From c7db46f953fdd6d5bf4a6198409910656528edbc Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot Date: Thu, 7 Aug 2025 14:41:09 +0000 Subject: [PATCH v1 03/10] Adding seq_tup_read to pg_stat_backend Adding per backend number of live rows fetched by sequential scans. XXX: Bump catversion. --- doc/src/sgml/monitoring.sgml | 9 +++++++++ src/backend/access/heap/heapam.c | 3 +++ src/backend/access/heap/heapam_handler.c | 1 + src/backend/catalog/system_views.sql | 1 + src/backend/utils/activity/pgstat_backend.c | 4 ++++ src/backend/utils/adt/pgstatfuncs.c | 14 +++++++++----- src/include/catalog/pg_proc.dat | 6 +++--- src/include/pgstat.h | 3 +++ src/test/regress/expected/rules.out | 3 ++- src/test/regress/expected/stats.out | 13 +++++++------ src/test/regress/sql/stats.sql | 7 ++++--- 11 files changed, 46 insertions(+), 18 deletions(-) 11.1% doc/src/sgml/ 6.9% src/backend/access/heap/ 4.7% src/backend/utils/activity/ 24.2% src/backend/utils/adt/ 11.7% src/include/catalog/ 4.8% src/include/ 20.7% src/test/regress/expected/ 14.3% src/test/regress/sql/ diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 6868af55db4..3fdc3d639e6 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -1231,6 +1231,15 @@ description | Waiting for a newly initialized WAL file to reach durable storage + + + seq_tup_read bigint + + + The number of live rows fetched by sequential scans. + + + stats_reset timestamp with time zone diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index d9d6fb6c6ea..8561693258f 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1379,6 +1379,7 @@ heap_getnext(TableScanDesc sscan, ScanDirection direction) */ pgstat_count_heap_getnext(scan->rs_base.rs_rd); + pgstat_count_backend_rel_seq_tup_read(); return &scan->rs_ctup; } @@ -1407,6 +1408,7 @@ heap_getnextslot(TableScanDesc sscan, ScanDirection direction, TupleTableSlot *s */ pgstat_count_heap_getnext(scan->rs_base.rs_rd); + pgstat_count_backend_rel_seq_tup_read(); ExecStoreBufferHeapTuple(&scan->rs_ctup, slot, scan->rs_cbuf); @@ -1555,6 +1557,7 @@ heap_getnextslot_tidrange(TableScanDesc sscan, ScanDirection direction, * the proper return buffer and return the tuple. */ pgstat_count_heap_getnext(scan->rs_base.rs_rd); + pgstat_count_backend_rel_seq_tup_read(); ExecStoreBufferHeapTuple(&scan->rs_ctup, slot, scan->rs_cbuf); return true; diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index cb4bc35c93e..050ed0a79a3 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -2335,6 +2335,7 @@ heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate, /* Count successfully-fetched tuples as heap fetches */ pgstat_count_heap_getnext(scan->rs_rd); + pgstat_count_backend_rel_seq_tup_read(); return true; } diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index 3ab7802cc5c..ea2f4785602 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -915,6 +915,7 @@ CREATE VIEW pg_stat_backend AS SELECT S.pid, S.seq_scan, + S.seq_tup_read, S.stats_reset FROM pg_stat_get_backend_statistics(NULL) AS S; diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c index 8797dac68c7..85da2d23fc7 100644 --- a/src/backend/utils/activity/pgstat_backend.c +++ b/src/backend/utils/activity/pgstat_backend.c @@ -287,6 +287,7 @@ pgstat_flush_backend_entry_rel(PgStat_EntryRef *entry_ref) (shbackendent->stats.stat += PendingBackendStats.pending_backendrel.stat) BACKENDREL_ACC(heap_scan); + BACKENDREL_ACC(seq_tup_read); #undef BACKENDREL_ACC /* @@ -459,3 +460,6 @@ CppConcat(pgstat_count_backend_rel_,stat)(void) \ /* pgstat_count_backend_rel_heap_scan */ PGSTAT_COUNT_BACKEND_FUNC(heap_scan) + +/* pgstat_count_backend_rel_seq_tup_read */ +PGSTAT_COUNT_BACKEND_FUNC(seq_tup_read) diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c index 2adfbdcb65c..c8f2b2a73d4 100644 --- a/src/backend/utils/adt/pgstatfuncs.c +++ b/src/backend/utils/adt/pgstatfuncs.c @@ -691,7 +691,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS) Datum