From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, benoit <benoit(at)hopsandfork(dot)com>, Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
Subject: | Re: Optimizing nbtree ScalarArrayOp execution, allowing multi-column ordered scans, skip scan |
Date: | 2024-04-08 01:36:17 |
Message-ID: | CAH2-Wz=BH6SnWAM3b70sJ-CsxTcFR_VxHxDzNag=1N4eWs3K5w@mail.gmail.com |
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On Sun, Apr 7, 2024 at 9:25 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Perhaps this'd help:
>
> - Assert(xform[j].ikey == array->scan_key);
> + Assert(array && xform[j].ikey == array->scan_key);
>
> If that doesn't silence it, I'd be prepared to just dismiss the
> warning.
The assertions in question are arguably redundant. There are very
similar assertions just a little earlier on, as we initially set up
the array stuff (right before _bt_compare_scankey_args is called).
I'll just remove the "Assert(xform[j].ikey == array->scan_key)"
assertion that Coverity doesn't like, in addition to the
"Assert(!array || array->scan_key == i)" assertion, on the grounds
that they're redundant.
> Some work in the comment to explain why we must have an array here
> wouldn't be out of place either, perhaps.
There is a comment block about this right above the assertion in question:
/*
* Both scan keys might have arrays, in which case we'll
* arbitrarily pass only one of the arrays. That won't
* matter, since _bt_compare_scankey_args is aware that two
* SEARCHARRAY scan keys mean that _bt_preprocess_array_keys
* failed to eliminate redundant arrays through array merging.
* _bt_compare_scankey_args just returns false when it sees
* this; it won't even try to examine either array.
*/
Do you think it needs more work?
--
Peter Geoghegan
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