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Handling Multiple Databases
by Norman Elton
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I've got an application that connects to one of a series of database
servers. I need to programmatically say, "drop all your connections and change to server X". So far, I see two methods to accomplish this: - Somehow make a ConnectionFactory-esque class that generates connections to the "active" server. I'm not entirely sure how this would integrate into c3p0. From there, I could call a softReset whenever the "active" server changes. Some sort of ConnectionChecker could reinforce this. - Use multiple, stand-alone instances of ComboPooledDataSource, each connecting to a single server. My application would draw a connection from whichever pool was "active". The first implementation seems the cleanest, since there wouldn't be redundancy in the helper threads, etc. But I'm a little foggy on where to start. Would I generate multiple DriverManagerDataSources, then a single WrapperConnectionPoolDataSource, and using setNestedDataSource to swap out the "active" datasource? The second implementation is more straight-forward. But how much penalty am I incurring by managing two to four concurrent ComboPoolDataSources? Thanks! Norman ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ c3p0-users mailing list c3p0-users@... https://lists.sourceforge.net/lists/listinfo/c3p0-users |
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Re: Handling Multiple Databases
by Steve Waldman
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Why not just destroy DataSources to the old DB and create a DataSource
on the new DB as needed? [ You could easily wrap the logic of this into a factory method, MyDataSourceFactory.switchTo(String jdcUrl, Properties props), something like that. ] smiles, Steve On Jun 11, 2009, at 8:06 PM, Norman Elton wrote: > I've got an application that connects to one of a series of database > servers. I need to programmatically say, "drop all your connections > and change to server X". So far, I see two methods to accomplish this: > > - Somehow make a ConnectionFactory-esque class that generates > connections to the "active" server. I'm not entirely sure how this > would integrate into c3p0. From there, I could call a softReset > whenever the "active" server changes. Some sort of ConnectionChecker > could reinforce this. > > - Use multiple, stand-alone instances of ComboPooledDataSource, each > connecting to a single server. My application would draw a connection > from whichever pool was "active". > > The first implementation seems the cleanest, since there wouldn't be > redundancy in the helper threads, etc. But I'm a little foggy on where > to start. Would I generate multiple DriverManagerDataSources, then a > single WrapperConnectionPoolDataSource, and using setNestedDataSource > to swap out the "active" datasource? > > The second implementation is more straight-forward. But how much > penalty am I incurring by managing two to four concurrent > ComboPoolDataSources? > > Thanks! > > Norman > > ------------------------------------------------------------------------------ > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables unlimited > royalty-free distribution of the report engine for externally facing > server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > c3p0-users mailing list > c3p0-users@... > https://lists.sourceforge.net/lists/listinfo/c3p0-users ~oo~ Steve Waldman swaldman@... ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ c3p0-users mailing list c3p0-users@... https://lists.sourceforge.net/lists/listinfo/c3p0-users |
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Re: Handling Multiple Databases
by Norman Elton
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Do you mean completely tear down and recreate the
ComboPooledDataSource? This seems a little drastic, although I guess it would work. Ideally, I'd like the connection pool to keep going, but empty itself and start creating connections to the new database. I suppose, functionally, they're the same thing. But the latter would allow me to do a softReset so that existing connections continue to work until they're returned. Admittedly, I'm still wrapping my head around the terminology here (just started with c3p0 today!), maybe I'm missing something obvious? Thanks for your help, Norman On Thu, Jun 11, 2009 at 1:49 PM, Steve Waldman<swaldman@...> wrote: > Why not just destroy DataSources to the old DB and create a DataSource on > the new DB as needed? [ You could easily wrap the logic of this into a > factory method, MyDataSourceFactory.switchTo(String jdcUrl, Properties > props), something like that. ] > > smiles, > Steve > > > On Jun 11, 2009, at 8:06 PM, Norman Elton wrote: > >> I've got an application that connects to one of a series of database >> servers. I need to programmatically say, "drop all your connections >> and change to server X". So far, I see two methods to accomplish this: >> >> - Somehow make a ConnectionFactory-esque class that generates >> connections to the "active" server. I'm not entirely sure how this >> would integrate into c3p0. From there, I could call a softReset >> whenever the "active" server changes. Some sort of ConnectionChecker >> could reinforce this. >> >> - Use multiple, stand-alone instances of ComboPooledDataSource, each >> connecting to a single server. My application would draw a connection >> from whichever pool was "active". >> >> The first implementation seems the cleanest, since there wouldn't be >> redundancy in the helper threads, etc. But I'm a little foggy on where >> to start. Would I generate multiple DriverManagerDataSources, then a >> single WrapperConnectionPoolDataSource, and