Re: PATCH: Add REINDEX tag to event triggers

On Fri, Oct 27, 2023 at 3:15 PM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Mon, Sep 04, 2023 at 08:00:52PM +0200, Jim Jones wrote:
> > LGTM. It applies and builds cleanly, all tests pass and documentation also
> > builds ok. The CFbot seems also much happier now :)
>
> +       /*
> +        * Open and lock the relation.  ShareLock is sufficient since we only need
> +        * to prevent schema and data changes in it.  The lock level used here
> +        * should match catalog's reindex_relation().
> +        */
> +       rel = try_table_open(relid, ShareLock);
>
> I was eyeing at 0003, and this strikes me as incorrect.  Sure, this
> matches what reindex_relation() does, but you've missed that
> CONCURRENTLY takes a lighter ShareUpdateExclusiveLock, and ShareLock
> conflicts with it.  See:
> https://www.postgresql.org/docs/devel/explicit-locking.html
>
> So, doesn't this disrupt a concurrent REINDEX?
> --
> Michael

ReindexPartitions called ReindexMultipleInternal
ReindexRelationConcurrently add reindex_event_trigger_collect to cover
it. (line 3869)
ReindexIndex has the function reindex_event_trigger_collect. (line 2853)

reindex_event_trigger_collect_relation called in
ReindexMultipleInternal, ReindexTable (line 2979).
Both are "under concurrent is false" branches.

So it should be fine.