"Simon Riggs" <[EMAIL PROTECTED]> writes:
> On Tue, 2007-03-06 at 12:22 -0500, Tom Lane wrote:
>> A. Just accept the extra overhead, thereby preserving the current
>> behavior of unnamed statements, and gaining the benefit that plan
>> invalidation will work correctly in the few cases where an unnamed
>> statement's plan lasts long enough to need replanning.
> With connection pooling, multiple sessions will execute each statement.
> If we check the cache each time this does seem more expensive for each
> individual session, but we should gain synergy from other similar
> sessions.
It seems fairly unlikely to me that client code would try to share an
unnamed statement across multiple application threads; the entire point
is that it's for one-off queries.
Or did you miss the point that the plan cache is local per-backend?
> ISTM there will be some cases where the current behaviour will not be
> maintained if we implement A exactly. One thing I've not seen mentioned
> is the effect of constants on various plans.
There is none.
regards, tom lane
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
