Hi, On 2022-10-12 12:50:31 -0700, Andres Freund wrote: > I think this should have at a basic test in src/test/regress/sql/stats.sql. If > I can write one in a few minutes I'll go for that, otherwise will reply > detailing difficulties.
Took a bit longer (+lunch). Attached. In the attached 0001, the patch to make GetCurrentTransactionStopTimestamp() set xactStopTimestamp, I added a few comment updates and an Assert() to ensure that CurrentTransactionState->state is TRANS_(DEFAULT|COMMIT|ABORT|PREPARE). I am worried that otherwise we might end up with someone ending up using it in a place before the end of the transaction, which'd then end up recording the wrong timestamp in the commit/abort record. For 0002, the commit adding lastscan, I added catversion/stats version bumps (because I was planning to commit it already...), a commit message, and that minor docs change mentioned earlier. 0003 adds the tests mentioned above. I plan to merge them with 0002, but left them separate for easier review for now. To be able to compare timestamps for > not just >= we need to make sure that two subsequent timestamps differ. The attached achieves this by sleeping for 100ms between those points - we do that in other places already. I'd started out with 10ms, which I am fairly sure would suffice, but then deciced to copy the existing 100ms sleeps. I verified tests pass under valgrind, debug_discard_caches and after I make pgstat_report_stat() only flush when force is passed in. Greetings, Andres Freund
>From 976679bc590560d3c051e30e7576e7d3d03070e6 Mon Sep 17 00:00:00 2001 From: Andres Freund <and...@anarazel.de> Date: Wed, 12 Oct 2022 14:43:41 -0700 Subject: [PATCH v5 1/3] Have GetCurrentTransactionStopTimestamp() set xactStopTimestamp if unset Previously GetCurrentTransactionStopTimestamp() computed a new timestamp whenever xactStopTimestamp was unset and xactStopTimestamp was only set when a commit or abort record was written. An upcoming patch will add additional calls to GetCurrentTransactionStopTimestamp() from pgstats. To avoid computing timestamps multiple times, set xactStopTimestamp in GetCurrentTransactionStopTimestamp() if not already set. Author: Dave Page <dp...@pgadmin.org> Reviewed-by: Andres Freund <and...@anarazel.de> Reviewed-by: Vik Fearing <v...@postgresfriends.org> Discussion: https://postgr.es/m/20220906155325.an3xesq5o3fq36gt%40awork3.anarazel.de --- src/backend/access/transam/xact.c | 42 +++++++++++++++---------------- 1 file changed, 21 insertions(+), 21 deletions(-) diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index c1ffbd89b88..fd5103a78e2 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -263,7 +263,10 @@ static bool currentCommandIdUsed; /* * xactStartTimestamp is the value of transaction_timestamp(). * stmtStartTimestamp is the value of statement_timestamp(). - * xactStopTimestamp is the time at which we log a commit or abort WAL record. + * xactStopTimestamp is the time at which we log a commit / abort WAL record, + * or if that was skipped, the time of the first subsequent + * GetCurrentTransactionStopTimestamp() call. + * * These do not change as we enter and exit subtransactions, so we don't * keep them inside the TransactionState stack. */ @@ -865,15 +868,24 @@ GetCurrentStatementStartTimestamp(void) /* * GetCurrentTransactionStopTimestamp * - * We return current time if the transaction stop time hasn't been set - * (which can happen if we decide we don't need to log an XLOG record). + * If the transaction stop time hasn't already been set, which can happen if + * we decided we don't need to log an XLOG record, set xactStopTimestamp. */ TimestampTz GetCurrentTransactionStopTimestamp(void) { - if (xactStopTimestamp != 0) - return xactStopTimestamp; - return GetCurrentTimestamp(); + TransactionState s PG_USED_FOR_ASSERTS_ONLY = CurrentTransactionState; + + /* should only be called after commit / abort processing */ + Assert(s->state == TRANS_DEFAULT || + s->state == TRANS_COMMIT || + s->state == TRANS_ABORT || + s->state == TRANS_PREPARE); + + if (xactStopTimestamp == 0) + xactStopTimestamp = GetCurrentTimestamp(); + + return xactStopTimestamp; } /* @@ -891,15 +903,6 @@ SetCurrentStatementStartTimestamp(void) Assert(stmtStartTimestamp != 0); } -/* - * SetCurrentTransactionStopTimestamp - */ -static inline void -SetCurrentTransactionStopTimestamp(void) -{ - xactStopTimestamp = GetCurrentTimestamp(); -} - /* * GetCurrentTransactionNestLevel * @@ -1396,9 +1399,7 @@ RecordTransactionCommit(void) START_CRIT_SECTION(); MyProc->delayChkptFlags |= DELAY_CHKPT_START; - SetCurrentTransactionStopTimestamp(); - - XactLogCommitRecord(xactStopTimestamp, + XactLogCommitRecord(GetCurrentTransactionStopTimestamp(), nchildren, children, nrels, rels, ndroppedstats, droppedstats, nmsgs, invalMessages, @@ -1422,7 +1423,7 @@ RecordTransactionCommit(void) */ if (!replorigin || replorigin_session_origin_timestamp == 0) - replorigin_session_origin_timestamp = xactStopTimestamp; + replorigin_session_origin_timestamp = GetCurrentTransactionStopTimestamp(); TransactionTreeSetCommitTsData(xid, nchildren, children, replorigin_session_origin_timestamp, @@ -1754,8 +1755,7 @@ RecordTransactionAbort(bool isSubXact) xact_time = GetCurrentTimestamp(); else { - SetCurrentTransactionStopTimestamp(); - xact_time = xactStopTimestamp; + xact_time = GetCurrentTransactionStopTimestamp(); } XactLogAbortRecord(xact_time, -- 2.38.0
>From 5aee38649448e8b1f3c96e64555b59bd02708e3e Mon Sep 17 00:00:00 2001 From: Andres Freund <and...@anarazel.de> Date: Wed, 12 Oct 2022 14:45:39 -0700 Subject: [PATCH v5 2/3] pgstat: Track time of the last scan of a relation It can be useful to know when a relation has last been used, e.g., when evaluating whether an index is still required. It was already possible to infer the time of the last usage by tracking, e.g., pg_stat_all_indexes.idx_scan over time. But far from everybody does so. To make it easier to detect the last time a relation has been scanned, track that time in each relation's pgstat entry. To minimize overhead a) the timestamp is updated only when the backend pending stats entry is flushed to shared stats b) the last transaction's stop timestamp is used as the timestamp. Bumps catalog and stats format versions. Author: Dave Page <dp...@pgadmin.org> Reviewed-by: Andres Freund <and...@anarazel.de> Reviewed-by: Bruce Momjian <br...@momjian.us> Reviewed-by: Vik Fearing <v...@postgresfriends.org> Discussion: https://postgr.es/m/ca+ocxozrvhnfvepkweuhmzje+t1tfy816d9mzyc6ezwoous...@mail.gmail.com --- src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.dat | 4 +++ src/include/pgstat.h | 3 +- src/backend/catalog/system_views.sql | 3 ++ src/backend/utils/activity/pgstat_relation.c | 6 ++++ src/backend/utils/adt/pgstatfuncs.c | 13 +++++++++ doc/src/sgml/monitoring.sgml | 30 ++++++++++++++++++++ src/test/regress/expected/rules.out | 9 ++++++ 8 files changed, 68 insertions(+), 2 deletions(-) diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h index c1af6eaf5ff..e30f0262c59 100644 --- a/src/include/catalog/catversion.h +++ b/src/include/catalog/catversion.h @@ -57,6 +57,6 @@ */ /* yyyymmddN */ -#define CATALOG_VERSION_NO 202209291 +#define CATALOG_VERSION_NO 202210121 #endif diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 68bb032d3ea..62a5b8e655d 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -5252,6 +5252,10 @@ proname => 'pg_stat_get_numscans', provolatile => 's', proparallel => 'r', prorettype => 'int8', proargtypes => 'oid', prosrc => 'pg_stat_get_numscans' }, +{ oid => '9976', descr => 'statistics: time of the last scan for table/index', + proname => 'pg_stat_get_lastscan', provolatile => 's', proparallel => 'r', + prorettype => 'timestamptz', proargtypes => 'oid', + prosrc => 'pg_stat_get_lastscan' }, { oid => '1929', descr => 'statistics: number of tuples read by seqscan', proname => 'pg_stat_get_tuples_returned', provolatile => 's', proparallel => 'r', prorettype => 'int8', proargtypes => 'oid', diff --git a/src/include/pgstat.h