Re: pooled prepared statements

From: Thomas Finneid <tfinneid(at)fcon(dot)no>
To: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: pooled prepared statements
Date: 2009-05-12 18:50:14
Message-ID: 4A09C4E6.3010408@fcon.no
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Probably easier to create a server side function instead, then.

regards

thomas

John Lister wrote:
> Thomas Finneid wrote:
>> When a PreparedStatment is created by a pooled connection, as far as I
>> understand if, that creation happens on the server side, and a
>> reference, of sorts, is returned to the client jdbc.
>>
>> Is that prepared statement shared among the connections or is it only
>> available to that single connection? and more importantly, can many
>> connections use that prepared statement concurrently?
>>
>> If it is shared, then it must be usable by concurrent connections,
>> otherwise it will be difficult for the client to know if the statement
>> is occupied or not. So I just want to confirm that I understand how
>> the JDBC driver works.
> Once the query usage count exceeds the prepareThreshold parameter, then
> the driver does create a "prepare statement object" on the server. This
> is only valid for the time the PreparedStatement is open and only on
> that connection. So to answer your question, they cannot be shared by
> multiple connections.
>
> You can create your own using the PREPARE and EXECUTE sql commands so
> long as you track them across different connections...
>
> I'll admit this would be a nice feature for things like JPA where you
> end up creating lots of preparedStatements on different connections,
> reusing or caching a single one may be a worthwhile performance
> optimisation - although not sure about how you would implement it nicely..
>
> JOHN
>

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