Hi,
This is a proposal of a patch for pg_stat_statements extension. It
corrects deallocation events accounting.
Since 2e0fedf there is a view pg_stat_statements_info is available in
pg_stat_statements extension. It has a dealloc field, that should be a
counter of deallocation events happened.
Right now it accounts only automatic deallocation events, happened when
we need a place for a new statement, but manual deallocation events
caused by pg_stat_statements_reset() function for some subset of
collected statements is not accounted.
My opinion is that manual deallocation is a deallocation too and it
must be accounted in dealloc field of pg_stat_statements_info view.
Let's see how it happens:
postgres=# select pg_stat_statements_reset();
postgres=# select 1;
?column?
----------
1
(1 row)
postgres=# select dealloc from pg_stat_statements_info ;
dealloc
---------
0
(1 row)
postgres=# select pg_stat_statements_reset(userid,dbid,queryid)
postgres-# from pg_stat_statements where query = 'select $1';
pg_stat_statements_reset
--------------------------
(1 row)
postgres=# select dealloc from pg_stat_statements_info ;
dealloc
---------
0 -- Here must be a one now, as deallocation happened
(1 row)
This patch adds accounting of manual deallocation events.
--
Andrei Zubkov
Postgres Professional
The Russian Postgres Company
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 62cccbfa44..184e5c08ea 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -2579,7 +2579,18 @@ entry_reset(Oid userid, Oid dbid, uint64 queryid)
/* All entries are removed? */
if (num_entries != num_remove)
+ {
+ if (num_remove)
+ {
+ /* Increment the number of times entries are deallocated */
+ volatile pgssSharedState *s = (volatile pgssSharedState *) pgss;
+
+ SpinLockAcquire(&s->mutex);
+ s->stats.dealloc += 1;
+ SpinLockRelease(&s->mutex);
+ }
goto release_lock;
+ }
/*
* Reset global statistics for pg_stat_statements since all entries are
