Re: ANALYZE: ERROR: tuple already updated by self

Hi,

On 2019-06-18 18:48:58 -0500, Justin Pryzby wrote:
> Ah: the table is an inheritence parent.  If I uninherit its child, there's no
> error during ANALYZE.  MV stats on the child are ok:

It's a "classical" inheritance parent, not a builtin-partitioning type
of parent, right? And it contains data?

I assume it ought to not be too hard to come up with a reproducer
then...

I think the problem is pretty plainly that for inheritance tables we'll
try to store extended statistics twice. And thus end up updating the
same row twice.

> #6  0x0000000000588346 in do_analyze_rel (onerel=0x7fee16140de8, options=2, params=0x7ffe5b6bf8b0, va_cols=0x0, acquirefunc=0x492b4, relpages=36, inh=true, in_outer_xact=false, elevel=13) at analyze.c:627

		/* Build extended statistics (if there are any). */
		BuildRelationExtStatistics(onerel, totalrows, numrows, rows, attr_cnt,
								   vacattrstats);

Note that for plain statistics we a) pass down the 'inh' flag to the
storage function, b) stainherit is part of pg_statistics' key:

Indexes:
    "pg_statistic_relid_att_inh_index" UNIQUE, btree (starelid, staattnum, stainherit)


Tomas, I think at the very least extended statistics shouldn't be built
when building inherited stats. But going forward I think we should
probably have it as part of the key for pg_statistic_ext.

Greetings,

Andres Freund