From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Kris Jurka <books(at)ejurka(dot)com> |
Cc: | SZŰCS Gábor <surrano(at)mailbox(dot)hu>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: 7.2.1: coalesce double-calls function? |
Date: | 2003-02-04 18:26:15 |
Message-ID: | 15607.1044383175@sss.pgh.pa.us |
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Lists: | pgsql-general |
Kris Jurka <books(at)ejurka(dot)com> writes:
> I have been looking at this and the NULLIF case seems complicatd.
> Essentially for NULLIF(left,right) I want to ExecEvalExpr(left,...)
> and construct a Const node with the result. Then makeSimpleA_Expr for
> const left = right.
Uh, no; you are confusing parse-time and run-time work. What you
probably want is a new node type that includes the OID of the
appropriate "=" operator but does different things with the result
than a normal "=" invocation would do.
Actually, thinking about it that way, it might just be a small variant
on the DistinctExpr node type that exists in current sources. Certainly
DistinctExpr would be a good model to look at.
regards, tom lane
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