b/src/include/pgstat.h index cc1d1dcb7d2..9e2ce6f0111 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -242,7 +242,7 @@ typedef struct PgStat_TableXactStatus * ------------------------------------------------------------ */ -#define PGSTAT_FILE_FORMAT_ID 0x01A5BCA8 +#define PGSTAT_FILE_FORMAT_ID 0x01A5BCA9 typedef struct PgStat_ArchiverStats { @@ -354,6 +354,7 @@ typedef struct PgStat_StatSubEntry typedef struct PgStat_StatTabEntry { PgStat_Counter numscans; + TimestampTz lastscan; PgStat_Counter tuples_returned; PgStat_Counter tuples_fetched; diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index 55f7ec79e05..2d8104b0907 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -656,8 +656,10 @@ CREATE VIEW pg_stat_all_tables AS N.nspname AS schemaname, C.relname AS relname, pg_stat_get_numscans(C.oid) AS seq_scan, + pg_stat_get_lastscan(C.oid) AS last_seq_scan, pg_stat_get_tuples_returned(C.oid) AS seq_tup_read, sum(pg_stat_get_numscans(I.indexrelid))::bigint AS idx_scan, + max(pg_stat_get_lastscan(I.indexrelid)) AS last_idx_scan, sum(pg_stat_get_tuples_fetched(I.indexrelid))::bigint + pg_stat_get_tuples_fetched(C.oid) AS idx_tup_fetch, pg_stat_get_tuples_inserted(C.oid) AS n_tup_ins, @@ -774,6 +776,7 @@ CREATE VIEW pg_stat_all_indexes AS C.relname AS relname, I.relname AS indexrelname, pg_stat_get_numscans(I.oid) AS idx_scan, + pg_stat_get_lastscan(I.oid) AS last_idx_scan, pg_stat_get_tuples_returned(I.oid) AS idx_tup_read, pg_stat_get_tuples_fetched(I.oid) AS idx_tup_fetch FROM pg_class C JOIN diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a846d9ffb65..55a355f583b 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -789,6 +789,12 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry = &shtabstats->stats; tabentry->numscans += lstats->t_counts.t_numscans; + if (lstats->t_counts.t_numscans) + { + TimestampTz t = GetCurrentTransactionStopTimestamp(); + if (t > tabentry->lastscan) + tabentry->lastscan = t; + } tabentry->tuples_returned += lstats->t_counts.t_tuples_returned; tabentry->tuples_fetched += lstats->t_counts.t_tuples_fetched; tabentry->tuples_inserted += lstats->t_counts.t_tuples_inserted; diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c index eadd8464ff2..85ac3e3f04f 100644 --- a/src/backend/utils/adt/pgstatfuncs.c +++ b/src/backend/utils/adt/pgstatfuncs.c @@ -52,6 +52,19 @@ pg_stat_get_numscans(PG_FUNCTION_ARGS) } +Datum +pg_stat_get_lastscan(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + PgStat_StatTabEntry *tabentry; + + if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL) + PG_RETURN_NULL(); + else + PG_RETURN_TIMESTAMPTZ(tabentry->lastscan); +} + + Datum pg_stat_get_tuples_returned(PG_FUNCTION_ARGS) { diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 342b20ebeb0..60a2026b0b0 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -4385,6 +4385,16 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i </para></entry> </row> + <row> + <entry role="catalog_table_entry"><para role="column_definition"> + <structfield>last_seq_scan</structfield> <type>timestamptz</type> + </para> + <para> + The time of the last sequential scan on this table, based on the + most recent transaction stop time + </para></entry> + </row> + <row> <entry role="catalog_table_entry"><para role="column_definition"> <structfield>seq_tup_read</structfield> <type>bigint</type> @@ -4403,6 +4413,16 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i </para></entry> </row> + <row> + <entry role="catalog_table_entry"><para role="column_definition"> + <structfield>last_idx_scan</structfield> <type>timestamptz</type> + </para> + <para> + The time of the last index scan on this table, based on the + most recent transaction stop time + </para></entry> + </row> + <row> <entry role="catalog_table_entry"><para role="column_definition"> <structfield>idx_tup_fetch</structfield> <type>bigint</type> @@ -4654,6 +4674,16 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i </para></entry> </row> + <row> + <entry role="catalog_table_entry"><para