Re: Patch for streaming resultsets [Viruschecked]

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
>>
>>
>>
>> ______________________________________________________________________
>>
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>--
>Dave Cramer <Dave@micro-automation.net>
>
>
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