>> >>>> >>>> This sure is off-topic but we don't see any way through all this. >>>> Can you help us? >>>> >>>> >>>> Thanks in advance >>>> >>>> Christian >>>> >>> >>> >> > > -- To reply to this posting directly use the following address and remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... |
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R: Using derby to parse an SQL statement
by Flavio Palumbo
::
Rate this Message:
Hi guys,
I followed this post finding it very exciting, cause I post a similar question a while ago. Now I'd like to test the work submitted by Rick but I'm not so inside Derby to catch he whole job I have to do. I understood that I have to : - download Derby sources (from where ?) - apply the patch suggested by Rich (seen the classes but not catch the lines of code) - recompile Derby (what libraries/jars I need to) - use ASTParser as suggested Can somebody give me a hint ? Thanks a lot Flavio > -----Messaggio originale----- > Da: news [mailto:news@...]Per conto di Christian Riedel > Inviato: giovedì 13 novembre 2008 6.37 > A: derby-user@... > Oggetto: Re: Using derby to parse an SQL statement > > > Hi Rick, > > at first thank you very much for your efforts so far. At a first glance > your changes to the code seem to be exactly what we want. I will try if > it works asap. > > To test it with the derby libs I'd have to work on the current trunk and > apply the patch an then compile derby manually, right? > > I'll keep you updated > > Thanks for your help > > Christian > > Rick Hillegas schrieb: > > Hi Christian, > > > > I have created a JIRA to track this issue: > > https://issues.apache.org/jira/browse/DERBY-3946 > > > > I have attached to the JIRA a small patch which exposes the AST > produced > > by the parser. I have also attached a simple program, ASTParser, which > > shows how to retrieve the AST from Derby. I am inclined to check this > > patch in to the trunk. Please let me know if you find this > useful and if > > you would like me to port this patch to another Derby branch. > > > > Hope this helps, > > -Rick > > > > Christian Riedel wrote: > >> Hi Rick, > >> > >> first of all thanks for your answer ... now the relations have become > >> a lot clearer ... > >> > >> Your are right, there is a lot of things to be done that we probably > >> don't want to go through. You asked why we cannot take the whole derby > >> engine and use it ... well there is nor real reason not to do so. The > >> only "problem" I see is, that derby is a dbms - if I am not mistaken - > >> and we only have an SQL statement that we extract from a text file and > >> want tot analyze it to extract some metadata from it. > >> > >> So if we take the derby engine as it is, how can I prevent that we > >> have to set up a "dummy" DB in order to be able to actually use thje > >> parsing feature .... > >> > >> I hope you see my point. > >> > >> We could live with setting up a dummy DB ... and I do think that the > >> derby AST offers all information we need. It's just that I don't see > >> how we can set this thing up. So having a dummy DB is necessary to be > >> able to intercept the parsing process to get hold of the AST? Can we > >> actually access the AST if we choose to set up a dummy DB? I think > >> that would be something we could live with ;-) > >> > >> > >> Thanks for your support > >> > >> Christian > >> > >> > >> Rick Hillegas schrieb: > >>> Hi Christian, > >>> > >>> I think you will have difficulty isolating the Parser from the rest > >>> of the SQL interpreter. In theory, you should be able to isolate the > >>> compiler from the execution engine and the storage layer--but that is > >>> an untested theory. > >>> > >>> The Parser wants to turn out abstract syntax trees (AST). Ideally, > >>> the Parser would just need to ask a NodeFactory for AST nodes and you > >>> could supply your own NodeFactory. But I think that there is a fair > >>> amount of coupling between the Parser and Derby's concrete > >>> implementation of NodeFactory. I think that you could uncouple the > >>> two, but you may not want to spend your time on that. > >>> > >>> So the Parser is going to force you to pull in the AST nodes. Once > >>> you do that, you will end up with the whole compiler. In particular, > >>> the AST nodes (and the Parser itself) expect that you will supply an > >>> implementation of LanguageConnectionContext, the master state > >>> variable for the whole SQL interpreter. Untangling that requirement > >>> is another chunk of work you may not want to do. > >>> > >>> Then there is the Monitor. It has been a while since I was in that > >>> code but I seem to recall that fairly early on the Monitor wants to > >>> fault in a storage layer. In theory you ought to be able to supply > >>> the Monitor a list of modules that doesn't include a storage layer. > >>> But since no-one runs in this configuration, there are probably a lot > >>> of undocumented surprises that you may not want to fix either. > >>> > >>> Can I ask you what breaks if you just pull in the whole Derby engine? > >>> Are you concerned that you will fault in too much code that you > >>> barely use? Are you concerned that you'll end up with a dummy > >>> database that you don't need? Are Derby's AST nodes not a usable > >>> representation of statement syntax? > >>> > >>> Thanks, > >>> -Rick > >>> > >>> Christian Riedel wrote: > >>>> Hi there, > >>>> > >>>> we are working on a small project where we need to analyze an SQL > >>>> statement that can be of any kind: very simple, with inner selects, > >>>> complex join etc. > >>>> > >>>> We figured it inappropriate to start to write our own parser when > >>>> there are other projects, like derby, out there that can do it much > >>>> better than we would possibly do ... so this was our idea: > >>>> > >>>> Can we use derby to create an instance of Parser > >>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL > >>>> statement be parsed by calling the parse() method on this instance? > >>>> What we want to have is a syntax tree of the statement that allows > >>>> us to see which tables and which fields are accessed / included in > >>>> the statement (including any possibly done "renames" á la SELECT > >>>> street AS "ADDRESS" FROM USER_DATA ). > >>>> > >>>> The problem is, that we are stuck ... we spent several days now to > >>>> try to find the proper way to create an instance of the Parser. Is > >>>> it possible at all without having to set up a running derby system? > >>>> > >>>> Is the Monitor class the right entry point? How can we create a > >>>> CompilerContext so that a Parser instance can be created? > >>>> > >>>> > >>>> This sure is off-topic but we don't see any way through all this. > >>>> Can you help us? > >>>> > >>>> > >>>> Thanks in advance > >>>> > >>>> Christian > >>>> > >>> > >>> > >> > > > > > > -- > To reply to this posting directly use the following address and > remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... > ----------------------------------------------------------- Il presente messaggio non costituisce un impegno contrattuale tra SILMA S.r.l. ed il destinatario. Le opinioni ivi espresse sono quelle dell'autore. SILMA S.r.l. non assume alcuna responsabilita riguardo al contenuto del presente messaggio. Il messaggio è destinato esclusivamente al destinatario. Il contenuto e gli allegati sono da considerarsi di natura confidenziale Nel caso abbiate ricevuto il presente messaggio per errore siete pregati di comunicarlo alla casella segreteria@.... |
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Re: Using derby to parse an SQL statement
by Rick Hillegas-2
::
Rate this Message:
Hi Christian,
I have checked the patch into the development trunk. At this point, you will automatically get the fix if you build an up-to-date copy of the trunk. Please let us know what your experience is. You will notice from the discussion on the JIRA that some syntax may not work--this is because the separation between the parsing and name-resolution phases is not as clean as it should be. The JIRA would be a good place for you to record your observations. Thanks, -Rick Christian Riedel wrote: > Hi Rick, > > at first thank you very much for your efforts so far. At a first > glance your changes to the code seem to be exactly what we want. I > will try if it works asap. > > To test it with the derby libs I'd have to work on the current trunk > and apply the patch an then compile derby manually, right? > > I'll keep you updated > > Thanks for your help > > Christian > > Rick Hillegas schrieb: >> Hi Christian, >> >> I have created a JIRA to track this issue: >> https://issues.apache.org/jira/browse/DERBY-3946 >> >> I have attached to the JIRA a small patch which exposes the AST >> produced by the parser. I have also attached a simple program, >> ASTParser, which shows how to retrieve the AST from Derby. I am >> inclined to check this patch in to the trunk. Please let me know if >> you find this useful and if you would like me to port this patch to >> another Derby branch. >> >> Hope this helps, >> -Rick >> >> Christian Riedel wrote: >>> Hi Rick, >>> >>> first of all thanks for your answer ... now the relations have >>> become a lot clearer ... >>> >>> Your are right, there is a lot of things to be done that we probably >>> don't want to go through. You asked why we cannot take the whole >>> derby engine and use it ... well there is nor real reason not to do >>> so. The only "problem" I see is, that derby is a dbms - if I am not >>> mistaken - and we only have an SQL statement that we extract from a >>> text file and want tot analyze it to extract some metadata from it. >>> >>> So if we take the derby engine as it is, how can I prevent that we >>> have to set up a "dummy" DB in order to be able to actually use thje >>> parsing feature .... >>> >>> I hope you see my point. >>> >>> We could live with setting up a dummy DB ... and I do think that the >>> derby AST offers all information we need. It's just that I don't see >>> how we can set