Message-ID: <c2619b41-37da-4fed-99db-1444072771bd@vondra.me>
Date: Thu, 22 May 2025 15:04:45 +0200
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Subject: Re: generic plans and "initial" pruning
To: Amit Langote <amitlangote09@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Tender Wang <tndrwang@gmail.com>, Alexander Lakhin <exclusion@gmail.com>,
 Robert Haas <robertmhaas@gmail.com>, Alvaro Herrera
 <alvherre@alvh.no-ip.org>, Andres Freund <andres@anarazel.de>,
 Daniel Gustafsson <daniel@yesql.se>, David Rowley <dgrowleyml@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>,
 Thom Brown <thom@linux.com>
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From: Tomas Vondra <tomas@vondra.me>
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On 5/22/25 10:12, Amit Langote wrote:
> On Wed, May 21, 2025 at 7:22 PM Amit Langote <amitlangote09@gmail.com> wrote:
>> Fair enough. I’ll revert this and some related changes shortly.  WIP
>> patch attached.
> 
> I have pushed out the revert now.
> 

Thank you.

> Note that I’ve only reverted the changes related to deferring locks on
> prunable partitions. I’m planning to leave the preparatory commits
> leading up to that one in place unless anyone objects. For reference,
> here they are in chronological order (the last 3 are bug fixes):
> 
> bb3ec16e14d Move PartitionPruneInfo out of plan nodes into PlannedStmt
> d47cbf474ec Perform runtime initial pruning outside ExecInitNode()
> cbc127917e0 Track unpruned relids to avoid processing pruned relations
> 75dfde13639 Fix an oversight in cbc127917 to handle MERGE correctly
> cbb9086c9ef Fix bug in cbc127917 to handle nested Append correctly
> 28317de723b Ensure first ModifyTable rel initialized if all are pruned
> 
> I think separating initial pruning from plan node initialization is
> still worthwhile on its own, as evidenced by the improvements in
> cbc127917e.
> 

I'm OK with that in principle, assuming the benefits outweigh the risk
of making backpatching harder. The patches don't seem exceptionally
large / invasive, but I don't know how often we modify these parts.


regards

-- 
Tomas Vondra