Horton

Re: Large expressions in indexes can't be stored (non-TOASTable)

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Alexander Lakhin <exclusion@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, "Jonathan S. Katz" <jkatz@postgresql.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-10-16T01:20:17Z
Lists: pgsql-hackers 
On Wed, Oct 16, 2024 at 09:12:31AM +0900, Michael Paquier wrote:
> -   if (!ctx->rel->rd_rel->reltoastrelid)
> +   if (!OidIsValid(RelationGetToastRelid(ctx->rel)))
> 
> This set of diffs in 0002 is a nice cleanup.  I'd wish for relying
> less on zero comparitons when assuming that InvalidOid is in use.

I'm wondering if there's any concern about this one causing back-patching
pain.  If so, I can just add the macro for use in new code.

> +static inline void
> +AssertHasSnapshotForToast(Relation rel)
> +{
> +	/* bootstrap mode in particular breaks this rule */
> +	if (!IsNormalProcessingMode())
> +		return;
> +
> +	/* if the relation doesn't have a TOAST table, we are good */
> +	if (!OidIsValid(RelationGetToastRelid(rel)))
> +		return;
> +
> +	Assert(HaveRegisteredOrActiveSnapshot());
> +}
> 
> Using a separate inlined routine is indeed cleaner as you have
> documented the assumptions behind the check.  Wouldn't it be better to
> use a USE_ASSERT_CHECKING block?  These two checks for normal
> processing and toastrelid are cheap lookups, but we don't need them at
> all in non-assert paths, so I'd suggest to ignore them entirely for
> the non-USE_ASSERT_CHECKING case.

I assume all of this will get compiled out in non-USE_ASSERT_CHECKING
builds as-is, but I see no problem with surrounding it with an #ifdef to be
sure.

-- 
nathan

Commits

  1. Ensure we have a snapshot when updating various system catalogs.

  2. Remove pg_replication_origin's TOAST table.

  3. Restrict password hash length.

  4. Ensure we have a snapshot when updating pg_index entries.

  5. Add TOAST table to pg_index.

  6. Add toast tables to most system catalogs