Horton

Re: Showing primitive index scan count in EXPLAIN ANALYZE (for skip scan and SAOP scans)

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-08-27T19:04:15Z
Lists: pgsql-hackers 
Peter Geoghegan <pg@bowt.ie> writes:
> I see value in making it obvious to users when and how
> pg_stat_all_indexes.idx_scan advances. Being able to easily relate it
> to EXPLAIN ANALYZE output is useful, independent of whether or not
> SAOPs happen to be used. That's probably the single best argument in
> favor of showing "Index Searches: N" unconditionally. But I'm
> certainly not going to refuse to budge over that.

TBH, I'm afraid that this patch basically is exposing numbers that
nobody but Peter Geoghegan and maybe two or three other hackers
will understand, and even fewer people will find useful (since the
how-many-primitive-scans behavior is not something users have any
control over, IIUC).  I doubt that "it lines up with
pg_stat_all_indexes.idx_scan" is enough to justify the additional
clutter in EXPLAIN.  Maybe we should be going the other direction
and trying to make pg_stat_all_indexes count in a less detailed but
less surprising way, ie once per indexscan plan node invocation.

			regards, tom lane

Commits

  1. Show index search count in EXPLAIN ANALYZE, take 2.

  2. Show index search count in EXPLAIN ANALYZE.

  3. Allow usage of match_orclause_to_indexcol() for joins

  4. Fix nbtree pgstats accounting with parallel scans.

  5. Enhance nbtree ScalarArrayOp execution.

  6. Fix EXPLAIN ANALYZE of hash join when the leader doesn't participate.