Re: Revert: Remove useless self-joins *and* -DREALLOCATE_BITMAPSETS make server crash, regress test fail. - Mailing list pgsql-hackers

From David Rowley
Subject Re: Revert: Remove useless self-joins *and* -DREALLOCATE_BITMAPSETS make server crash, regress test fail.
Date
Msg-id CAApHDvp5Az4MA3r1REaV=NyTF=30qNhe+N=OWb5g_edAvS+rCA@mail.gmail.com
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In response to Re: Revert: Remove useless self-joins *and* -DREALLOCATE_BITMAPSETS make server crash, regress test fail.  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Revert: Remove useless self-joins *and* -DREALLOCATE_BITMAPSETS make server crash, regress test fail.  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Thu, 9 May 2024 at 06:24, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I like alternative-2.patch a lot better, not least because it
> only adds cycles when join removal actually fires.  Basically
> this is putting the onus on the data structure modifier to
> cope with shared bitmapsets, rather than trying to say that
> sharing is disallowed.
>
> Thoughts?

I'm fine with this one as it's the same as what I already mentioned
earlier.  I had imagined doing bms_del_member(bms_copy ... but maybe
the compiler is able to optimise away the additional store. Likely, it
does not matter much as pallocing memory likely adds far more overhead
anyway.

David



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