Re: Does PostgreSQL do bind-peeking? Is `col like '%'` optimized-away by the planner? - Mailing list pgsql-general

From Tom Lane
Subject Re: Does PostgreSQL do bind-peeking? Is `col like '%'` optimized-away by the planner?
Date
Msg-id 1191689.1642783673@sss.pgh.pa.us
Whole thread Raw
In response to Does PostgreSQL do bind-peeking? Is `col like '%'` optimized-away by the planner?  (Dominique Devienne <ddevienne@gmail.com>)
Responses Re: Does PostgreSQL do bind-peeking? Is `col like '%'` optimized-away by the planner?
List pgsql-general
Dominique Devienne <ddevienne@gmail.com> writes:
> Will the query planner be able to *peek* into the args, and turn the
> `colN like $N`
> into a no-op?

No.  It would not do that even if the pattern were constant '%';
it doesn't know that much about that particular function.

There is a notion of "custom plans" in which parameter values are
inserted as constants, precisely to allow simplifications based on
known constant values.  But this particular case isn't implemented.

I am entirely unfamiliar with the terminology "bind-peeking", so
I can't say whether that's effectively the same thing as our
custom plans.

            regards, tom lane



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