Tom Lane wrote:
"Florian G. Pflug" <[EMAIL PROTECTED]> writes:
Tom Lane wrote:
But you don't have any cost numbers until after you've done the plan.

Couldn't this work similar to geqo_effort? The planner could
try planning the query using only cheap algorithmns, and if
the cost exceeds a certain value, it'd restart, and use
more sophisticated methods.

AFAICS this would be a net loss on average.  Most of the time, the
constraint exclusion code doesn't win, and so throwing away all your
planning work to try it is going to be a loser most of the time.

On the other hand, if the "consider-replanning" threshold is high enough,
than that additional time really doesn't matter - If a query runs for minutes,
or even hours, a few wasted cycles during planning don't hurt.

greetings, Florian Pflug

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