Don't build extended statistics on inheritance trees
When performing ANALYZE on inheritance trees, we collect two samples for
each relation - one for the relation alone, and one for the inheritance
subtree (relation and its child relations). And then we build statistics
on each sample, so for each relation we get two sets of statistics.
For regular (per-column) statistics this works fine, because the catalog
includes a flag differentiating statistics built from those two samples.
But we don't have such flag in the extended statistics catalogs, and we
ended up updating the same row twice, triggering this error:
ERROR: tuple already updated by self
The simplest solution is to disable extended statistics on inheritance
trees, which is what this commit is doing. In the future we may need to
do something similar to per-column statistics, but that requires adding a
flag to the catalog - and that's not backpatchable. Moreover, the current
selectivity estimation code only works with individual relations, so
building statistics on inheritance trees would be pointless anyway.
Author: Tomas Vondra
Backpatch-to: 10-
Discussion: https://postgr.es/m/20190618231233.GA27470@telsasoft.com
Reported-by: Justin Pryzby
Branch
------
REL_11_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/4dbf70b2ff1ee487923394fd9e4fb28bb78839f2
Modified Files
--------------
src/backend/commands/analyze.c | 12 +++++++++---
src/test/regress/expected/stats_ext.out | 8 ++++++++
src/test/regress/sql/stats_ext.sql | 8 ++++++++
3 files changed, 25 insertions(+), 3 deletions(-)