this thing up. So having a dummy DB is necessary to >>> be able to intercept the parsing process to get hold of the AST? Can >>> we actually access the AST if we choose to set up a dummy DB? I >>> think that would be something we could live with ;-) >>> >>> >>> Thanks for your support >>> >>> Christian >>> >>> >>> Rick Hillegas schrieb: >>>> Hi Christian, >>>> >>>> I think you will have difficulty isolating the Parser from the rest >>>> of the SQL interpreter. In theory, you should be able to isolate >>>> the compiler from the execution engine and the storage layer--but >>>> that is an untested theory. >>>> >>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>> the Parser would just need to ask a NodeFactory for AST nodes and >>>> you could supply your own NodeFactory. But I think that there is a >>>> fair amount of coupling between the Parser and Derby's concrete >>>> implementation of NodeFactory. I think that you could uncouple the >>>> two, but you may not want to spend your time on that. >>>> >>>> So the Parser is going to force you to pull in the AST nodes. Once >>>> you do that, you will end up with the whole compiler. In >>>> particular, the AST nodes (and the Parser itself) expect that you >>>> will supply an implementation of LanguageConnectionContext, the >>>> master state variable for the whole SQL interpreter. Untangling >>>> that requirement is another chunk of work you may not want to do. >>>> >>>> Then there is the Monitor. It has been a while since I was in that >>>> code but I seem to recall that fairly early on the Monitor wants to >>>> fault in a storage layer. In theory you ought to be able to supply >>>> the Monitor a list of modules that doesn't include a storage layer. >>>> But since no-one runs in this configuration, there are probably a >>>> lot of undocumented surprises that you may not want to fix either. >>>> >>>> Can I ask you what breaks if you just pull in the whole Derby >>>> engine? Are you concerned that you will fault in too much code that >>>> you barely use? Are you concerned that you'll end up with a dummy >>>> database that you don't need? Are Derby's AST nodes not a usable >>>> representation of statement syntax? >>>> >>>> Thanks, >>>> -Rick >>>> >>>> Christian Riedel wrote: >>>>> Hi there, >>>>> >>>>> we are working on a small project where we need to analyze an SQL >>>>> statement that can be of any kind: very simple, with inner >>>>> selects, complex join etc. >>>>> >>>>> We figured it inappropriate to start to write our own parser when >>>>> there are other projects, like derby, out there that can do it >>>>> much better than we would possibly do ... so this was our idea: >>>>> >>>>> Can we use derby to create an instance of Parser >>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>> statement be parsed by calling the parse() method on this >>>>> instance? What we want to have is a syntax tree of the statement >>>>> that allows us to see which tables and which fields are accessed / >>>>> included in the statement (including any possibly done "renames" á >>>>> la SELECT street AS "ADDRESS" FROM USER_DATA ). >>>>> >>>>> The problem is, that we are stuck ... we spent several days now to >>>>> try to find the proper way to create an instance of the Parser. Is >>>>> it possible at all without having to set up a running derby system? >>>>> >>>>> Is the Monitor class the right entry point? How can we create a >>>>> CompilerContext so that a Parser instance can be created? >>>>> >>>>> >>>>> This sure is off-topic but we don't see any way through all this. >>>>> Can you help us? >>>>> >>>>> >>>>> Thanks in advance >>>>> >>>>> Christian >>>>> >>>> >>>> >>> >> >> > |
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Re: R: Using derby to parse an SQL statement
by Rick Hillegas-2
::
Rate this Message:
Hi Flavio,
I have checked the patch into the trunk, so that eliminates one of the steps. At this point, this is what you need to do: 1) Build the development trunk. The instructions can be found on this web pages http://wiki.apache.org/db-derby/ForNewDevelopers and in particular, here: http://wiki.apache.org/db-derby/ForNewDevelopers#head-278c37b71407ea38bf6f3310a13d7ebce3e2a32c 2) Compile the ASTParser program 3) Run ASTParser, wiring into the classpath the Derby jars which you built in step (1). Please let us know how this works out for you. Thanks, -Rick Flavio Palumbo wrote: > Hi guys, > > I followed this post finding it very exciting, cause I post a similar > question a while ago. > > Now I'd like to test the work submitted by Rick but I'm not so inside Derby > to catch he whole job I have to do. > > I understood that I have to : > > - download Derby sources (from where ?) > - apply the patch suggested by Rich (seen the classes but not catch the > lines of code) > - recompile Derby (what libraries/jars I need to) > - use ASTParser as suggested > > Can somebody give me a hint ? > > Thanks a lot > > Flavio > > >> -----Messaggio originale----- >> Da: news [mailto:news@...]Per conto di Christian Riedel >> Inviato: giovedì 13 novembre 2008 6.37 >> A: derby-user@... >> Oggetto: Re: Using derby to parse an SQL statement >> >> >> Hi Rick, >> >> at first thank you very much for your efforts so far. At a first glance >> your changes to the code seem to be exactly what we want. I will try if >> it works asap. >> >> To test it with the derby libs I'd have to work on the current trunk and >> apply the patch an then compile derby manually, right? >> >> I'll keep you updated >> >> Thanks for your help >> >> Christian >> >> Rick Hillegas schrieb: >> >>> Hi Christian, >>> >>> I have created a JIRA to track this issue: >>> https://issues.apache.org/jira/browse/DERBY-3946 >>> >>> I have attached to the JIRA a small patch which exposes the AST >>> >> produced >> >>> by the parser. I have also attached a simple program, ASTParser, which >>> shows how to retrieve the AST from Derby. I am inclined to check this >>> patch in to the trunk. Please let me know if you find this >>> >> useful and if >> >>> you would like me to port this patch to another Derby branch. >>> >>> Hope this helps, >>> -Rick >>> >>> Christian Riedel wrote: >>> >>>> Hi Rick, >>>> >>>> first of all thanks for your answer ... now the relations have become >>>> a lot clearer ... >>>> >>>> Your are right, there is a lot of things to be done that we probably >>>> don't want to go through. You asked why we cannot take the whole derby >>>> engine and use it ... well there is nor real reason not to do so. The >>>> only "problem" I see is, that derby is a dbms - if I am not mistaken - >>>> and we only have an SQL statement that we extract from a text file and >>>> want tot analyze it to extract some metadata from it. >>>> >>>> So if we take the derby engine as it is, how can I prevent that we >>>> have to set up a "dummy" DB in order to be able to actually use thje >>>> parsing feature .... >>>> >>>> I hope you see my point. >>>> >>>> We could live with setting up a dummy DB ... and I do think that the >>>> derby AST offers all information we need. It's just that I don't see >>>> how we can set this thing up. So having a dummy DB is necessary to be >>>> able to intercept the parsing process to get hold of the AST? Can we >>>> actually access the AST if we choose to set up a dummy DB? I think >>>> that would be something we could live with ;-) >>>> >>>> >>>> Thanks for your support >>>> >>>> Christian >>>> >>>> >>>> Rick Hillegas schrieb: >>>> >>>>> Hi Christian, >>>>> >>>>> I think you will have difficulty isolating the Parser from the rest >>>>> of the SQL interpreter. In theory, you should be able to isolate the >>>>> compiler from the execution engine and the storage layer--but that is >>>>> an untested theory. >>>>> >>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>>> the Parser would just need to ask a NodeFactory for AST nodes and you >>>>> could supply your own NodeFactory. But I think that there is a fair >>>>> amount of coupling between the Parser and Derby's concrete >>>>> implementation of NodeFactory. I think that you could uncouple the >>>>> two, but you may not want to spend your time on that. >>>>> >>>>> So the Parser is going to force you to pull in the AST nodes. Once >>>>> you do that, you will end up with the whole compiler. In particular, >>>>> the AST nodes (and the Parser itself) expect that you will supply an >>>>> implementation of LanguageConnectionContext, the master state >>>>> variable for the whole SQL interpreter. Untangling that requirement >>>>> is another chunk of work you may not want to do. >>>>> >>>>> Then there is the Monitor. It has been a while since I was in that >>>>> code but I seem to recall that fairly early on the Monitor wants to >>>>> fault in a storage layer. In theory you ought to be able to supply >>>>> the Monitor a list of modules that doesn't include a storage layer. >>>>> But since no-one runs in this configuration, there are probably a lot >>>>> of undocumented surprises that you may not want to fix either. >>>>> >>>>> Can I ask you what breaks if you just pull in the whole Derby engine? >>>>> Are you concerned that you will fault in too much code that you >>>>> barely use? Are you concerned that you'll end up with a dummy >>>>> database that you don't need? Are Derby's AST nodes not a usable >>>>> representation of statement syntax? >>>>> >>>>> Thanks, >>>>> -Rick >>>>> >>>>> Christian Riedel wrote: >>>>> >>>>>> Hi there, >>>>>> >>>>>> we are working on a small project where we need to analyze an SQL >>>>>> statement that can be of any kind: very simple, with inner selects, >>>>>> complex join etc. >>>>>> >>>>>> We figured it inappropriate to start to write our own parser when >>>>>> there are other projects, like derby, out there that can do it much >>>>>> better than we would possibly do ... so this was our idea: >>>>>> >>>>>> Can we use derby to create an instance of Parser >>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>> statement be parsed by calling the parse() method on this instance? >>>>>> What