role="column_definition"> + <structfield>last_idx_scan</structfield> <type>timestamptz</type> + </para> + <para> + The time of the last scan on this index, based on the + most recent transaction stop time + </para></entry> + </row> + <row> <entry role="catalog_table_entry"><para role="column_definition"> <structfield>idx_tup_read</structfield> <type>bigint</type> diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 9dd137415e8..bfcd8ac9a06 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -1763,6 +1763,7 @@ pg_stat_all_indexes| SELECT c.oid AS relid, c.relname, i.relname AS indexrelname, pg_stat_get_numscans(i.oid) AS idx_scan, + pg_stat_get_lastscan(i.oid) AS last_idx_scan, pg_stat_get_tuples_returned(i.oid) AS idx_tup_read, pg_stat_get_tuples_fetched(i.oid) AS idx_tup_fetch FROM (((pg_class c @@ -1774,8 +1775,10 @@ pg_stat_all_tables| SELECT c.oid AS relid, n.nspname AS schemaname, c.relname, pg_stat_get_numscans(c.oid) AS seq_scan, + pg_stat_get_lastscan(c.oid) AS last_seq_scan, pg_stat_get_tuples_returned(c.oid) AS seq_tup_read, (sum(pg_stat_get_numscans(i.indexrelid)))::bigint AS idx_scan, + max(pg_stat_get_lastscan(i.indexrelid)) AS last_idx_scan, ((sum(pg_stat_get_tuples_fetched(i.indexrelid)))::bigint + pg_stat_get_tuples_fetched(c.oid)) AS idx_tup_fetch, pg_stat_get_tuples_inserted(c.oid) AS n_tup_ins, pg_stat_get_tuples_updated(c.oid) AS n_tup_upd, @@ -2107,6 +2110,7 @@ pg_stat_sys_indexes| SELECT pg_stat_all_indexes.relid, pg_stat_all_indexes.relname, pg_stat_all_indexes.indexrelname, pg_stat_all_indexes.idx_scan, + pg_stat_all_indexes.last_idx_scan, pg_stat_all_indexes.idx_tup_read, pg_stat_all_indexes.idx_tup_fetch FROM pg_stat_all_indexes @@ -2115,8 +2119,10 @@ pg_stat_sys_tables| SELECT pg_stat_all_tables.relid, pg_stat_all_tables.schemaname, pg_stat_all_tables.relname, pg_stat_all_tables.seq_scan, + pg_stat_all_tables.last_seq_scan, pg_stat_all_tables.seq_tup_read, pg_stat_all_tables.idx_scan, + pg_stat_all_tables.last_idx_scan, pg_stat_all_tables.idx_tup_fetch, pg_stat_all_tables.n_tup_ins, pg_stat_all_tables.n_tup_upd, @@ -2151,6 +2157,7 @@ pg_stat_user_indexes| SELECT pg_stat_all_indexes.relid, pg_stat_all_indexes.relname, pg_stat_all_indexes.indexrelname, pg_stat_all_indexes.idx_scan, + pg_stat_all_indexes.last_idx_scan, pg_stat_all_indexes.idx_tup_read, pg_stat_all_indexes.idx_tup_fetch FROM pg_stat_all_indexes @@ -2159,8 +2166,10 @@ pg_stat_user_tables| SELECT pg_stat_all_tables.relid, pg_stat_all_tables.schemaname, pg_stat_all_tables.relname, pg_stat_all_tables.seq_scan, + pg_stat_all_tables.last_seq_scan, pg_stat_all_tables.seq_tup_read, pg_stat_all_tables.idx_scan, + pg_stat_all_tables.last_idx_scan, pg_stat_all_tables.idx_tup_fetch, pg_stat_all_tables.n_tup_ins, pg_stat_all_tables.n_tup_upd, -- 2.38.0
>From 27569cdd1be0a9fd5d4fb672a459da09180eb9ea Mon Sep 17 00:00:00 2001 From: Andres Freund <and...@anarazel.de> Date: Wed, 12 Oct 2022 14:48:48 -0700 Subject: [PATCH v5 3/3] pgstat: Add tests for last_seq_scan, last_idx_scan Author: Reviewed-by: Discussion: https://postgr.es/m/ Backpatch: --- src/test/regress/expected/stats.out | 202 ++++++++++++++++++++++++++++ src/test/regress/sql/stats.sql | 86 ++++++++++++ 2 files changed, 288 insertions(+) diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out index f701da20697..257a6a9da9a 100644 --- a/src/test/regress/expected/stats.out +++ b/src/test/regress/expected/stats.out @@ -556,6 +556,208 @@ SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid); DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4; DROP TABLE prevstats; +----- +-- Test that last_seq_scan, last_idx_scan are correctly maintained +-- +-- Perform test using a temporary table. That way autovacuum etc won't +-- interfere. To be able to check that timestamps increase, we sleep for 100ms +-- between tests, assuming that there aren't systems with a coarser timestamp +-- granularity. +----- +BEGIN; +CREATE TEMPORARY TABLE test_last_scan(idx_col int primary key, noidx_col int); +INSERT INTO