From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
cc: exclusion@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18499: Reindexing spgist index concurrently triggers
 Assert("TransactionIdIsValid(state->myXid)")
In-reply-to: <Zm90GkbGq16gjJy0@paquier.xyz>
References: <18499-8a519c280f956480@postgresql.org>
 <428421.1717887173@sss.pgh.pa.us> <3030961.1718570047@sss.pgh.pa.us>
 <3045795.1718578372@sss.pgh.pa.us> <Zm90GkbGq16gjJy0@paquier.xyz>
Comments: In-reply-to Michael Paquier <michael@paquier.xyz>
	message dated "Mon, 17 Jun 2024 08:24:10 +0900"
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Date: Sun, 16 Jun 2024 19:30:46 -0400
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Michael Paquier <michael@paquier.xyz> writes:
> On Sun, Jun 16, 2024 at 06:52:52PM -0400, Tom Lane wrote:
>> ... not sure there's a nice way for spginsert() to know whether it's
>> being invoked in REINDEX CONCURRENTLY or a normal INSERT/UPDATE
>> query.  Can we trust indexInfo->ii_Concurrent for that?

> I am not sure to understand the redirection part for spgist, but
> except if I am missing something, we already rely on ii_Concurrent for
> other index AMs like BRIN paths to check if we are dealing with a
> concurrent build path or not.  index_concurrently_build() is used
> by both CIC and REINDEX CONCURRENTLY, where the flag is set after a
> BuildIndexInfo().

Right.  I was thinking that CIC wouldn't reach spginsert(), rather
spgbuild(), but it does feel a bit rickety.  A separate flag would
be better.

On the whole I'm inclined to stick with the patch as I have it.
Maybe somebody would like to investigate this idea as an improvement
for v18 or later.

			regards, tom lane