we want to have is a syntax tree of the statement that allows >>>>>> us to see which tables and which fields are accessed / included in >>>>>> the statement (including any possibly done "renames" á la SELECT >>>>>> street AS "ADDRESS" FROM USER_DATA ). >>>>>> >>>>>> The problem is, that we are stuck ... we spent several days now to >>>>>> try to find the proper way to create an instance of the Parser. Is >>>>>> it possible at all without having to set up a running derby system? >>>>>> >>>>>> Is the Monitor class the right entry point? How can we create a >>>>>> CompilerContext so that a Parser instance can be created? >>>>>> >>>>>> >>>>>> This sure is off-topic but we don't see any way through all this. >>>>>> Can you help us? >>>>>> >>>>>> >>>>>> Thanks in advance >>>>>> >>>>>> Christian >>>>>> >>>>>> >>>>> >>> >> -- >> To reply to this posting directly use the following address and >> remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... >> >> > > > ----------------------------------------------------------- > Il presente messaggio non costituisce un impegno contrattuale tra SILMA S.r.l. ed il destinatario. > Le opinioni ivi espresse sono quelle dell'autore. > SILMA S.r.l. non assume alcuna responsabilita riguardo al contenuto del presente messaggio. > Il messaggio è destinato esclusivamente al destinatario. > Il contenuto e gli allegati sono da considerarsi di natura confidenziale > > Nel caso abbiate ricevuto il presente messaggio per errore siete pregati di comunicarlo > alla casella segreteria@.... > > |
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Re: Using derby to parse an SQL statement
by Christian Riedel
::
Rate this Message:
Hi Rick,
that sounds wonderfull! I haven't had the chance to try your changes today, though. I'll check it tomorrow right away. Of course, I will report any insights / problems in Jira. Thanks for your great support! Christian Rick Hillegas schrieb: > Hi Christian, > > I have checked the patch into the development trunk. At this point, you > will automatically get the fix if you build an up-to-date copy of the > trunk. Please let us know what your experience is. You will notice from > the discussion on the JIRA that some syntax may not work--this is > because the separation between the parsing and name-resolution phases is > not as clean as it should be. The JIRA would be a good place for you to > record your observations. > > Thanks, > -Rick > > Christian Riedel wrote: >> Hi Rick, >> >> at first thank you very much for your efforts so far. At a first >> glance your changes to the code seem to be exactly what we want. I >> will try if it works asap. >> >> To test it with the derby libs I'd have to work on the current trunk >> and apply the patch an then compile derby manually, right? >> >> I'll keep you updated >> >> Thanks for your help >> >> Christian >> >> Rick Hillegas schrieb: >>> Hi Christian, >>> >>> I have created a JIRA to track this issue: >>> https://issues.apache.org/jira/browse/DERBY-3946 >>> >>> I have attached to the JIRA a small patch which exposes the AST >>> produced by the parser. I have also attached a simple program, >>> ASTParser, which shows how to retrieve the AST from Derby. I am >>> inclined to check this patch in to the trunk. Please let me know if >>> you find this useful and if you would like me to port this patch to >>> another Derby branch. >>> >>> Hope this helps, >>> -Rick >>> >>> Christian Riedel wrote: >>>> Hi Rick, >>>> >>>> first of all thanks for your answer ... now the relations have >>>> become a lot clearer ... >>>> >>>> Your are right, there is a lot of things to be done that we probably >>>> don't want to go through. You asked why we cannot take the whole >>>> derby engine and use it ... well there is nor real reason not to do >>>> so. The only "problem" I see is, that derby is a dbms - if I am not >>>> mistaken - and we only have an SQL statement that we extract from a >>>> text file and want tot analyze it to extract some metadata from it. >>>> >>>> So if we take the derby engine as it is, how can I prevent that we >>>> have to set up a "dummy" DB in order to be able to actually use thje >>>> parsing feature .... >>>> >>>> I hope you see my point. >>>> >>>> We could live with setting up a dummy DB ... and I do think that the >>>> derby AST offers all information we need. It's just that I don't see >>>> how we can set this thing up. So having a dummy DB is necessary to >>>> be able to intercept the parsing process to get hold of the AST? Can >>>> we actually access the AST if we choose to set up a dummy DB? I >>>> think that would be something we could live with ;-) >>>> >>>> >>>> Thanks for your support >>>> >>>> Christian >>>> >>>> >>>> Rick Hillegas schrieb: >>>>> Hi Christian, >>>>> >>>>> I think you will have difficulty isolating the Parser from the rest >>>>> of the SQL interpreter. In theory, you should be able to isolate >>>>> the compiler from the execution engine and the storage layer--but >>>>> that is an untested theory. >>>>> >>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>>> the Parser would just need to ask a NodeFactory for AST nodes and >>>>> you could supply your own NodeFactory. But I think that there is a >>>>> fair amount of coupling between the Parser and Derby's concrete >>>>> implementation of NodeFactory. I think that you could uncouple the >>>>> two, but you may not want to spend your time on that. >>>>> >>>>> So the Parser is going to force you to pull in the AST nodes. Once >>>>> you do that, you will end up with the whole compiler. In >>>>> particular, the AST nodes (and the Parser itself) expect that you >>>>> will supply an implementation of LanguageConnectionContext, the >>>>> master state variable for the whole SQL interpreter. Untangling >>>>> that requirement is another chunk of work you may not want to do. >>>>> >>>>> Then there is the Monitor. It has been a while since I was in that >>>>> code but I seem to recall that fairly early on the Monitor wants to >>>>> fault in a storage layer. In theory you ought to be able to supply >>>>> the Monitor a list of modules that doesn't include a storage layer. >>>>> But since no-one runs in this configuration, there are probably a >>>>> lot of undocumented surprises that you may not want to fix either. >>>>> >>>>> Can I ask you what breaks if you just pull in the whole Derby >>>>> engine? Are you concerned that you will fault in too much code that >>>>> you barely use? Are you concerned that you'll end up with a dummy >>>>> database that you don't need? Are Derby's AST nodes not a usable >>>>> representation of statement syntax? >>>>> >>>>> Thanks, >>>>> -Rick >>>>> >>>>> Christian Riedel wrote: >>>>>> Hi there, >>>>>> >>>>>> we are working on a small project where we need to analyze an SQL >>>>>> statement that can be of any kind: very simple, with inner >>>>>> selects, complex join etc. >>>>>> >>>>>> We figured it inappropriate to start to write our own parser when >>>>>> there are other projects, like derby, out there that can do it >>>>>> much better than we would possibly do ... so this was our idea: >>>>>> >>>>>> Can we use derby to create an instance of Parser >>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>> statement be parsed by calling the parse() method on this >>>>>> instance? What we want to have is a syntax tree of the statement >>>>>> that allows us to see which tables and which fields are accessed / >>>>>> included in the statement (including any possibly done "renames" á >>>>>> la SELECT street AS "ADDRESS" FROM USER_DATA ). >>>>>> >>>>>> The problem is, that we are stuck ... we spent several days now to >>>>>> try to find the proper way to create an instance of the Parser. Is >>>>>> it possible at all without having to set up a running derby system? >>>>>> >>>>>> Is the Monitor class the right entry point? How can we create a >>>>>> CompilerContext so that a Parser instance can be created? >>>>>> >>>>>> >>>>>> This sure is off-topic but we don't see any way through all this. >>>>>> Can you help us? >>>>>> >>>>>> >>>>>> Thanks in advance >>>>>> >>>>>> Christian >>>>>> >>>>> >>>>> >>>> >>> >>> >> > > -- To reply to this posting directly use the following address and remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... |
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Re: Using derby to parse an SQL statement
by Christian Riedel
::
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Sorry, if this is a duplicate ... it seems my message was not delivered
in the first place. Hi Rick, that sounds wonderfull! I haven't had the chance to try your changes today, though. I'll check it tomorrow right away. Of course, I will report any insights / problems in Jira. Thanks for your great support! Christian Rick Hillegas schrieb: > Hi Christian, > > I have checked the patch into the development trunk. At this point, you > will automatically get the fix if you build an up-to-date copy of the > trunk. Please let us know what your experience is. You will notice from > the discussion on the JIRA that some syntax may not work--this is > because the separation between the parsing and name-resolution phases is > not as clean as it should be. The JIRA would be a good place for you to > record your observations. > > Thanks, > -Rick > > Christian Riedel wrote: >> Hi Rick, >> >> at first thank you very much for your efforts so far. At a first >> glance your changes to the code seem to be exactly what we want. I >> will try if it works asap. >> >> To test it with the derby libs I'd have to work on the current trunk >> and apply the patch an then compile derby manually, right? >> >> I'll keep you updated >> >> Thanks for your help >> >> Christian >> >> Rick Hillegas schrieb: >>> Hi Christian, >>> >>> I have created a JIRA to track this issue: >>> https://issues.apache.org/jira/browse/DERBY-3946 >>> >>> I have attached to the JIRA a small patch which exposes the AST >>> produced by the parser. I have also attached a simple program, >>> ASTParser, which shows how to