On 2020/11/19 14:33, torikoshia wrote:
On 2020-11-18 11:35, Fujii Masao wrote:
Thanks for your comment!
On 2020/11/18 11:04, torikoshia wrote:
Hi,
AFAIU, when the planner statistics are updated, generic plans are invalidated
and PostgreSQL recreates. However, the manual doesn't seem to explain it
explicitly.
https://www.postgresql.org/docs/devel/sql-prepare.html
I guess this case is included in 'whenever database objects used in the
statement have definitional (DDL) changes undergone', but I feel it's hard to
infer.
Since updates of the statistics can often happen, how about describing this
case explicitly like an attached patch?
+1 to add that note.
- statement. Also, if the value of <xref linkend="guc-search-path"/> changes
+ statement. For example, when the planner statistics of the statement
+ are updated, <productname>PostgreSQL</productname> re-analyzes and
+ re-plans the statement.
I don't think "For example," is necessary.
"planner statistics of the statement" sounds vague? Does the statement
is re-analyzed and re-planned only when the planner statistics of database
objects used in the statement are updated? If yes, we should describe
that to make the note a bit more explicitly?
Yes. As far as I confirmed, updating statistics which are not used in
prepared statements doesn't trigger re-analyze and re-plan.
Since plan invalidations for DDL changes and statistcal changes are caused
by PlanCacheRelCallback(Oid 'relid'), only the prepared statements using
'relid' relation seem invalidated.>
Attached updated patch.
Thanks for confirming that and updating the patch!
Barring any objection, I will commit the patch.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
