Обсуждение: Patch for streaming resultsets
Hello folks, I've made a patch against the current CVS version of the JDBC driver, which, based upon Nick Ferrier's patch (thanks!), which adds streaming result sets to the driver. I've made some modifications to the build file, too, as in it's current version it's not able to build clean for JDBC3. I think I fixed that. Another thing I added are three properties which can be included inside the URL: defaultFetchSize=<int> sets the fetch size default to <int>. forceFetchSize=<boolean> in case this property is true, the driver ignores all setFetchSize() API calls from the application. It can be used to get apps, which "know" the postgres driver, work though... :-) useServerPrepare=<never|always> This on alters the behaviour of server prepared statements. The default behaviour is that PreparedStatement's DO get prepared on server side, and normal Statement's do NOT. Setting this property to "never" switches server side preparation off completely, whereas setting it to always even makes normal Statements prepared ones (which can be nice in case of ever and ever repeated queries such as queue lookups). Please note that some parts of the source are commented out for now, as I did not find a way to accomplish the declaration of a cursor for a prepared statement. As for now, this seems to be a feature in upcoming 7.3.2/7.4. But as soon as one of these arrive, we just twig out these comments and there we go... The patch is, as mentioned above, against the most actual CVS version. A single file, PGResultSet.java, belongs into the org/postgresql directory; it needs to be added to the repository. Again, a big thank you for Nick Ferrier, as he made the first version of this; I cleaned it up and tested it quite thoroughly, our own app as all of the test cases seem to work flawlessly with it. It seems that I've broken not too much... :-) have fun, Patric
Вложения
Patric, Can you clarify why you want the default behaviour to use server prepared statements? I use prepared statements just because they are easier, not because of any inherent behaviour. Dave On Thu, 2003-01-02 at 11:33, Patric Bechtel wrote: > Hello folks, > > I've made a patch against the current CVS version of the JDBC driver, > which, based upon Nick Ferrier's patch (thanks!), which adds > streaming result sets to the driver. > I've made some modifications to the build file, too, as in it's > current version it's not able to build clean for JDBC3. I think > I fixed that. > Another thing I added are three properties which can be included > inside the URL: > > defaultFetchSize=<int> > > sets the fetch size default to <int>. > > forceFetchSize=<boolean> > > in case this property is true, the driver ignores all setFetchSize() > API calls from the application. It can be used to get apps, which > "know" the postgres driver, work though... :-) > > useServerPrepare=<never|always> > > This on alters the behaviour of server prepared statements. The > default behaviour is that PreparedStatement's DO get prepared > on server side, and normal Statement's do NOT. > Setting this property to "never" switches server side preparation > off completely, whereas setting it to always even makes > normal Statements prepared ones (which can be nice in case of > ever and ever repeated queries such as queue lookups). > > Please note that some parts of the source are commented out > for now, as I did not find a way to accomplish the declaration > of a cursor for a prepared statement. As for now, this seems > to be a feature in upcoming 7.3.2/7.4. But as soon as one of > these arrive, we just twig out these comments and there we go... > > The patch is, as mentioned above, against the most actual CVS > version. A single file, PGResultSet.java, belongs into the > org/postgresql directory; it needs to be added to the > repository. > > Again, a big thank you for Nick Ferrier, as he made the first > version of this; I cleaned it up and tested it quite > thoroughly, our own app as all of the test cases seem to work > flawlessly with it. It seems that I've broken not too much... :-) > > have fun, > > Patric > > > > ______________________________________________________________________ > > ---------------------------(end of broadcast)--------------------------- > TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org -- Dave Cramer <Dave@micro-automation.net>
On 03 Jan 2003 09:30:18 -0500, Dave Cramer wrote: Dave, that's what the useServerPrepare URL property is for. Anyone not liking (or sort of...) the behaviour of the driver can alter it so that prepared statements NEVER get prepared on the server. You can still use setUseServerPrepared(true) to alter this again for eg. one special query, but the default then is never (or always). The JDBC API only differentiates between Statements and Prepared Statements, which is a bit poor for us Postgres users. Normally (I'm speaking in M$ or DB/2 conventions) its ALWAYS no difference between prepare statements or ad hoc execution. If you then reuse the prepared statement thereafter, the optimizer knows what to do and you'll get a performance win. That should be the same on Postgres (and later will be that way, I'm sure...). But for the moment, there's a small chance, that prepared statements get not really optimized to the very last bit, which normally isn't that bad as it first sounds like. But