Re: Switching to 64-bit Bitmapsets
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-12-20T04:50:24Z
Lists: pgsql-hackers
David Rowley <david.rowley@2ndquadrant.com> writes: > I've attached the trivial patch which implements 64-bit Bitmapsets. > One caveat about this may be that it will likely slow performance for > 32-bit machines. My current thinking about that is that such a > platform is likely not that common a target for the latest version of > PostgreSQL. Yeah, I think we've been optimizing for 64-bit platforms for awhile. I'm not prepared to abandon "it works on 32-bit", but I don't see a reason to sacrifice 64-bit performance to improve the 32-bit case. > However, I doubt it would take much more effort to maintain > using 32-bit sets on 32-bit machines. If someone feels strongly about > that then I can adjust the patch to allow that. Hm, are you thinking of making BITS_PER_BITMAPWORD match sizeof(Pointer) or something like that? That seems like a good compromise from here. regards, tom lane
Commits
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Make bitmapset.c use 64-bit bitmap words on 64-bit machines.
- 216af5eea5c8 12.0 landed