retrieve the AST from Derby. I am >>> inclined to check this patch in to the trunk. Please let me know if >>> you find this useful and if you would like me to port this patch to >>> another Derby branch. >>> >>> Hope this helps, >>> -Rick >>> >>> Christian Riedel wrote: >>>> Hi Rick, >>>> >>>> first of all thanks for your answer ... now the relations have >>>> become a lot clearer ... >>>> >>>> Your are right, there is a lot of things to be done that we probably >>>> don't want to go through. You asked why we cannot take the whole >>>> derby engine and use it ... well there is nor real reason not to do >>>> so. The only "problem" I see is, that derby is a dbms - if I am not >>>> mistaken - and we only have an SQL statement that we extract from a >>>> text file and want tot analyze it to extract some metadata from it. >>>> >>>> So if we take the derby engine as it is, how can I prevent that we >>>> have to set up a "dummy" DB in order to be able to actually use thje >>>> parsing feature .... >>>> >>>> I hope you see my point. >>>> >>>> We could live with setting up a dummy DB ... and I do think that the >>>> derby AST offers all information we need. It's just that I don't see >>>> how we can set this thing up. So having a dummy DB is necessary to >>>> be able to intercept the parsing process to get hold of the AST? Can >>>> we actually access the AST if we choose to set up a dummy DB? I >>>> think that would be something we could live with ;-) >>>> >>>> >>>> Thanks for your support >>>> >>>> Christian >>>> >>>> >>>> Rick Hillegas schrieb: >>>>> Hi Christian, >>>>> >>>>> I think you will have difficulty isolating the Parser from the rest >>>>> of the SQL interpreter. In theory, you should be able to isolate >>>>> the compiler from the execution engine and the storage layer--but >>>>> that is an untested theory. >>>>> >>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>>> the Parser would just need to ask a NodeFactory for AST nodes and >>>>> you could supply your own NodeFactory. But I think that there is a >>>>> fair amount of coupling between the Parser and Derby's concrete >>>>> implementation of NodeFactory. I think that you could uncouple the >>>>> two, but you may not want to spend your time on that. >>>>> >>>>> So the Parser is going to force you to pull in the AST nodes. Once >>>>> you do that, you will end up with the whole compiler. In >>>>> particular, the AST nodes (and the Parser itself) expect that you >>>>> will supply an implementation of LanguageConnectionContext, the >>>>> master state variable for the whole SQL interpreter. Untangling >>>>> that requirement is another chunk of work you may not want to do. >>>>> >>>>> Then there is the Monitor. It has been a while since I was in that >>>>> code but I seem to recall that fairly early on the Monitor wants to >>>>> fault in a storage layer. In theory you ought to be able to supply >>>>> the Monitor a list of modules that doesn't include a storage layer. >>>>> But since no-one runs in this configuration, there are probably a >>>>> lot of undocumented surprises that you may not want to fix either. >>>>> >>>>> Can I ask you what breaks if you just pull in the whole Derby >>>>> engine? Are you concerned that you will fault in too much code that >>>>> you barely use? Are you concerned that you'll end up with a dummy >>>>> database that you don't need? Are Derby's AST nodes not a usable >>>>> representation of statement syntax? >>>>> >>>>> Thanks, >>>>> -Rick >>>>> >>>>> Christian Riedel wrote: >>>>>> Hi there, >>>>>> >>>>>> we are working on a small project where we need to analyze an SQL >>>>>> statement that can be of any kind: very simple, with inner >>>>>> selects, complex join etc. >>>>>> >>>>>> We figured it inappropriate to start to write our own parser when >>>>>> there are other projects, like derby, out there that can do it >>>>>> much better than we would possibly do ... so this was our idea: >>>>>> >>>>>> Can we use derby to create an instance of Parser >>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>> statement be parsed by calling the parse() method on this >>>>>> instance? What we want to have is a syntax tree of the statement >>>>>> that allows us to see which tables and which fields are accessed / >>>>>> included in the statement (including any possibly done "renames" á >>>>>> la SELECT street AS "ADDRESS" FROM USER_DATA ). >>>>>> >>>>>> The problem is, that we are stuck ... we spent several days now to >>>>>> try to find the proper way to create an instance of the Parser. Is >>>>>> it possible at all without having to set up a running derby system? >>>>>> >>>>>> Is the Monitor class the right entry point? How can we create a >>>>>> CompilerContext so that a Parser instance can be created? >>>>>> >>>>>> >>>>>> This sure is off-topic but we don't see any way through all this. >>>>>> Can you help us? >>>>>> >>>>>> >>>>>> Thanks in advance >>>>>> >>>>>> Christian >>>>>> >>>>> >>>>> >>>> >>> >>> >> > > -- To reply to this posting directly use the following address and remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... |
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R: R: Using derby to parse an SQL statement
by Flavio Palumbo
::
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Hi Rick,
after some trouble compiling Derby, I was able to run ASTParser. At a first glance it seems exactly what I need. Now I'd like to test ASTParser with some different use cases. Could you please help me to figure out the whole content of the output of ASTParser ? Thanks a lot. Flavio > -----Messaggio originale----- > Da: Richard.Hillegas@... [mailto:Richard.Hillegas@...] > Inviato: giovedì 13 novembre 2008 14.56 > A: Derby Discussion > Oggetto: Re: R: Using derby to parse an SQL statement > > > Hi Flavio, > > I have checked the patch into the trunk, so that eliminates one of the > steps. At this point, this is what you need to do: > > 1) Build the development trunk. The instructions can be found on this > web pages > > http://wiki.apache.org/db-derby/ForNewDevelopers > > and in particular, here: > > > http://wiki.apache.org/db-derby/ForNewDevelopers#head-278c37b71407 > > 2) Compile the ASTParser program > > 3) Run ASTParser, wiring into the classpath the Derby jars which you > built in step (1). > > Please let us know how this works out for you. > > Thanks, > -Rick > > > Flavio Palumbo wrote: > > Hi guys, > > > > I followed this post finding it very exciting, cause I post a similar > > question a while ago. > > > > Now I'd like to test the work submitted by Rick but I'm not so > inside Derby > > to catch he whole job I have to do. > > > > I understood that I have to : > > > > - download Derby sources (from where ?) > > - apply the patch suggested by Rich (seen the classes but not catch the > > lines of code) > > - recompile Derby (what libraries/jars I need to) > > - use ASTParser as suggested > > > > Can somebody give me a hint ? > > > > Thanks a lot > > > > Flavio > > > > > >> -----Messaggio originale----- > >> Da: news [mailto:news@...]Per conto di Christian Riedel > >> Inviato: giovedì 13 novembre 2008 6.37 > >> A: derby-user@... > >> Oggetto: Re: Using derby to parse an SQL statement > >> > >> > >> Hi Rick, > >> > >> at first thank you very much for your efforts so far. At a first glance > >> your changes to the code seem to be exactly what we want. I will try if > >> it works asap. > >> > >> To test it with the derby libs I'd have to work on the current > trunk and > >> apply the patch an then compile derby manually, right? > >> > >> I'll keep you updated > >> > >> Thanks for your help > >> > >> Christian > >> > >> Rick Hillegas schrieb: > >> > >>> Hi Christian, > >>> > >>> I have created a JIRA to track this issue: > >>> https://issues.apache.org/jira/browse/DERBY-3946 > >>> > >>> I have attached to the JIRA a small patch which exposes the AST > >>> > >> produced > >> > >>> by the parser. I have also attached a simple program, ASTParser, which > >>> shows how to retrieve the AST from Derby. I am inclined to check this > >>> patch in to the trunk. Please let me know if you find this > >>> > >> useful and if > >> > >>> you would like me to port this patch to another Derby branch. > >>> > >>> Hope this helps, > >>> -Rick > >>> > >>> Christian Riedel wrote: > >>> > >>>> Hi Rick, > >>>> > >>>> first of all thanks for your answer ... now the relations have become > >>>> a lot clearer ... > >>>> > >>>> Your are right, there is a lot of things to be done that we probably > >>>> don't want to go through. You asked why we cannot take the > whole derby > >>>> engine and use it ... well there is nor real reason not to do so. The > >>>> only "problem" I see is, that derby is a dbms - if I am not > mistaken - > >>>> and we only have an SQL statement that we extract from a > text file and > >>>> want tot analyze it to extract some metadata from it. > >>>> > >>>> So if we take the derby engine as it is, how can I prevent that we > >>>> have to set up a "dummy" DB in order to be able to actually use thje > >>>> parsing feature .... > >>>> > >>>> I hope you see my point. > >>>> > >>>> We could live with setting up a dummy DB ... and I do think that the > >>>> derby AST offers all information we need. It's just that I don't see > >>>> how we can set this thing up. So having a dummy DB is necessary to be > >>>> able to intercept the parsing process to get hold of the AST? Can we > >>>> actually access the AST if we choose to set up a dummy DB? I think > >>>> that would be something we could live with ;-) > >>>> > >>>> > >>>> Thanks for your support > >>>> > >>>> Christian > >>>> > >>>> > >>>> Rick Hillegas schrieb: > >>>> > >>>>> Hi Christian, > >>>>> > >>>>> I think you will have difficulty isolating the Parser from the rest > >>>>> of the SQL interpreter. In theory, you should be able to isolate the > >>>>> compiler from the execution engine and the storage > layer--but that is > >>>>> an untested theory. > >>>>> > >>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, > >>>>> the