if you repeatadly execute a prepared statement over and over, you'll win; less preparation time on the client, less on the server, so you make the bet. We could even vote if prepared statements by default get prepared on the server or not. I could easily change the behaviour. My +1 for the current behaviour of my patch. :-) tia Patric >Patric, > >Can you clarify why you want the default behaviour to use server >prepared statements? > >I use prepared statements just because they are easier, not because of >any inherent behaviour. > > >Dave > >On Thu, 2003-01-02 at 11:33, Patric Bechtel wrote: >> Hello folks, >> >> I've made a patch against the current CVS version of the JDBC driver, >> which, based upon Nick Ferrier's patch (thanks!), which adds >> streaming result sets to the driver. >> I've made some modifications to the build file, too, as in it's >> current version it's not able to build clean for JDBC3. I think >> I fixed that. >> Another thing I added are three properties which can be included >> inside the URL: >> >> defaultFetchSize=<int> >> >> sets the fetch size default to <int>. >> >> forceFetchSize=<boolean> >> >> in case this property is true, the driver ignores all setFetchSize() >> API calls from the application. It can be used to get apps, which >> "know" the postgres driver, work though... :-) >> >> useServerPrepare=<never|always> >> >> This on alters the behaviour of server prepared statements. The >> default behaviour is that PreparedStatement's DO get prepared >> on server side, and normal Statement's do NOT. >> Setting this property to "never" switches server side preparation >> off completely, whereas setting it to always even makes >> normal Statements prepared ones (which can be nice in case of >> ever and ever repeated queries such as queue lookups). >> >> Please note that some parts of the source are commented out >> for now, as I did not find a way to accomplish the declaration >> of a cursor for a prepared statement. As for now, this seems >> to be a feature in upcoming 7.3.2/7.4. But as soon as one of >> these arrive, we just twig out these comments and there we go... >> >> The patch is, as mentioned above, against the most actual CVS >> version. A single file, PGResultSet.java, belongs into the >> org/postgresql directory; it needs to be added to the >> repository. >> >> Again, a big thank you for Nick Ferrier, as he made the first >> version of this; I cleaned it up and tested it quite >> thoroughly, our own app as all of the test cases seem to work >> flawlessly with it. It seems that I've broken not too much... :-) >> >> have fun, >> >> Patric >> >> >> >> ______________________________________________________________________ >> >> ---------------------------(end of broadcast)--------------------------- >> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org >-- >Dave Cramer <Dave@micro-automation.net> > > >---------------------------(end of broadcast)--------------------------- >TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) > >
On 03 Jan 2003 09:30:18 -0500, Dave Cramer wrote: Dave, that's what the useServerPrepare URL property is for. Anyone not liking (or sort of...) the behaviour of the driver can alter it so that prepared statements NEVER get prepared on the server. You can still use setUseServerPrepared(true) to alter this again for eg. one special query, but the default then is never (or always). The JDBC API only differentiates between Statements and Prepared Statements, which is a bit poor for us Postgres users. Normally (I'm speaking in M$ or DB/2 conventions) its ALWAYS no difference between prepare statements or ad hoc execution. If you then reuse the prepared statement thereafter, the optimizer knows what to do and you'll get a performance win. That should be the same on Postgres (and later will be that way, I'm sure...). But for the moment, there's a small chance, that prepared statements get not really optimized to the very last bit, which normally isn't that bad as it first sounds like. But if you repeatadly execute a prepared statement over and over, you'll win; less preparation time on the client, less on the server, so you make the bet. We could even vote if prepared statements by default get prepared on the server or not. I could easily change the behaviour. My +1 for the current behaviour of my patch. :-) tia Patric >Patric, > >Can you clarify why you want the default behaviour to use server >prepared statements? > >I use prepared statements just because they are easier, not because of >any inherent behaviour. > > >Dave > >On Thu, 2003-01-02 at 11:33, Patric Bechtel wrote: >> Hello folks, >> >> I've made a patch against the current CVS version of the JDBC driver, >> which, based upon Nick Ferrier's patch (thanks!), which adds >> streaming result sets to the driver. >> I've made some modifications to the build file, too, as in it's >> current version it's not able to build clean for JDBC3. I think >> I fixed that. >> Another thing I added are three properties which can be included >> inside the URL: >> >> defaultFetchSize=<int> >> >> sets the fetch size default to <int>. >> >> forceFetchSize=<boolean> >> >> in case this property is true, the driver ignores all setFetchSize() >> API calls from the application. It can be used to get apps, which >> "know" the postgres driver, work though... :-) >> >> useServerPrepare=<never|always> >> >> This