Nabble - J

Re: JDB Error Handling Bug? (WAS: RE: Newbie JDB problem: inserting chars in a 1 column char table gives 'assertion failure')

2009-12-17T01:43:09Z

Working on it some more, I am more convinced that this is a bug. Since, you would not be able to simulate this problem if you have more than one column like so:
ht=: Create__db 'tblTest';0 : 0
Field1 int
Field2 varchar
)
Insert__db 'tblTest';<0;'a'
Reads__db 'from tblTest'
+------+------+
|Field1|Field2|
+------+------+
|0 |a |
+------+------+
Insert__db 'tblTest';<0 1 ;<;:'aa bb'
Reads__db 'from tblTest'
+------+------+
|Field1|Field2|
+------+------+
|0 |a |
|0 |aa |
|1 |bb |
+------+------+

NB. Now we try to make insert fail:
Insert__db 'tblTest';<'aa bb'
|Insert rows required items: 2, given items: 1: throw
| throw msg
Insert__db 'tblTest';<'aa'
|Insert rows required items: 2, given items: 1: throw
| throw msg
Reads__db 'from tblTest'
+------+------+
|Field1|Field2|
+------+------+
|0 |a |
|0 |aa |
|1 |bb |
+------+------+
+------+------+
|Field1|Field2|
+------+------+
|0 |a |
|0 |aa |
|1 |bb |
+------+------+
Insert__db 'tblTest';<10;<;:'xy e4 dty'
|assertion failure: validate
| 1=#~.(#@".)&>'active';Tcolmap
Reads__db 'from tblTest'
+------+------+
|Field1|Field2|
+------+------+
| 0 |a |
| 0 |aa |
| 1 |bb |
|10 |xy |
+------+------+

As you can see from above, the code was able to handle columns insert of different sizes by only handling the first "valid" rows.

-----Original Message-----
From: programming-bounces@... [mailto:programming-bounces@...] On Behalf Of Alex Rufon
Sent: Thursday, December 17, 2009 5:47 PM
To: Programming forum
Subject: [Jprogramming] JDB Error Handling Bug? (WAS: RE: Newbie JDB problem: inserting chars in a 1 column char table gives 'assertion failure')

I've been trying out Chris Collins code and I believe there may be a bug. So here is my J session.
NB. =========================================================
NB. Start of J session
load 'data/jdb'
[ffd=: Open_jdb_ jpath '~temp'
+-+
|1|
+-+
Drop__ffd 'testdb'
[db=: Create__ffd 'testdb'
+-+
|2|
+-+
ht=: Create__db 'tblVarChar';0 : 0
field1 varchar
)
ht
+-+
|3|
+-+

NB. At this point, we know that my server locale is 1, my database locale is 2 and the table 'tblVarChar' is in locale 3.
NB. I'm going to insert a sequence of data and read the table immediately
Insert__db 'tblVarChar';'a'
Read__db 'from tblVarChar'
+------+---+
|field1|+-+|
| ||a||
| |+-+|
+------+---+
;:'bb ccc dddd eeeee ffffff'
+--+---+----+-----+------+
|bb|ccc|dddd|eeeee|ffffff|
+--+---+----+-----+------+
Insert__db 'tblVarChar';<<;:'bb ccc dddd eeeee ffffff'
Read__db 'from tblVarChar'
+------+----------------------------+
|field1|+-+--+---+----+-----+------+|
| ||a|bb|ccc|dddd|eeeee|ffffff||
| |+-+--+---+----+-----+------+|
+------+----------------------------+
NB. Up to this point, everything is going well, not I am going to force the JDB Insert method to fail by inserting
NB. data in a format that it did not expect
Insert__db 'tblVarChar';<'zz'
|assertion failure: validate
| 1=#~.(#@".)&>'active';Tcolmap
Read__db 'from tblVarChar'
|index error: readbase1
| (rws{".)&.>cls

NB. End of J Session
NB. =========================================================

I believe that the data itself is not corrupted because the data can still be seen there (note that 'zz' was saved)
c2__ht
+-+--+---+----+-----+------+--+
|a|bb|ccc|dddd|eeeee|ffffff|zz|
+-+--+---+----+-----+------+--+

From what I remember from the discussions, JDB is transactional ... is there a way to rollback?

I feel that this should be considered a bug.

r/Alex

-----Original Message-----
From: programming-bounces@... [mailto:programming-bounces@...] On Behalf Of christopher collins
Sent: Thursday, December 17, 2009 2:12 PM
To: programming@...
Subject: [Jprogramming] Newbie JDB problem: inserting chars in a 1 column char table gives 'assertion failure'

Thanks to all for your help, especially Mr. Lam.
Your response, Mr. Lam, was very instructive.
I used your input to explore a bit more, with a couple of questions arising.

See the questions embedded below:

*****************************
load 'data/jdb'

ffd =: Open_jdb_ jpath , '~temp'

Drop__ffd 'testdb'
db =: Create__ffd 'testdb'

ht=: Create__db 'tblChar';0 : 0
c1 char
)

NB. JDB doc says a 'char' column is stored as a character matrix
NB. The next sentence works, even though it inserts a scalar, 'a'
NB. QUESTION: Is this contrary to the JDB doc?
Insert__db 'tblChar';'a'
]shape =. $'a'
NB. Inserts a list of shape 1
Insert__db 'tblChar';,'b'
]shape =. $ ,'b'
NB. Inserts a list of shape 3 1
Insert__db 'tblChar';,.'def'
]shape =. $ ,.'def'
NB. Inserts a list of shape 1 4
Insert__db 'tblChar';,:'ghih'
]shape =. $ ,:'ghih'
Insert__db 'tblChar';3 5 $'123457'
Insert__db 'tblChar';,:'012345678901234567890'
]shape=.$ ,:'012345678901234567890'
NB. A JDB 'char' column allows chars of varying lengths to be inserted
Insert__db 'tblChar';2 100$'1234567890'
Reads__db 'from tblChar'

NB. The insert below causes a failure
NB. After this the table can no longer be read.
NB. QUESTION: Is that behavior intended?
NB. If so, JDB seems a little fragile for the rough, unskilled hands
of newbies like me
NB. This insert, where '01' is a list of shape 2, fails even though an
insert of 'b', a list of shape 1 worked above.
NB. QUESTION: Is this behavior consistent in a way that I am not understanding?
Insert__db 'tblChar';'01'
Reads__db 'from tblChar'

Thanks again for the high quality help & instruction.
--chris--
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Nabble - J

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