From: | Richard Guo <guofenglinux(at)gmail(dot)com> |
---|---|
To: | Miroslav Bendik <miroslav(dot)bendik(at)gmail(dot)com> |
Cc: | David Rowley <dgrowleyml(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Incremental sort for access method with ordered scan support (amcanorderbyop) |
Date: | 2023-06-25 08:18:33 |
Message-ID: | CAMbWs485qtMApvWmO5brUmPHM1yx0z=zZUPGob6PkVpLu861Dw@mail.gmail.com |
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On Thu, Apr 20, 2023 at 9:37 PM Miroslav Bendik <miroslav(dot)bendik(at)gmail(dot)com>
wrote:
> Thanks for this fix. Now the version
> am_orderbyop_incremental_sort_v3.1.patch [1] works without issues
> using the master branch.
The v3.1 patch looks good to me, except that the comments around
match_pathkeys_to_index still need some polish.
1. For comment "On success, the result list is ordered by pathkeys.", I
think it'd be more accurate if we say something like "On success, the
result list is ordered by pathkeys or a prefix list of pathkeys."
considering the possibility of incremental sort.
2. The comment below is not true anymore.
/*
* Note: for any failure to match, we just return NIL immediately.
* There is no value in matching just some of the pathkeys.
*/
We should either remove it or change it to emphasize that we may return
a prefix of the pathkeys for incremental sort.
BTW, would you please add the patch to the CF to not lose track of it?
Thanks
Richard
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