Parser would just need to ask a NodeFactory for AST > nodes and you > >>>>> could supply your own NodeFactory. But I think that there is a fair > >>>>> amount of coupling between the Parser and Derby's concrete > >>>>> implementation of NodeFactory. I think that you could uncouple the > >>>>> two, but you may not want to spend your time on that. > >>>>> > >>>>> So the Parser is going to force you to pull in the AST nodes. Once > >>>>> you do that, you will end up with the whole compiler. In particular, > >>>>> the AST nodes (and the Parser itself) expect that you will supply an > >>>>> implementation of LanguageConnectionContext, the master state > >>>>> variable for the whole SQL interpreter. Untangling that requirement > >>>>> is another chunk of work you may not want to do. > >>>>> > >>>>> Then there is the Monitor. It has been a while since I was in that > >>>>> code but I seem to recall that fairly early on the Monitor wants to > >>>>> fault in a storage layer. In theory you ought to be able to supply > >>>>> the Monitor a list of modules that doesn't include a storage layer. > >>>>> But since no-one runs in this configuration, there are > probably a lot > >>>>> of undocumented surprises that you may not want to fix either. > >>>>> > >>>>> Can I ask you what breaks if you just pull in the whole > Derby engine? > >>>>> Are you concerned that you will fault in too much code that you > >>>>> barely use? Are you concerned that you'll end up with a dummy > >>>>> database that you don't need? Are Derby's AST nodes not a usable > >>>>> representation of statement syntax? > >>>>> > >>>>> Thanks, > >>>>> -Rick > >>>>> > >>>>> Christian Riedel wrote: > >>>>> > >>>>>> Hi there, > >>>>>> > >>>>>> we are working on a small project where we need to analyze an SQL > >>>>>> statement that can be of any kind: very simple, with inner selects, > >>>>>> complex join etc. > >>>>>> > >>>>>> We figured it inappropriate to start to write our own parser when > >>>>>> there are other projects, like derby, out there that can do it much > >>>>>> better than we would possibly do ... so this was our idea: > >>>>>> > >>>>>> Can we use derby to create an instance of Parser > >>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL > >>>>>> statement be parsed by calling the parse() method on this instance? > >>>>>> What we want to have is a syntax tree of the statement that allows > >>>>>> us to see which tables and which fields are accessed / included in > >>>>>> the statement (including any possibly done "renames" á la SELECT > >>>>>> street AS "ADDRESS" FROM USER_DATA ). > >>>>>> > >>>>>> The problem is, that we are stuck ... we spent several days now to > >>>>>> try to find the proper way to create an instance of the Parser. Is > >>>>>> it possible at all without having to set up a running derby system? > >>>>>> > >>>>>> Is the Monitor class the right entry point? How can we create a > >>>>>> CompilerContext so that a Parser instance can be created? > >>>>>> > >>>>>> > >>>>>> This sure is off-topic but we don't see any way through all this. > >>>>>> Can you help us? > >>>>>> > >>>>>> > >>>>>> Thanks in advance > >>>>>> > >>>>>> Christian > >>>>>> > >>>>>> > >>>>> > >>> > >> -- > >> To reply to this posting directly use the following address and > >> remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... > >> > >> > > > > > > ----------------------------------------------------------- > > Il presente messaggio non costituisce un impegno contrattuale > tra SILMA S.r.l. ed il destinatario. > > Le opinioni ivi espresse sono quelle dell'autore. > > SILMA S.r.l. non assume alcuna responsabilita riguardo al > contenuto del presente messaggio. > > Il messaggio è destinato esclusivamente al destinatario. > > Il contenuto e gli allegati sono da considerarsi di natura confidenziale > > > > Nel caso abbiate ricevuto il presente messaggio per errore > siete pregati di comunicarlo > > alla casella segreteria@.... > > > > > ----------------------------------------------------------- Il presente messaggio non costituisce un impegno contrattuale tra SILMA S.r.l. ed il destinatario. Le opinioni ivi espresse sono quelle dell'autore. SILMA S.r.l. non assume alcuna responsabilita riguardo al contenuto del presente messaggio. Il messaggio è destinato esclusivamente al destinatario. Il contenuto e gli allegati sono da considerarsi di natura confidenziale Nel caso abbiate ricevuto il presente messaggio per errore siete pregati di comunicarlo alla casella segreteria@.... |
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Re: R: Using derby to parse an SQL statement
by Rick Hillegas-2
::
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Hi Flavio,
I don't think that we have a good primer on the AST nodes. However, you can get some sense of what the nodes mean by building the Derby javadoc and looking at the javadoc for the package org.apache.derby.impl.sql.compile. Now that you've gotten over the hard hurdle of building the Derby classes, building the javadoc is easy: ant -quiet javadoc This will build the javadoc into the directory javadoc/engine. Once you have built the engine javadoc, browse to the org.apache.derby.impl.sql.compile package. The header comments on the classes are usually pretty helpful. I also recommend taking a look at the tree view of that package. You will see that the AST nodes are all of the classes indented under QueryTreeNode. Understanding the AST graph takes some patience. There are two useful techniques for figuring out how the nodes snap together into a graph: 1) The nodes themselves implement org.apache.derby.iapi.sql.compile.Visitable. That interface has one method, accept(). Not all AST nodes directly implement accept() so you may have to inspect their superclasses. The accept() method shows you what each node thinks its subnodes are. You can write your own tool to explore the graph by coding your implementation of the graph walker, org.apache.derby.iapi.sql.compile.Visitor. 2) The nodes also implement a pretty-printing method, treePrint(). The treePrint() method is another example of what a node thinks its subnodes are. This is the method which ASTParser calls on the top node. That should get you started. The devil is in the details, but keep posting questions and I think you'll get to the bottom of it. Hope this helps, -Rick Flavio Palumbo wrote: > Hi guys, > > I followed this post finding it very exciting, cause I post a similar > question a while ago. > > Now I'd like to test the work submitted by Rick but I'm not so inside Derby > to catch he whole job I have to do. > > I understood that I have to : > > - download Derby sources (from where ?) > - apply the patch suggested by Rich (seen the classes but not catch the > lines of code) > - recompile Derby (what libraries/jars I need to) > - use ASTParser as suggested > > Can somebody give me a hint > > Thanks a lot > > Flavio > > >> -----Messaggio originale----- >> Da: news [mailto:news@...]Per conto di Christian Riedel >> Inviato: giovedì 13 novembre 2008 6.37 >> A: derby-user@... >> Oggetto: Re: Using derby to parse an SQL statement >> >> >> Hi Rick, >> >> at first thank you very much for your efforts so far. At a first glance >> your changes to the code seem to be exactly what we want. I will try if >> it works asap. >> >> To test it with the derby libs I'd have to work on the current trunk and >> apply the patch an then compile derby manually, right? >> >> I'll keep you updated >> >> Thanks for your help >> >> Christian >> >> Rick Hillegas schrieb: >> >>> Hi Christian, >>> >>> I have created a JIRA to track this issue: >>> https://issues.apache.org/jira/browse/DERBY-3946 >>> >>> I have attached to the JIRA a small patch which exposes the AST >>> >> produced >> >>> by the parser. I have also attached a simple program, ASTParser, which >>> shows how to retrieve the AST from Derby. I am inclined to check this >>> patch in to the trunk. Please let me know if you find this >>> >> useful and if >> >>> you would like me to port this patch to another Derby branch. >>> >>> Hope this helps, >>> -Rick >>> >>> Christian Riedel wrote: >>> >>>> Hi Rick, >>>> >>>> first of all thanks for your answer ... now the relations have become >>>> a lot clearer ... >>>> >>>> Your are right, there is a lot of things to be done that we probably >>>> don't want to go through. You asked why we cannot take the whole derby >>>> engine and use it ... well there is nor real reason not to do so. The >>>> only "problem" I see is, that derby is a dbms - if I am not mistaken - >>>> and we only have an SQL statement that we extract from a text file and >>>> want tot analyze it to extract some metadata from it. >>>> >>>> So if we take the derby engine as it is, how can I prevent that we >>>> have to set up a "dummy" DB in order to be able to actually use thje >>>> parsing feature .... >>>> >>>> I hope you see my point. >>>> >>>> We could live with setting up a dummy DB ... and I do think that the >>>> derby AST offers all information we need. It's just that I don't see >>>> how we can set this thing up. So having a dummy DB is necessary to be >>>> able to intercept the parsing process to get hold of the AST? Can we >>>> actually access the AST if we choose to set up a dummy DB? I think >>>> that would be something we could live with ;-) >>>> >>>> >>>> Thanks for your support >>>> >>>> Christian >>>> >>>> >>>> Rick Hillegas schrieb: >>>> >>>>> Hi Christian, >>>>> >>>>> I think you will have difficulty isolating the Parser from the rest >>>>> of the SQL interpreter. In theory, you should be able to isolate the >>>>> compiler from the execution engine and the storage layer--but that is >>>>> an untested theory. >>>>> >>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>>> the Parser would just need to ask a NodeFactory for AST nodes and you >>>>> could supply your own NodeFactory. But I think that there is a fair >>>>> amount of coupling between the Parser and Derby's concrete >>>>> implementation of NodeFactory. I think that you could