Re: Prepared statements and suboptimal plans - Mailing list pgsql-performance

From Craig Ringer
Subject Re: Prepared statements and suboptimal plans
Date
Msg-id 4E792417.5080205@ringerc.id.au
Whole thread Raw
In response to Prepared statements and suboptimal plans  (Royce Ausburn <royce.ml@inomial.com>)
Responses Re: Prepared statements and suboptimal plans  (Royce Ausburn <royce.ml@inomial.com>)
Re: Prepared statements and suboptimal plans  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
On 21/09/2011 7:27 AM, Royce Ausburn wrote:
> Hi all,
>
> It looks like I've been hit with this well known issue.  I have
> a complicated query that is intended to run every few minutes, I'm
> using JDBC's Connection.prepareStatement() mostly for nice
> parameterisation, but postgres produces a suboptimal plan due to its
> lack of information when the statement is prepared.
>
> [snip]
>
> We've been worst hit by this query on an 8.3 site.  Another site is
> running 8.4.  Have there been improvements in this area recently?
>  Upgrading to 9.0 might be viable for us.

Tom just mentioned that 9.1 will be able to re-plan parameterized
prepared statements, so this issue will go away. In the mean time you
can only really use the standard workaround of setting the prepare
theshold to 0 to disable server-side prepare, so you can continue to use
JDBC prepared statements and have the driver do the parameter
substitution for you.

--
Craig Ringer

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