database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-26 01:22:12 +03:00
Code Activity

Expose some information about backend subxact status.

Browse Source 
A new function pg_stat_get_backend_subxact() can be used to get
information about the number of subtransactions in the cache of
a particular backend and whether that cache has overflowed. This
can be useful for tracking down performance problems that can
result from overflowed snapshots.

Dilip Kumar, reviewed by Zhihong Yu, Nikolay Samokhvalov,
Justin Pryzby, Nathan Bossart, Ashutosh Sharma, Julien
Rouhaud. Additional design comments from Andres Freund,
Tom Lane, Bruce Momjian, and David G. Johnston.

Discussion: http://postgr.es/m/CAFiTN-ut0uwkRJDQJeDPXpVyTWD46m3gt3JDToE02hTfONEN=Q@mail.gmail.com
This commit is contained in:
Robert Haas
2022-12-19 14:43:09 -05:00
parent 7122f9d543
commit 10ea0f924a
8 changed files with 90 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
src/backend/utils/adt/pgstatfuncs.c
View File

@ -687,6 +687,44 @@ pg_stat_get_backend_userid(PG_FUNCTION_ARGS)
PG_RETURN_OID(beentry->st_userid);
}
Datum
pg_stat_get_backend_subxact(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_SUBXACT_COLS 2
TupleDesc tupdesc;
Datum values[PG_STAT_GET_SUBXACT_COLS];
bool nulls[PG_STAT_GET_SUBXACT_COLS];
int32 beid = PG_GETARG_INT32(0);
LocalPgBackendStatus *local_beentry;
/* Initialise values and NULL flags arrays */
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
/* Initialise attributes information in the tuple descriptor */
tupdesc = CreateTemplateTupleDesc(PG_STAT_GET_SUBXACT_COLS);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "subxact_count",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "subxact_overflow",
BOOLOID, -1, 0);
BlessTupleDesc(tupdesc);
if ((local_beentry = pgstat_fetch_stat_local_beentry(beid)) != NULL)
{
/* Fill values and NULLs */
values[0] = Int32GetDatum(local_beentry->backend_subxact_count);
values[1] = BoolGetDatum(local_beentry->backend_subxact_overflowed);
}
else
{
nulls[0] = true;
nulls[1] = true;
}
/* Returns the record as Datum */
PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
}
Datum
pg_stat_get_backend_activity(PG_FUNCTION_ARGS)