test_last_scan(idx_col, noidx_col) VALUES(1, 1); +SELECT pg_stat_force_next_flush(); + pg_stat_force_next_flush +-------------------------- + +(1 row) + +COMMIT; +SELECT pg_stat_reset_single_table_counters('test_last_scan'::regclass); + pg_stat_reset_single_table_counters +------------------------------------- + +(1 row) + +SELECT seq_scan, idx_scan FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + seq_scan | idx_scan +----------+---------- + 0 | 0 +(1 row) + +-- ensure we start out with exactly one index and sequential scan +BEGIN; +SET LOCAL enable_seqscan TO on; +SET LOCAL enable_indexscan TO on; +SET LOCAL enable_bitmapscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; + QUERY PLAN +---------------------------------- + Aggregate + -> Seq Scan on test_last_scan + Filter: (noidx_col = 1) +(3 rows) + +SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; + count +------- + 1 +(1 row) + +SET LOCAL enable_seqscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1; + QUERY PLAN +-------------------------------------------------------------- + Aggregate + -> Index Scan using test_last_scan_pkey on test_last_scan + Index Cond: (idx_col = 1) +(3 rows) + +SELECT count(*) FROM test_last_scan WHERE idx_col = 1; + count +------- + 1 +(1 row) + +SELECT pg_stat_force_next_flush(); + pg_stat_force_next_flush +-------------------------- + +(1 row) + +COMMIT; +-- fetch timestamps from before the next test +SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset +SELECT pg_sleep(0.1); -- assume a minimum timestamp granularity of 100ms + pg_sleep +---------- + +(1 row) + +-- cause one sequential scan +BEGIN; +SET LOCAL enable_seqscan TO on; +SET LOCAL enable_indexscan TO off; +SET LOCAL enable_bitmapscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; + QUERY PLAN +---------------------------------- + Aggregate + -> Seq Scan on test_last_scan + Filter: (noidx_col = 1) +(3 rows) + +SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; + count +------- + 1 +(1 row) + +SELECT pg_stat_force_next_flush(); + pg_stat_force_next_flush +-------------------------- + +(1 row) + +COMMIT; +-- check that just sequential scan stats were incremented +SELECT seq_scan, :'test_last_seq' < last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' = last_idx_scan AS idx_ok +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + seq_scan | seq_ok | idx_scan | idx_ok +----------+--------+----------+-------- + 2 | t | 1 | t +(1 row) + +-- fetch timestamps from before the next test +SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset +SELECT pg_sleep(0.1); + pg_sleep +---------- + +(1 row) + +-- cause one index scan +BEGIN; +SET LOCAL enable_seqscan TO off; +SET LOCAL enable_indexscan TO on; +SET LOCAL enable_bitmapscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1; + QUERY PLAN +-------------------------------------------------------------- + Aggregate + -> Index Scan using test_last_scan_pkey on test_last_scan + Index Cond: (idx_col = 1) +(3 rows) + +SELECT count(*) FROM test_last_scan WHERE idx_col = 1; + count +------- + 1 +(1 row) + +SELECT pg_stat_force_next_flush(); + pg_stat_force_next_flush +-------------------------- + +(1 row) + +COMMIT; +-- check that just index scan stats were incremented +SELECT seq_scan, :'test_last_seq' = last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + seq_scan | seq_ok | idx_scan | idx_ok +----------+--------+----------+-------- + 2 | t | 2 | t +(1 row) + +-- fetch timestamps from before the next test +SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset +SELECT pg_sleep(0.1); + pg_sleep +---------- + +(1 row) + +-- cause one bitmap index scan +BEGIN; +SET LOCAL enable_seqscan TO off; +SET LOCAL enable_indexscan TO off; +SET LOCAL enable_bitmapscan TO on; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1; + QUERY PLAN +------------------------------------------------------ + Aggregate + -> Bitmap Heap Scan on test_last_scan + Recheck Cond: (idx_col = 1) + -> Bitmap Index Scan on test_last_scan_pkey + Index Cond: (idx_col = 1) +(5 rows) + +SELECT count(*) FROM test_last_scan WHERE idx_col = 1; + count +------- + 1 +(1 row) + +SELECT pg_stat_force_next_flush(); + pg_stat_force_next_flush +-------------------------- + +(1 row) + +COMMIT; +-- check that just index scan stats were incremented +SELECT seq_scan, :'test_last_seq' = last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + seq_scan | seq_ok | idx_scan | idx_ok +----------+--------+----------+-------- + 2 | t | 3 | t +(1 row) + ----- -- Test that various stats views are being properly populated ----- diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql index eb081f65a42..f6270f7badb 100644 --- a/src/test/regress/sql/stats.sql +++ b/src/test/regress/sql/stats.sql @@ -290,6 +290,92 @@ DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_t DROP TABLE prevstats; +----- +-- Test that last_seq_scan, last_idx_scan are correctly maintained +-- +-- Perform test using a temporary table. That way autovacuum etc won't +-- interfere. To be able to check that timestamps increase, we sleep for 100ms +-- between tests, assuming that there aren't systems with a coarser timestamp +-- granularity. +----- + +BEGIN; +CREATE TEMPORARY TABLE test_last_scan(idx_col int primary key, noidx_col int); +INSERT INTO test_last_scan(idx_col, noidx_col) VALUES(1, 1); +SELECT pg_stat_force_next_flush(); +COMMIT; + +SELECT pg_stat_reset_single_table_counters('test_last_scan'::regclass); +SELECT seq_scan, idx_scan FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + +-- ensure we start out with exactly one index and sequential scan +BEGIN; +SET LOCAL enable_seqscan TO on; +SET LOCAL enable_indexscan TO on; +SET LOCAL enable_bitmapscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; +SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; +SET LOCAL enable_seqscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1; +SELECT count(*) FROM test_last_scan WHERE idx_col = 1; +SELECT pg_stat_force_next_flush(); +COMMIT; + +-- fetch timestamps from before the next test +SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset +SELECT pg_sleep(0.1); -- assume a minimum timestamp granularity of 100ms + +-- cause one sequential scan +BEGIN; +SET LOCAL enable_seqscan TO on; +SET LOCAL enable_indexscan TO off; +SET LOCAL enable_bitmapscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; +SELECT count(*) FROM test_last_scan WHERE noidx_col = 1; +SELECT pg_stat_force_next_flush(); +COMMIT; +-- check that just sequential scan stats were incremented +SELECT seq_scan, :'test_last_seq' < last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' = last_idx_scan AS idx_ok +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + +-- fetch timestamps from before the next test +SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset +SELECT pg_sleep(0.1); + +-- cause one index scan +BEGIN; +SET LOCAL enable_seqscan TO off; +SET LOCAL enable_indexscan TO on; +SET LOCAL enable_bitmapscan TO off; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1; +SELECT count(*) FROM test_last_scan WHERE idx_col = 1; +SELECT pg_stat_force_next_flush(); +COMMIT; +-- check that just index scan stats were incremented +SELECT seq_scan, :'test_last_seq' = last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + +-- fetch timestamps from before the next test +SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset +SELECT pg_sleep(0.1); + +-- cause one bitmap index scan +BEGIN; +SET LOCAL enable_seqscan TO off; +SET LOCAL enable_indexscan TO off; +SET LOCAL enable_bitmapscan TO on; +EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1; +SELECT count(*) FROM test_last_scan WHERE idx_col = 1; +SELECT pg_stat_force_next_flush(); +COMMIT; +-- check that just index scan stats were incremented +SELECT seq_scan, :'test_last_seq' = last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok +FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass; + + ----- -- Test that various stats views are being properly populated ----- -- 2.38.0
