Re: ExecRTCheckPerms() and many prunable partitions

From: Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>
To: Amit Langote <amitlangote09(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: David Rowley <dgrowleyml(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Zhihong Yu <zyu(at)yugabyte(dot)com>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: ExecRTCheckPerms() and many prunable partitions
Date: 2022-10-12 13:49:56
Message-ID: 94353655-c177-1f55-7afb-b2090de33341@enterprisedb.com
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On 06.10.22 15:29, Amit Langote wrote:
> I tried in the attached 0004. ModifyTable gets a new member
> extraUpdatedColsBitmaps, which is List of Bitmapset "nodes".
>
> Actually, List of Bitmapsets turned out to be something that doesn't
> just-work with our Node infrastructure, which I found out thanks to
> -DWRITE_READ_PARSE_PLAN_TREES. So, I had to go ahead and add
> first-class support for copy/equal/write/read support for Bitmapsets,
> such that writeNode() can write appropriately labeled versions of them
> and nodeRead() can read them as Bitmapsets. That's done in 0003. I
> didn't actually go ahead and make*all* Bitmapsets in the plan trees
> to be Nodes, but maybe 0003 can be expanded to do that. We won't need
> to make gen_node_support.pl emit *_BITMAPSET_FIELD() blurbs then; can
> just use *_NODE_FIELD().

Seeing that on 64-bit platforms we have a 4-byte padding gap in the
Bitmapset struct, sticking a node tag in there seems pretty sensible.
So turning Bitmapset into a proper Node and then making the other
adjustments you describe makes sense to me.

Making a new thread about this might be best.

(I can't currently comment on the rest of the patch set. So I don't
know if you'll really end up needing lists of bitmapsets. But from here
it looks like turning bitmapsets into nodes might be a worthwhile change
just by itself.)

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