Joachim Wieland <joe@mcknight.de> writes:
> So irrespective of caching to prevent evaluation across statements, within a
> single statement, is there a strong reason why for example in
> WHERE col = f(const) with f() declared as immutable or stable and without an
> index on col, f() still gets called for every row? Or is this optimization
> just not done yet?

The above statement is not correct, at least not for immutable functions.

regards, tom lane

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