using setNestedDataSource >> to swap out the "active" datasource? >> >> The second implementation is more straight-forward. But how much >> penalty am I incurring by managing two to four concurrent >> ComboPoolDataSources? >> >> Thanks! >> >> Norman >> >> >> ------------------------------------------------------------------------------ >> Crystal Reports - New Free Runtime and 30 Day Trial >> Check out the new simplified licensing option that enables unlimited >> royalty-free distribution of the report engine for externally facing >> server and web deployment. >> http://p.sf.net/sfu/businessobjects >> _______________________________________________ >> c3p0-users mailing list >> c3p0-users@... >> https://lists.sourceforge.net/lists/listinfo/c3p0-users > > ~oo~ > Steve Waldman > swaldman@... > > > > ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ c3p0-users mailing list c3p0-users@... https://lists.sourceforge.net/lists/listinfo/c3p0-users |
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Re: Handling Multiple Databases
by Steve Waldman
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> Call me crazy, but I may have found an even simpler way. It looks like
> if I just call .setJdbcUrl() on my ComboPooledDataSource, it calls a > softReset (technically, this.resetPoolManager(false)) and > reinitializes the pool. > > Do you see any problems just changing the URL and marching on? No, that's true. If you change any of the core config params, it soft resets to ensure the change takes uniformly. That's a perfectly fine idea, elegant and simple. smiles, Steve On Jun 11, 2009, at 11:01 PM, Norman Elton wrote: > Call me crazy, but I may have found an even simpler way. It looks like > if I just call .setJdbcUrl() on my ComboPooledDataSource, it calls a > softReset (technically, this.resetPoolManager(false)) and > reinitializes the pool. > > Do you see any problems just changing the URL and marching on? > > Thanks, > > Norman > > On Thu, Jun 11, 2009 at 2:08 PM, Steve Waldman<swaldman@...> > wrote: >> In terms of overhead, I'd think that next to tearing down the >> Connections, >> tearing down the DataSource is pretty much negligible. And you want >> to tear >> down the Connection -- you said you'd prefer not to maintain the >> overhead of >> several unused pools (that would be the fastest approach, but would >> use a >> bit more memory and network resources). Alternatively you could >> keep several >> DataSources open, and just set minPoolSize=1, letting the pool grow >> when you >> shift from one DB to the next. >> >> But my guess is the simplest solution, tear down and recreate, will >> be best >> unless you are switching databases with great frequency. If >> minPoolSize >> isn't huge and you don't switch more often than say once in 10 >> mins, I think >> the benefits of simplicity are likely to overwhelm any small gains in >> efficiency. (If you are switching frequently, don't softReset() >> either, cuz >> you'll incur the overhead of all the Cxn destruction and >> recreation. If you >> need to shift constantly, then you do need to keep a set of >> DataSources live >> and active.) >> >> smiles, >> Steve >> >> > > ------------------------------------------------------------------------------ > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables unlimited > royalty-free distribution of the report engine for externally facing > server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > c3p0-users mailing list > c3p0-users@... > https://lists.sourceforge.net/lists/listinfo/c3p0-users ~oo~ Steve Waldman swaldman@... ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ c3p0-users mailing list c3p0-users@... https://lists.sourceforge.net/lists/listinfo/c3p0-users |
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Re: Handling Multiple Databases
by Norman Elton
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Steve,
I'm beginning to dabble in Hibernate, and this may be a question for the hibernate mailing list... I see that Hibernate has native support for c3p0. But can I access the DataSource to twiddle settings like JdbcUrl when it's all wrapped up inside Hibernate? Thanks! Norman On Thu, Jun 11, 2009 at 4:08 PM, Steve Waldman<swaldman@...> wrote: >> Call me crazy, but I may have found an even simpler way. It looks like >> if I just call .setJdbcUrl() on my ComboPooledDataSource, it calls a >> softReset (technically, this.resetPoolManager(false)) and >> reinitializes the pool. >> >> Do you see any problems just changing the URL and marching on? > > > No, that's true. If you change any of the core config params, it soft resets > to ensure the change takes uniformly. That's a perfectly fine idea, elegant > and simple. > > smiles, > Steve > > > On Jun 11, 2009, at 11:01 PM, Norman Elton wrote: > >> Call me crazy, but I may have found an even simpler way. It looks like >> if I just call .setJdbcUrl() on my ComboPooledDataSource, it calls a >> softReset (technically, this.resetPoolManager(false)) and >> reinitializes the pool. >> >> Do you see any problems just changing the URL and marching on? >> >> Thanks, >> >> Norman >> >> On Thu, Jun 11, 2009 at 2:08 PM, Steve Waldman<swaldman@...