uncouple the >>>>> two, but you may not want to spend your time on that. >>>>> >>>>> So the Parser is going to force you to pull in the AST nodes. Once >>>>> you do that, you will end up with the whole compiler. In particular, >>>>> the AST nodes (and the Parser itself) expect that you will supply an >>>>> implementation of LanguageConnectionContext, the master state >>>>> variable for the whole SQL interpreter. Untangling that requirement >>>>> is another chunk of work you may not want to do. >>>>> >>>>> Then there is the Monitor. It has been a while since I was in that >>>>> code but I seem to recall that fairly early on the Monitor wants to >>>>> fault in a storage layer. In theory you ought to be able to supply >>>>> the Monitor a list of modules that doesn't include a storage layer. >>>>> But since no-one runs in this configuration, there are probably a lot >>>>> of undocumented surprises that you may not want to fix either. >>>>> >>>>> Can I ask you what breaks if you just pull in the whole Derby engine? >>>>> Are you concerned that you will fault in too much code that you >>>>> barely use? Are you concerned that you'll end up with a dummy >>>>> database that you don't need? Are Derby's AST nodes not a usable >>>>> representation of statement syntax? >>>>> >>>>> Thanks, >>>>> -Rick >>>>> >>>>> Christian Riedel wrote: >>>>> >>>>>> Hi there, >>>>>> >>>>>> we are working on a small project where we need to analyze an SQL >>>>>> statement that can be of any kind: very simple, with inner selects, >>>>>> complex join etc. >>>>>> >>>>>> We figured it inappropriate to start to write our own parser when >>>>>> there are other projects, like derby, out there that can do it much >>>>>> better than we would possibly do ... so this was our idea: >>>>>> >>>>>> Can we use derby to create an instance of Parser >>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>> statement be parsed by calling the parse() method on this instance? >>>>>> What we want to have is a syntax tree of the statement that allows >>>>>> us to see which tables and which fields are accessed / included in >>>>>> the statement (including any possibly done "renames" á la SELECT >>>>>> street AS "ADDRESS" FROM USER_DATA ). >>>>>> >>>>>> The problem is, that we are stuck ... we spent several days now to >>>>>> try to find the proper way to create an instance of the Parser. Is >>>>>> it possible at all without having to set up a running derby system? >>>>>> >>>>>> Is the Monitor class the right entry point? How can we create a >>>>>> CompilerContext so that a Parser instance can be created? >>>>>> >>>>>> >>>>>> This sure is off-topic but we don't see any way through all this. >>>>>> Can you help us? >>>>>> >>>>>> >>>>>> Thanks in advance >>>>>> >>>>>> Christian >>>>>> >>>>>> >>>>> >>> >> -- >> To reply to this posting directly use the following address and >> remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... >> >> > > > ----------------------------------------------------------- > Il presente messaggio non costituisce un impegno contrattuale tra SILMA S.r.l. ed il destinatario. > Le opinioni ivi espresse sono quelle dell'autore. > SILMA S.r.l. non assume alcuna responsabilita riguardo al contenuto del presente messaggio. > Il messaggio è destinato esclusivamente al destinatario. > Il contenuto e gli allegati sono da considerarsi di natura confidenziale > > Nel caso abbiate ricevuto il presente messaggio per errore siete pregati di comunicarlo > alla casella segreteria@.... > > |
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Re: R: Using derby to parse an SQL statement
by Rick Hillegas-2
::
Rate this Message:
Hi Flavio,
I have attached a TreeWalker class to https://issues.apache.org/jira/browse/DERBY-3946 This may help you explore the AST. Hope this helps, -Rick Rick Hillegas wrote: > Hi Flavio, > > I don't think that we have a good primer on the AST nodes. However, > you can get some sense of what the nodes mean by building the Derby > javadoc and looking at the javadoc for the package > org.apache.derby.impl.sql.compile. > > Now that you've gotten over the hard hurdle of building the Derby > classes, building the javadoc is easy: > > ant -quiet javadoc > > This will build the javadoc into the directory javadoc/engine. Once > you have built the engine javadoc, browse to the > org.apache.derby.impl.sql.compile package. The header comments on the > classes are usually pretty helpful. I also recommend taking a look at > the tree view of that package. You will see that the AST nodes are all > of the classes indented under QueryTreeNode. > > Understanding the AST graph takes some patience. There are two useful > techniques for figuring out how the nodes snap together into a graph: > > 1) The nodes themselves implement > org.apache.derby.iapi.sql.compile.Visitable. That interface has one > method, accept(). Not all AST nodes directly implement accept() so you > may have to inspect their superclasses. The accept() method shows you > what each node thinks its subnodes are. You can write your own tool to > explore the graph by coding your implementation of the graph walker, > org.apache.derby.iapi.sql.compile.Visitor. > > 2) The nodes also implement a pretty-printing method, treePrint(). The > treePrint() method is another example of what a node thinks its > subnodes are. This is the method which ASTParser calls on the top node. > > That should get you started. The devil is in the details, but keep > posting questions and I think you'll get to the bottom of it. > > Hope this helps, > -Rick > > Flavio Palumbo wrote: >> Hi guys, >> >> I followed this post finding it very exciting, cause I post a similar >> question a while ago. >> >> Now I'd like to test the work submitted by Rick but I'm not so inside >> Derby >> to catch he whole job I have to do. >> >> I understood that I have to : >> >> - download Derby sources (from where ?) >> - apply the patch suggested by Rich (seen the classes but not catch the >> lines of code) >> - recompile Derby (what libraries/jars I need to) >> - use ASTParser as suggested >> >> Can somebody give me a hint Thanks a lot >> >> Flavio >> >> >>> -----Messaggio originale----- >>> Da: news [mailto:news@...]Per conto di Christian Riedel >>> Inviato: giovedì 13 novembre 2008 6.37 >>> A: derby-user@... >>> Oggetto: Re: Using derby to parse an SQL statement >>> >>> >>> Hi Rick, >>> >>> at first thank you very much for your efforts so far. At a first glance >>> your changes to the code seem to be exactly what we want. I will try if >>> it works asap. >>> >>> To test it with the derby libs I'd have to work on the current trunk >>> and >>> apply the patch an then compile derby manually, right? >>> >>> I'll keep you updated >>> >>> Thanks for your help >>> >>> Christian >>> >>> Rick Hillegas schrieb: >>> >>>> Hi Christian, >>>> >>>> I have created a JIRA to track this issue: >>>> https://issues.apache.org/jira/browse/DERBY-3946 >>>> >>>> I have attached to the JIRA a small patch which exposes the AST >>>> >>> produced >>> >>>> by the parser. I have also attached a simple program, ASTParser, which >>>> shows how to retrieve the AST from Derby. I am inclined to check this >>>> patch in to the trunk. Please let me know if you find this >>>> >>> useful and if >>> >>>> you would like me to port this patch to another Derby branch. >>>> >>>> Hope this helps, >>>> -Rick >>>> >>>> Christian Riedel wrote: >>>> >>>>> Hi Rick, >>>>> >>>>> first of all thanks for your answer ... now the relations have become >>>>> a lot clearer ... >>>>> >>>>> Your are right, there is a lot of things to be done that we probably >>>>> don't want to go through. You asked why we cannot take the whole >>>>> derby >>>>> engine and use it ... well there is nor real reason not to do so. The >>>>> only "problem" I see is, that derby is a dbms - if I am not >>>>> mistaken - >>>>> and we only have an SQL statement that we extract from a text file >>>>> and >>>>> want tot analyze it to extract some metadata from it. >>>>> >>>>> So if we take the derby engine as it is, how can I prevent that we >>>>> have to set up a "dummy" DB in order to be able to actually use thje >>>>> parsing feature .... >>>>> >>>>> I hope you see my point. >>>>> >>>>> We could live with setting up a dummy DB ... and I do think that the >>>>> derby AST offers all information we need. It's just that I don't see >>>>> how we can set this thing up. So having a dummy DB is necessary to be >>>>> able to intercept the parsing process to get hold of the AST? Can we >>>>> actually access the AST if we choose to set up a dummy DB? I think >>>>> that would be something we could live with ;-) >>>>> >>>>> >>>>> Thanks for your support >>>>> >>>>> Christian >>>>> >>>>> >>>>> Rick Hillegas schrieb: >>>>> >>>>>> Hi Christian, >>>>>> >>>>>> I think you will have difficulty isolating the Parser from the rest >>>>>> of the SQL interpreter. In theory, you should be able to isolate the >>>>>> compiler from the execution engine and the storage layer--but >>>>>> that is >>>>>> an untested theory. >>>>>> >>>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>>>> the Parser would just need to ask a NodeFactory for AST nodes and >>>>>> you >>>>>> could supply your own NodeFactory. But I think that there is a fair >>>>>> amount of coupling between the Parser and Derby's concrete >>>>>> implementation of NodeFactory. I think that you could uncouple the >>>>>> two, but you may not want to spend your time on that. >>>>>> >>>>>> So the Parser is going to force you to pull in the AST nodes. Once >>>>>> you do that, you will end up with the whole compiler. In particular, >>>>>> the AST nodes (and the Parser itself) expect that you will supply an >>>>>> implementation of LanguageConnectionContext, the master state >>>>>> variable for the whole SQL interpreter. Untangling that requirement >>>>>> is another chunk of work you may not want to do. >>>>>> >>>>>> Then there is the Monitor. It has been a while since I was in that >>>>>> code but I seem to recall that fairly early