Re: Delaying the planning of unnamed statements until Bind

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Oliver Jowett <oliver(at)opencloud(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Delaying the planning of unnamed statements until Bind
Date: 2004-05-22 01:55:12
Message-ID: 3687.1085190912@sss.pgh.pa.us
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Oliver Jowett <oliver(at)opencloud(dot)com> writes:
> Ok, so something like this?
> 1) eval_const_expressions takes a list of parameter values and does
> Param to Const replacement if given parameters.
> 2) The main planner does not pass parameters to eval_const_expressions.
> 3) When the selectivity functions care about a Const vs non-Const value
> and they are dealing with a non-leaf expression node, they call
> eval_const_expressions passing the expression tree & the planner-global
> parameter values, and then look at the result's Const-ness again.

Right.

> There appear to be a few other places where Const vs. Param affects the
> resulting plan (clause_selectivity, LIMIT/OFFSET support, etc). Do the
> same thing there?

clause_selectivity could reasonably do this. Not sure about
LIMIT/OFFSET.

regards, tom lane

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