> >> wrote: >>> >>> In terms of overhead, I'd think that next to tearing down the >>> Connections, >>> tearing down the DataSource is pretty much negligible. And you want to >>> tear >>> down the Connection -- you said you'd prefer not to maintain the overhead >>> of >>> several unused pools (that would be the fastest approach, but would use a >>> bit more memory and network resources). Alternatively you could keep >>> several >>> DataSources open, and just set minPoolSize=1, letting the pool grow when >>> you >>> shift from one DB to the next. >>> >>> But my guess is the simplest solution, tear down and recreate, will be >>> best >>> unless you are switching databases with great frequency. If minPoolSize >>> isn't huge and you don't switch more often than say once in 10 mins, I >>> think >>> the benefits of simplicity are likely to overwhelm any small gains in >>> efficiency. (If you are switching frequently, don't softReset() either, >>> cuz >>> you'll incur the overhead of all the Cxn destruction and recreation. If >>> you >>> need to shift constantly, then you do need to keep a set of DataSources >>> live >>> and active.) >>> >>> smiles, >>> Steve >>> >>> >> >> >> ------------------------------------------------------------------------------ >> Crystal Reports - New Free Runtime and 30 Day Trial >> Check out the new simplified licensing option that enables unlimited >> royalty-free distribution of the report engine for externally facing >> server and web deployment. >> http://p.sf.net/sfu/businessobjects >> _______________________________________________ >> c3p0-users mailing list >> c3p0-users@... >> https://lists.sourceforge.net/lists/listinfo/c3p0-users > > ~oo~ > Steve Waldman > swaldman@... > > > > ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ c3p0-users mailing list c3p0-users@... https://lists.sourceforge.net/lists/listinfo/c3p0-users |
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Re: Handling Multiple Databases
by Steve Waldman
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Norman,
In newer versions of hibernate, you should be able to set arbitrary c3p0 params in hibernate's config (it used to be that you could only set five params that hibernate specifically exposed). however, the datasource itself is buried, so harder to get at programmatically. Fortunately, you can always find c3p0 DataSources using the C3P0Registry class. See the API docs. smiles, Steve On Jun 17, 2009, at 6:15 AM, Norman Elton wrote: > Steve, > > I'm beginning to dabble in Hibernate, and this may be a question for > the hibernate mailing list... I see that Hibernate has native support > for c3p0. But can I access the DataSource to twiddle settings like > JdbcUrl when it's all wrapped up inside Hibernate? > > Thanks! > > Norman > > > > On Thu, Jun 11, 2009 at 4:08 PM, Steve Waldman<swaldman@...> > wrote: >>> Call me crazy, but I may have found an even simpler way. It looks >>> like >>> if I just call .setJdbcUrl() on my ComboPooledDataSource, it calls a >>> softReset (technically, this.resetPoolManager(false)) and >>> reinitializes the pool. >>> >>> Do you see any problems just changing the URL and marching on? >> >> >> No, that's true. If you change any of the core config params, it >> soft resets >> to ensure the change takes uniformly. That's a perfectly fine idea, >> elegant >> and simple. >> >> smiles, >> Steve >> >> >> On Jun 11, 2009, at 11:01 PM, Norman Elton wrote: >> >>> Call me crazy, but I may have found an even simpler way. It looks >>> like >>> if I just call .setJdbcUrl() on my ComboPooledDataSource, it calls a >>> softReset (technically, this.resetPoolManager(false)) and >>> reinitializes the pool. >>> >>> Do you see any problems just changing the URL and marching on? >>> >>> Thanks, >>> >>> Norman >>> >>> On Thu, Jun 11, 2009 at 2:08 PM, Steve Waldman<swaldman@...> >>> wrote: >>>> >>>> In terms of overhead, I'd think that next to tearing down the >>>> Connections, >>>> tearing down the DataSource is pretty much negligible. And you >>>> want to >>>> tear >>>> down the Connection -- you said you'd prefer not to maintain the >>>> overhead >>>> of >>>> several unused pools (that would be the fastest approach, but >>>> would use a >>>> bit more memory and network resources). Alternatively you could >>>> keep >>>> several >>>> DataSources open, and just set minPoolSize=1, letting the pool >>>> grow when >>>> you >>>> shift from one DB to the next. >>>> >>>> But my guess is the simplest solution, tear down and recreate, >>>> will be >>>> best >>>> unless you are switching databases with great frequency. If >>>> minPoolSize >>>> isn't huge and you don't switch more often than say once in 10 >>>> mins, I >>>> think >>>> the benefits of simplicity are likely to overwhelm any small >>>> gains in >>>> efficiency. (If you are switching frequently, don't softReset() >>>> either, >>>> cuz >>>> you'll incur the overhead of all the Cxn destruction and >>>> recreation. If >>>> you >>>> need to shift constantly, then you do need to keep a set of >>>> DataSources >>>> live >>>> and active.) >>>> >>>> smiles, >>>> Steve >>>> >>>> >>> >>> >>> ------------------------------------------------------------------------------ >>> Crystal Reports - New Free Runtime and 30 Day Trial >>> Check out the new simplified licensing option that enables unlimited >>> royalty-free distribution of the report engine for externally facing >>> server and web deployment. >>> http://p.sf.net/sfu/businessobjects >>> _______________________________________________ >>> c3p0-users mailing list >>> c3p0-users@... >>> https://lists.sourceforge.net/lists/listinfo/c3p0-users >> >> ~oo~ >> Steve Waldman >> swaldman@... >> >> >> >> > > ------------------------------------------------------------------------------ > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables unlimited > royalty-free distribution of the report engine for externally facing > server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > c3p0-users mailing list > c3p0-users@... > https://lists.sourceforge.net/lists/listinfo/c3p0-users ~oo~ Steve Waldman swaldman@... ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ c3p0-users mailing list c3p0-users@... https://lists.sourceforge.net/lists/listinfo/c3p0-users |
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