on the Monitor wants to >>>>>> fault in a storage layer. In theory you ought to be able to supply >>>>>> the Monitor a list of modules that doesn't include a storage layer. >>>>>> But since no-one runs in this configuration, there are probably a >>>>>> lot >>>>>> of undocumented surprises that you may not want to fix either. >>>>>> >>>>>> Can I ask you what breaks if you just pull in the whole Derby >>>>>> engine? >>>>>> Are you concerned that you will fault in too much code that you >>>>>> barely use? Are you concerned that you'll end up with a dummy >>>>>> database that you don't need? Are Derby's AST nodes not a usable >>>>>> representation of statement syntax? >>>>>> >>>>>> Thanks, >>>>>> -Rick >>>>>> >>>>>> Christian Riedel wrote: >>>>>> >>>>>>> Hi there, >>>>>>> >>>>>>> we are working on a small project where we need to analyze an SQL >>>>>>> statement that can be of any kind: very simple, with inner selects, >>>>>>> complex join etc. >>>>>>> >>>>>>> We figured it inappropriate to start to write our own parser when >>>>>>> there are other projects, like derby, out there that can do it much >>>>>>> better than we would possibly do ... so this was our idea: >>>>>>> >>>>>>> Can we use derby to create an instance of Parser >>>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>>> statement be parsed by calling the parse() method on this instance? >>>>>>> What we want to have is a syntax tree of the statement that allows >>>>>>> us to see which tables and which fields are accessed / included in >>>>>>> the statement (including any possibly done "renames" á la SELECT >>>>>>> street AS "ADDRESS" FROM USER_DATA ). >>>>>>> >>>>>>> The problem is, that we are stuck ... we spent several days now to >>>>>>> try to find the proper way to create an instance of the Parser. Is >>>>>>> it possible at all without having to set up a running derby system? >>>>>>> >>>>>>> Is the Monitor class the right entry point? How can we create a >>>>>>> CompilerContext so that a Parser instance can be created? >>>>>>> >>>>>>> >>>>>>> This sure is off-topic but we don't see any way through all this. >>>>>>> Can you help us? >>>>>>> >>>>>>> >>>>>>> Thanks in advance >>>>>>> >>>>>>> Christian >>>>>>> >>>>>>> >>>>>> >>>> >>> -- >>> To reply to this posting directly use the following address and >>> remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... >>> >>> >> >> >> ----------------------------------------------------------- >> Il presente messaggio non costituisce un impegno contrattuale tra >> SILMA S.r.l. ed il destinatario. >> Le opinioni ivi espresse sono quelle dell'autore. >> SILMA S.r.l. non assume alcuna responsabilita riguardo al contenuto >> del presente messaggio. >> Il messaggio è destinato esclusivamente al destinatario. >> Il contenuto e gli allegati sono da considerarsi di natura confidenziale >> >> Nel caso abbiate ricevuto il presente messaggio per errore siete >> pregati di comunicarlo >> alla casella segreteria@.... >> >> > |
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Re: R: Using derby to parse an SQL statement
by Andrew McIntyre-2
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Rate this Message:
On Fri, Nov 14, 2008 at 6:15 AM, Rick Hillegas <Richard.Hillegas@...> wrote:
> Hi Flavio, > > I don't think that we have a good primer on the AST nodes. However, you can > get some sense of what the nodes mean by building the Derby javadoc and > looking at the javadoc for the package org.apache.derby.impl.sql.compile. The engine javadoc is also available online: http://db.apache.org/derby/javadoc/engine/ cheers, andrew |
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Re: Using derby to parse an SQL statement
by Christian Riedel
::
Rate this Message:
Hi Rick,
as requested I want to report our findings when working with the parser: Background: we want to use the parser to analyze SQL statements that are generated by different tools, for example an ETL tool. It seems that, depending on the DBMS the tools are configured to work with, the generated SQL is not completely standard conform, which causes a parser exception. As example the statement select null "a_null_column", id "an_id_column" from a_table runs fine on an MSSQL DB, but causes problems on a DB2. Feeding the parser with this statement brings up a parsing exception. Supposedly because it is not SQL standard conform. Our question is: Does the derby parser "only" understand standard SQL or can it be instructed to accept DB2, Oracle, MSSQL etc. specific syntax as well? Other than this we have not had any problems with the parser. Using the Derby AST brings the information we wanted. I hope you can help us with this problem as well. Regards Christian Rick Hillegas schrieb: > Hi Christian, > > I have checked the patch into the development trunk. At this point, you > will automatically get the fix if you build an up-to-date copy of the > trunk. Please let us know what your experience is. You will notice from > the discussion on the JIRA that some syntax may not work--this is > because the separation between the parsing and name-resolution phases is > not as clean as it should be. The JIRA would be a good place for you to > record your observations. > > Thanks, > -Rick > > Christian Riedel wrote: >> Hi Rick, >> >> at first thank you very much for your efforts so far. At a first >> glance your changes to the code seem to be exactly what we want. I >> will try if it works asap. >> >> To test it with the derby libs I'd have to work on the current trunk >> and apply the patch an then compile derby manually, right? >> >> I'll keep you updated >> >> Thanks for your help >> >> Christian >> >> Rick Hillegas schrieb: >>> Hi Christian, >>> >>> I have created a JIRA to track this issue: >>> https://issues.apache.org/jira/browse/DERBY-3946 >>> >>> I have attached to the JIRA a small patch which exposes the AST >>> produced by the parser. I have also attached a simple program, >>> ASTParser, which shows how to retrieve the AST from Derby. I am >>> inclined to check this patch in to the trunk. Please let me know if >>> you find this useful and if you would like me to port this patch to >>> another Derby branch. >>> >>> Hope this helps, >>> -Rick >>> >>> Christian Riedel wrote: >>>> Hi Rick, >>>> >>>> first of all thanks for your answer ... now the relations have >>>> become a lot clearer ... >>>> >>>> Your are right, there is a lot of things to be done that we probably >>>> don't want to go through. You asked why we cannot take the whole >>>> derby engine and use it ... well there is nor real reason not to do >>>> so. The only "problem" I see is, that derby is a dbms - if I am not >>>> mistaken - and we only have an SQL statement that we extract from a >>>> text file and want tot analyze it to extract some metadata from it. >>>> >>>> So if we take the derby engine as it is, how can I prevent that we >>>> have to set up a "dummy" DB in order to be able to actually use thje >>>> parsing feature .... >>>> >>>> I hope you see my point. >>>> >>>> We could live with setting up a dummy DB ... and I do think that the >>>> derby AST offers all information we need. It's just that I don't see >>>> how we can set this thing up. So having a dummy DB is necessary to >>>> be able to intercept the parsing process to get hold of the AST? Can >>>> we actually access the AST if we choose to set up a dummy DB? I >>>> think that would be something we could live with ;-) >>>> >>>> >>>> Thanks for your support >>>> >>>> Christian >>>> >>>> >>>> Rick Hillegas schrieb: >>>>> Hi Christian, >>>>> >>>>> I think you will have difficulty isolating the Parser from the rest >>>>> of the SQL interpreter. In theory, you should be able to isolate >>>>> the compiler from the execution engine and the storage layer--but >>>>> that is an untested theory. >>>>> >>>>> The Parser wants to turn out abstract syntax trees (AST). Ideally, >>>>> the Parser would just need to ask a NodeFactory for AST nodes and >>>>> you could supply your own NodeFactory. But I think that there is a >>>>> fair amount of coupling between the Parser and Derby's concrete >>>>> implementation of NodeFactory. I think that you could uncouple the >>>>> two, but you may not want to spend your time on that. >>>>> >>>>> So the Parser is going to force you to pull in the AST nodes. Once >>>>> you do that, you will end up with the whole compiler. In >>>>> particular, the AST nodes (and the Parser itself) expect that you >>>>> will supply an implementation of LanguageConnectionContext, the >>>>> master state variable for the whole SQL interpreter. Untangling >>>>> that requirement is another chunk of work you may not want to do. >>>>> >>>>> Then there is the Monitor. It has been a while since I was in that >>>>> code but I seem to recall that fairly early on the Monitor wants to >>>>> fault in a storage layer. In theory you ought to be able to supply >>>>> the Monitor a list of modules that doesn't include a storage layer. >>>>> But since no-one runs in this configuration, there are probably a >>>>> lot of undocumented surprises that you may not want to fix either. >>>>> >>>>> Can I ask you what breaks if you just pull in the whole Derby >>>>> engine? Are you concerned that you will fault in too much code that >>>>> you barely use? Are you concerned that you'll end up with a dummy >>>>> database that you don't need? Are Derby's AST nodes not a usable >>>>> representation of statement syntax? >>>>> >>>>> Thanks, >>>>> -Rick >>>>> >>>>> Christian Riedel wrote: >>>>>> Hi there, >>>>>> >>>>>> we are working on a small project where we need to analyze an SQL >>>>>> statement that can be of any kind: very simple, with inner >>>>>> selects, complex join etc. >>>>>> >>>>>> We figured it inappropriate to start to write our own parser when >>>>>> there are other projects, like derby, out there that can do it >>>>>> much better than we would possibly do ... so this was our idea: >>>>>> >>>>>> Can we use derby to create an instance of Parser >>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>> statement be parsed by calling the parse() method on this >>>>>> instance? What we want to have is a syntax tree of the statement >>>>>> that allows us to see which tables and which fields are accessed / >>>>>> included in the statement (including any possibly done "renames" á >>>>>> la SELECT street AS "ADDRESS" FROM USER_DATA ). >>>>>> >>>>>> The problem is, that we are stuck ... we spent several days now to >>>>>> try to find the proper way to create an instance of the Parser. Is >>>>>> it possible at all without having to set up a running derby system? >>>>>> >>>>>> Is the Monitor class the right entry point? How can we create a >>>>>> CompilerContext so that a Parser instance can be created? >>>>>> >>>>>> >>>>>> This sure is off-topic but we don't see any way through all this. >>>>>> Can you help us? >>>>>> >>>>>> >>>>>> Thanks in advance >>>>>> >>>>>> Christian >>>>>> >>>>> >>>>> >>>> >>> >>> >> > > -- To reply to this posting directly use the following address and remove the 'NO-SPAM' part: Riedel.Christian.NO-SPAM@... |
