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Re: statement caching proof of concept

From: Dave Cramer <pg(at)fastcrypt(dot)com>
To: Oliver Jowett <oliver(at)opencloud(dot)com>
Cc: List <pgsql-jdbc(at)postgresql(dot)org>
Subject: Re: statement caching proof of concept
Date: 2006-06-19 23:34:14
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-jdbc
On 19-Jun-06, at 7:15 PM, Oliver Jowett wrote:

> Dave Cramer wrote:
>> This is just proof of concept. More work has to be done to make it  
>> build properly and work properly under different jdk's
> Isn't there a bunch of statement state (things like fetch size, max  
> rows, etc) that have defined defaults and this cache implementation  
> will not provide?

Good point, these would all have to be reset to their defaults as well.

> The "wrapper" implementation approach suffers from the usual  
> difficulty that the "back links" such as ResultSet.getStatement()  
> point to the wrong object. It's actually quite a bit of work to get  
> this right..
Since result sets only live as long as the statement, wouldn't they  
point to the statement that is still open ?
> The cached statements are vulnerable to buggy apps that mutate the  
> statement after close, since there's no interception of those  
> methods to check whether the wrapper statement has been closed.

No question, and I would certainly not make this the default  
behaviour. The user would have to turn on caching.
> What exactly is the performance bottleneck you're trying to avoid  
> by having the statement pool? If it's the parse/plan cost, I think  
> Mark's suggestion of putting the cache at the protocol level may be  
> simpler. If it's overall statement cost, you might be better off  
> with a generic wrapper that is not postgresql-specific at all.

How does the generic wrapper solve the problems above ? I would think  
they all suffer from the same problems ?
> -O

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