on alters the behaviour of server prepared statements. The >> default behaviour is that PreparedStatement's DO get prepared >> on server side, and normal Statement's do NOT. >> Setting this property to "never" switches server side preparation >> off completely, whereas setting it to always even makes >> normal Statements prepared ones (which can be nice in case of >> ever and ever repeated queries such as queue lookups). >> >> Please note that some parts of the source are commented out >> for now, as I did not find a way to accomplish the declaration >> of a cursor for a prepared statement. As for now, this seems >> to be a feature in upcoming 7.3.2/7.4. But as soon as one of >> these arrive, we just twig out these comments and there we go... >> >> The patch is, as mentioned above, against the most actual CVS >> version. A single file, PGResultSet.java, belongs into the >> org/postgresql directory; it needs to be added to the >> repository. >> >> Again, a big thank you for Nick Ferrier, as he made the first >> version of this; I cleaned it up and tested it quite >> thoroughly, our own app as all of the test cases seem to work >> flawlessly with it. It seems that I've broken not too much... :-) >> >> have fun, >> >> Patric >> >> >> >> ______________________________________________________________________ >> >> ---------------------------(end of broadcast)--------------------------- >> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org >-- >Dave Cramer <Dave@micro-automation.net> > > >---------------------------(end of broadcast)--------------------------- >TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) > >
"Patric Bechtel" <bechtel@ipcon.de> writes: > On 03 Jan 2003 09:30:18 -0500, Dave Cramer wrote: > > Dave, > > that's what the useServerPrepare URL property is for. Anyone not > liking (or sort of...) the behaviour of the driver can alter it > so that prepared statements NEVER get prepared on the server. I would prefer ps's to be prepared on the server... that way there is some reliable type checking going on (see the archives of this list for the discussion about security issues and type checking with ps's). Nic
Patric probably thinks that the purpose of the designers of the JDBC API to include the PreparedStatement type into the API was to address the need for (the) "inherent behaviour" and not to spare lazy coders writing a few more lines of code. :))))
Peter
> -----Original Message-----
> From: Dave Cramer [mailto:Dave@micro-automation.net]
> Sent: Friday, January 03, 2003 3:30 PM
> To: Patric Bechtel
> Cc: pgsql-jdbc@postgresql.org
> Subject: Re: [JDBC] Patch for streaming resultsets
>
>
> Patric,
>
> Can you clarify why you want the default behaviour to use server
> prepared statements?
>
> I use prepared statements just because they are easier, not because of
> any inherent behaviour.
>
>
> Dave
>
> On Thu, 2003-01-02 at 11:33, Patric Bechtel wrote:
> > Hello folks,
> >
> > I've made a patch against the current CVS version of the
> JDBC driver,
> > which, based upon Nick Ferrier's patch (thanks!), which adds
> > streaming result sets to the driver.
> > I've made some modifications to the build file, too, as in it's
> > current version it's not able to build clean for JDBC3. I think
> > I fixed that.
> > Another thing I added are three properties which can be included
> > inside the URL:
> >
> > defaultFetchSize=<int>
> >
> > sets the fetch size default to <int>.
> >
> > forceFetchSize=<boolean>
> >
> > in case this property is true, the driver ignores all setFetchSize()
> > API calls from the application. It can be used to get apps, which
> > "know" the postgres driver, work though... :-)
> >
> > useServerPrepare=<never|always>
> >
> > This on alters the behaviour of server prepared statements. The
> > default behaviour is that PreparedStatement's DO get prepared
> > on server side, and normal Statement's do NOT.
> > Setting this property to "never" switches server side preparation
> > off completely, whereas setting it to always even makes
> > normal Statements prepared ones (which can be nice in case of
> > ever and ever repeated queries such as queue lookups).
> >
> > Please note that some parts of the source are commented out
> > for now, as I did not find a way to accomplish the declaration
> > of a cursor for a prepared statement. As for now, this seems
> > to be a feature in upcoming 7.3.2/7.4. But as soon as one of
> > these arrive, we just twig out these comments and there we go...
> >
> > The patch is, as mentioned above, against the most actual CVS
> > version. A single file, PGResultSet.java, belongs into the
> > org/postgresql directory; it needs to be added to the
> > repository.
> >
> > Again, a big thank you for Nick Ferrier, as he made the first
> > version of this; I cleaned it up and tested it quite
> > thoroughly, our own app as all of the test cases seem to work
> > flawlessly with it. It seems that I've broken not too much... :-)
> >
> > have fun,
> >
> > Patric
> >
> >
> >
> >
> ______________________________________________________________________
> >
> > ---------------------------(end of
> broadcast)---------------------------
> > TIP 1: subscribe and unsubscribe commands go to
> majordomo@postgresql.org
> --
> Dave Cramer <Dave@micro-automation.net>
>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to
> majordomo@postgresql.org)
>