Add system view pg_stat_recovery This commit introduces pg_stat_recovery, that exposes at SQL level the state of recovery as tracked by XLogRecoveryCtlData in shared memory, maintained by the startup process. This new view includes the following fields, that are useful for monitoring purposes on a standby, once it has reached a consistent state (making the execution of the SQL function possible): - Last-successfully replayed WAL record LSN boundaries and its timeline. - Currently replaying WAL record end LSN and its timeline. - Current WAL chunk start time. - Promotion trigger state. - Timestamp of latest processed commit/abort. - Recovery pause state.
Some of this data can already be recovered from different system functions, but not all of it. See pg_get_wal_replay_pause_state or pg_last_xact_replay_timestamp. This new view offers a stronger consistency guarantee, by grabbing the recovery state for all fields through one spinlock acquisition. The system view relies on a new function, called pg_stat_get_recovery(). Querying this data requires the pg_read_all_stats privilege. The view returns no rows if the node is not in recovery. This feature originates from a suggestion I have made while discussion the addition of a CONNECTING state to the WAL receiver's shared memory state, because we lacked access to some of the state data. The author has taken the time to implement it, so thanks for that. Bump catalog version. Author: Xuneng Zhou <[email protected]> Discussion: https://postgr.es/m/cabptf7w+nody-+p9y4pnk37-qwulpfureonhuehrx+vx9kq...@mail.gmail.com Discussion: https://postgr.es/m/[email protected] Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/01d485b142e4c89aef79da9fd60f203c1bd4458b Modified Files -------------- doc/src/sgml/monitoring.sgml | 151 +++++++++++++++++++++++++++++++++ src/backend/access/transam/xlogfuncs.c | 94 ++++++++++++++++++++ src/backend/catalog/system_views.sql | 14 +++ src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.dat | 7 ++ src/test/recovery/t/001_stream_rep.pl | 5 ++ src/test/regress/expected/rules.out | 11 +++ src/test/regress/expected/sysviews.out | 7 ++ src/test/regress/sql/sysviews.sql | 3 + 9 files changed, 293 insertions(+), 1 deletion(-)
