postgresql/src/backend/utils
Fujii Masao 3b733fcd04 Display the time when the process started waiting for the lock, in pg_locks.
This commit adds new column "waitstart" into pg_locks view. This column
reports the time when the server process started waiting for the lock
if the lock is not held. This information is useful, for example, when
examining the amount of time to wait on a lock by subtracting
"waitstart" in pg_locks from the current time, and identify the lock
that the processes are waiting for very long.

This feature uses the current time obtained for the deadlock timeout
timer as "waitstart" (i.e., the time when this process started waiting
for the lock). Since getting the current time newly can cause overhead,
we reuse the already-obtained time to avoid that overhead.

Note that "waitstart" is updated without holding the lock table's
partition lock, to avoid the overhead by additional lock acquisition.
This can cause "waitstart" in pg_locks to become NULL for a very short
period of time after the wait started even though "granted" is false.
This is OK in practice because we can assume that users are likely to
look at "waitstart" when waiting for the lock for a long time.

Bump catalog version.

Author: Atsushi Torikoshi
Reviewed-by: Ian Lawrence Barwick, Robert Haas, Justin Pryzby, Fujii Masao
Discussion: https://postgr.es/m/a96013dc51cdc56b2a2b84fa8a16a993@oss.nttdata.com
2021-02-09 18:10:19 +09:00
..
adt Display the time when the process started waiting for the lock, in pg_locks. 2021-02-09 18:10:19 +09:00
cache Improve performance of repeated CALLs within plpgsql procedures. 2021-01-25 22:28:29 -05:00
error Add pg_stat_database counters for sessions and session time 2021-01-17 13:52:31 +01:00
fmgr Fix broken ruleutils support for function TRANSFORM clauses. 2021-01-25 13:03:43 -05:00
hash Update copyright for 2021 2021-01-02 13:06:25 -05:00
init Reduce the default value of vacuum_cost_page_miss. 2021-01-27 15:11:13 -08:00
mb Add direct conversion routines between EUC_TW and Big5. 2021-01-28 14:53:03 +02:00
misc Reduce the default value of vacuum_cost_page_miss. 2021-01-27 15:11:13 -08:00
mmgr Improve performance of repeated CALLs within plpgsql procedures. 2021-01-25 22:28:29 -05:00
resowner Improve performance of repeated CALLs within plpgsql procedures. 2021-01-25 22:28:29 -05:00
sort Update copyright for 2021 2021-01-02 13:06:25 -05:00
time Revive "snapshot too old" with wal_level=minimal and SET TABLESPACE. 2021-01-30 00:12:18 -08:00
.gitignore Rearrange makefile rules for running Gen_fmgrtab.pl. 2018-05-03 17:54:18 -04:00
errcodes.txt Rethink SQLSTATE code for ERRCODE_IDLE_SESSION_TIMEOUT. 2021-01-11 14:53:42 -05:00
Gen_dummy_probes.pl Update copyright for 2021 2021-01-02 13:06:25 -05:00
Gen_dummy_probes.sed Update copyright for 2021 2021-01-02 13:06:25 -05:00
Gen_fmgrtab.pl Update copyright for 2021 2021-01-02 13:06:25 -05:00
generate-errcodes.pl Update copyright for 2021 2021-01-02 13:06:25 -05:00
Makefile Update copyright for 2021 2021-01-02 13:06:25 -05:00
probes.d Update copyright for 2021 2021-01-02 13:06:25 -05:00