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Re: Using derby to parse an SQL statement
by Rick Hillegas-2
::
Rate this Message:
Hi Christian,
Thanks for the additional context on the problem you are tackling. Some comments inline... Christian Riedel wrote: > Hi Rick, > > as requested I want to report our findings when working with the parser: > > Background: we want to use the parser to analyze SQL statements that > are generated by different tools, for example an ETL tool. It seems > that, depending on the DBMS the tools are configured to work with, the > generated SQL is not completely standard conform, which causes a > parser exception. > > As example the statement > > select null "a_null_column", id "an_id_column" from a_table > > runs fine on an MSSQL DB, but causes problems on a DB2. > > Feeding the parser with this statement brings up a parsing exception. > Supposedly because it is not SQL standard conform. > > Our question is: Does the derby parser "only" understand standard SQL > or can it be instructed to accept DB2, Oracle, MSSQL etc. specific > syntax as well? supposed to be a subset of standard SQL. In the past several years, the community has interpreted that to mean the 2003 version of the SQL standard. Of course, Derby is not completely compliant, but we try hard. Derby also understands some bits of the DB2 dialect. Derby hasn't been taught any Oracle-specific or MSSQL-specific syntax that I'm aware of. You might be able to hack up the Derby parser so that it understands bits of these other dialects. Alternatively, using the current parser as any example, you might be able to write some other parsers which digest DB2, Oracle, and MSSQL syntax and turn out Derby ASTs. I think that you could hack up CompilerContextImpl.getParser() to return different parsers depending on the setting of an environment variable. This sounds like a lot of work to me. In addition, I don't know enough about the peculiarities of those other dialects to be able to say whether Derby's set of AST nodes is rich enough to express DB2, Oracle, and MSSQL's languages. So the short answer to your question is this: using Derby's parser, all that you can expect to parse is a fairly large subset of standard SQL. Hope this helps, -Rick > > Other than this we have not had any problems with the parser. Using > the Derby AST brings the information we wanted. > > > I hope you can help us with this problem as well. > > > Regards > > Christian > > > Rick Hillegas schrieb: >> Hi Christian, >> >> I have checked the patch into the development trunk. At this point, >> you will automatically get the fix if you build an up-to-date copy of >> the trunk. Please let us know what your experience is. You will >> notice from the discussion on the JIRA that some syntax may not >> work--this is because the separation between the parsing and >> name-resolution phases is not as clean as it should be. The JIRA >> would be a good place for you to record your observations. >> >> Thanks, >> -Rick >> >> Christian Riedel wrote: >>> Hi Rick, >>> >>> at first thank you very much for your efforts so far. At a first >>> glance your changes to the code seem to be exactly what we want. I >>> will try if it works asap. >>> >>> To test it with the derby libs I'd have to work on the current trunk >>> and apply the patch an then compile derby manually, right? >>> >>> I'll keep you updated >>> >>> Thanks for your help >>> >>> Christian >>> >>> Rick Hillegas schrieb: >>>> Hi Christian, >>>> >>>> I have created a JIRA to track this issue: >>>> https://issues.apache.org/jira/browse/DERBY-3946 >>>> >>>> I have attached to the JIRA a small patch which exposes the AST >>>> produced by the parser. I have also attached a simple program, >>>> ASTParser, which shows how to retrieve the AST from Derby. I am >>>> inclined to check this patch in to the trunk. Please let me know if >>>> you find this useful and if you would like me to port this patch to >>>> another Derby branch. >>>> >>>> Hope this helps, >>>> -Rick >>>> >>>> Christian Riedel wrote: >>>>> Hi Rick, >>>>> >>>>> first of all thanks for your answer ... now the relations have >>>>> become a lot clearer ... >>>>> >>>>> Your are right, there is a lot of things to be done that we >>>>> probably don't want to go through. You asked why we cannot take >>>>> the whole derby engine and use it ... well there is nor real >>>>> reason not to do so. The only "problem" I see is, that derby is a >>>>> dbms - if I am not mistaken - and we only have an SQL statement >>>>> that we extract from a text file and want tot analyze it to >>>>> extract some metadata from it. >>>>> >>>>> So if we take the derby engine as it is, how can I prevent that we >>>>> have to set up a "dummy" DB in order to be able to actually use >>>>> thje parsing feature .... >>>>> >>>>> I hope you see my point. >>>>> >>>>> We could live with setting up a dummy DB ... and I do think that >>>>> the derby AST offers all information we need. It's just that I >>>>> don't see how we can set this thing up. So having a dummy DB is >>>>> necessary to be able to intercept the parsing process to get hold >>>>> of the AST? Can we actually access the AST if we choose to set up >>>>> a dummy DB? I think that would be something we could live with ;-) >>>>> >>>>> >>>>> Thanks for your support >>>>> >>>>> Christian >>>>> >>>>> >>>>> Rick Hillegas schrieb: >>>>>> Hi Christian, >>>>>> >>>>>> I think you will have difficulty isolating the Parser from the >>>>>> rest of the SQL interpreter. In theory, you should be able to >>>>>> isolate the compiler from the execution engine and the storage >>>>>> layer--but that is an untested theory. >>>>>> >>>>>> The Parser wants to turn out abstract syntax trees (AST). >>>>>> Ideally, the Parser would just need to ask a NodeFactory for AST >>>>>> nodes and you could supply your own NodeFactory. But I think that >>>>>> there is a fair amount of coupling between the Parser and Derby's >>>>>> concrete implementation of NodeFactory. I think that you could >>>>>> uncouple the two, but you may not want to spend your time on that. >>>>>> >>>>>> So the Parser is going to force you to pull in the AST nodes. >>>>>> Once you do that, you will end up with the whole compiler. In >>>>>> particular, the AST nodes (and the Parser itself) expect that you >>>>>> will supply an implementation of LanguageConnectionContext, the >>>>>> master state variable for the whole SQL interpreter. Untangling >>>>>> that requirement is another chunk of work you may not want to do. >>>>>> >>>>>> Then there is the Monitor. It has been a while since I was in >>>>>> that code but I seem to recall that fairly early on the Monitor >>>>>> wants to fault in a storage layer. In theory you ought to be able >>>>>> to supply the Monitor a list of modules that doesn't include a >>>>>> storage layer. But since no-one runs in this configuration, there >>>>>> are probably a lot of undocumented surprises that you may not >>>>>> want to fix either. >>>>>> >>>>>> Can I ask you what breaks if you just pull in the whole Derby >>>>>> engine? Are you concerned that you will fault in too much code >>>>>> that you barely use? Are you concerned that you'll end up with a >>>>>> dummy database that you don't need? Are Derby's AST nodes not a >>>>>> usable representation of statement syntax? >>>>>> >>>>>> Thanks, >>>>>> -Rick >>>>>> >>>>>> Christian Riedel wrote: >>>>>>> Hi there, >>>>>>> >>>>>>> we are working on a small project where we need to analyze an >>>>>>> SQL statement that can be of any kind: very simple, with inner >>>>>>> selects, complex join etc. >>>>>>> >>>>>>> We figured it inappropriate to start to write our own parser >>>>>>> when there are other projects, like derby, out there that can do >>>>>>> it much better than we would possibly do ... so this was our idea: >>>>>>> >>>>>>> Can we use derby to create an instance of Parser >>>>>>> (org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL >>>>>>> statement be parsed by calling the parse() method on this >>>>>>> instance? What we want to have is a syntax tree of the statement >>>>>>> that allows us to see which tables and which fields are accessed >>>>>>> / included in the statement (including any possibly done >>>>>>> "renames" á la SELECT street AS "ADDRESS" FROM USER_DATA ). >>>>>>> >>>>>>> The problem is, that we are stuck ... we spent several days now >>>>>>> to try to find the proper way to create an instance of the >>>>>>> Parser. Is it possible at all without having to set up a running >>>>>>> derby system? >>>>>>> >>>>>>> Is the Monitor class the right entry point? How can we create a >>>>>>> CompilerContext so that a Parser instance can be created? >>>>>>> >>>>>>> >>>>>>> This sure is off-topic but we don't see any way through all >>>>>>> this. Can you help us? >>>>>>> >>>>>>> >>>>>>> Thanks in advance >>>>>>> >>>>>>> Christian >>>>>>> >>>>>> >>>>>> >>>>> >>>> >>>> >>> >> >> > |
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