From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
Cc: | Amit Langote <amitlangote09(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> |
Subject: | Making Bitmapsets be valid Nodes |
Date: | 2022-11-11 20:05:58 |
Message-ID: | 109089.1668197158@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Per the discussion at [1], it seems like it'd be a good idea to make
Bitmapsets into full-fledged, tagged Nodes, so that we could do things
like print or copy lists of them without special-case logic. The
extra space for the NodeTag is basically free due to alignment
considerations, at least on 64-bit hardware.
Attached is a cleaned-up version of Amit's patch v24-0003 at [2].
I fixed the problems with not always tagging Bitmapsets, and changed
the outfuncs/readfuncs logic so that Bitmapsets still print exactly
as they did before (thus, this doesn't require a catversion bump).
As proof of concept, I removed the read_write_ignore labels from
RelOptInfo's unique_for_rels and non_unique_for_rels fields, and
got nice-looking debug printout:
:unique_for_rels ((b 1))
:non_unique_for_rels <>
I also removed some special-case code from indxpath.c because
list_member() can do the same thing now. (There might be other
places that can be simplified; I didn't look very hard.)
It'd be possible to make Bitmapset fields be (mostly) not special cases
in the copy/equal/out/read support. But I chose to leave that alone,
because it'd add a little runtime overhead for indirecting through the
generic support functions while not really saving any code space.
Barring objections, I'd like to go ahead and push this.
regards, tom lane
[1] https://www.postgresql.org/message-id/94353655-c177-1f55-7afb-b2090de33341%40enterprisedb.com
[2] https://www.postgresql.org/message-id/CA%2BHiwqEYCLRZ2Boq_uK0pjLn_9b8XL-LmwKj7HN5kJOivUkYLg%40mail.gmail.com
Attachment | Content-Type | Size |
---|---|---|
v1-0001-make-Bitmapsets-be-valid-Nodes.patch | text/x-diff | 10.0 KB |
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