| From: | Andrzej Barszcz <abusinf(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: function calls optimization |
| Date: | 2019-10-31 15:51:11 |
| Message-ID: | CAOUVqAzrk2KoWucrKJ5AUest2JdYrvM2qaR93QWB+COAH2EWYg@mail.gmail.com |
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| Lists: | pgsql-hackers |
x <> 0 is evaluated first, 1/x only when x <> 0, not ?
czw., 31 paź 2019 o 16:45 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napisał(a):
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > Potentially related note: for nodes like seqscan, combining the qual and
> projection processing into one expression seems to be a noticable win (at
> least when taking care do emit two different sets of deform expression
> steps).
>
> There's just one problem: that violates SQL semantics, and not in
> a small way.
>
> select 1/x from tab where x <> 0
>
> regards, tom lane
>
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