pg_stat_get_backend_statistics(PG_FUNCTION_ARGS) { -#define PG_STAT_GET_BACKEND_STATS_COLS 3 +#define PG_STAT_GET_BACKEND_STATS_COLS 4 int num_backends = pgstat_fetch_stat_numbackends(); int curr_backend; int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0); @@ -708,6 +708,7 @@ pg_stat_get_backend_statistics(PG_FUNCTION_ARGS) LocalPgBackendStatus *local_beentry; PgBackendStatus *beentry; PgStat_Backend *backend_stats; + int i = 0; /* Get the next one in the list */ local_beentry = pgstat_get_local_beentry_by_index(curr_backend); @@ -719,17 +720,20 @@ pg_stat_get_backend_statistics(PG_FUNCTION_ARGS) backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL); - values[0] = Int32GetDatum(beentry->st_procpid); + values[i++] = Int32GetDatum(beentry->st_procpid); if (!backend_stats) continue; - values[1] = Int64GetDatum(backend_stats->heap_scan); + values[i++] = Int64GetDatum(backend_stats->heap_scan); + values[i++] = Int64GetDatum(backend_stats->seq_tup_read); if (backend_stats->stat_reset_timestamp != 0) - values[2] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp); + values[i] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp); else - nulls[2] = true; + nulls[i] = true; + + Assert(i + 1 == PG_STAT_GET_BACKEND_STATS_COLS); tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index e87200374d8..797a3f22db5 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -5646,9 +5646,9 @@ proname => 'pg_stat_get_backend_statistics', prorows => '100', proisstrict => 'f', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', proargtypes => 'int4', - proallargtypes => '{int4,int4,int8,timestamptz}', - proargmodes => '{i,o,o,o}', - proargnames => '{pid,pid,seq_scan,stats_reset}', + proallargtypes => '{int4,int4,int8,int8,timestamptz}', + proargmodes => '{i,o,o,o,o}', + proargnames => '{pid,pid,seq_scan,seq_tup_read,stats_reset}', prosrc => 'pg_stat_get_backend_statistics' }, { oid => '6318', descr => 'describe wait events', proname => 'pg_get_wait_events', procost => '10', prorows => '250', diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 7b4dacd27f8..d634fe8e746 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -491,11 +491,13 @@ typedef struct PgStat_Backend PgStat_BktypeIO io_stats; PgStat_WalCounters wal_counters; PgStat_Counter heap_scan; + PgStat_Counter seq_tup_read; } PgStat_Backend; typedef struct PgStat_BackendRelPending { PgStat_Counter heap_scan; + PgStat_Counter seq_tup_read; } PgStat_BackendRelPending; /* --------- @@ -576,6 +578,7 @@ extern void pgstat_create_backend(ProcNumber procnum); /* used to track backend relations related stats */ extern void pgstat_count_backend_rel_heap_scan(void); +extern void pgstat_count_backend_rel_seq_tup_read(void); /* * Functions in pgstat_bgwriter.c diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 63f8f12b8a5..faf73d956e8 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -1849,8 +1849,9 @@ pg_stat_archiver| SELECT archived_count, FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset); pg_stat_backend| SELECT pid, seq_scan, + seq_tup_read, stats_reset - FROM pg_stat_get_backend_statistics(NULL::integer) s(pid, seq_scan, stats_reset); + FROM pg_stat_get_backend_statistics(NULL::integer) s(pid, seq_scan, seq_tup_read, stats_reset); pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean, pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean, pg_stat_get_buf_alloc() AS buffers_alloc, diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out index 937bf4bfc5b..c96d8d2ecae 100644 --- a/src/test/regress/expected/stats.out +++ b/src/test/regress/expected/stats.out @@ -118,7 +118,7 @@ SELECT t.seq_scan, t.seq_tup_read, t.idx_scan, t.idx_tup_fetch, pg_catalog.pg_statio_user_tables AS b WHERE t.relname='tenk2' AND b.relname='tenk2'; COMMIT; -SELECT seq_scan AS seq_scan_before +SELECT seq_scan AS seq_scan_before, seq_tup_read AS seq_tup_read_before FROM pg_stat_backend WHERE pid = pg_backend_pid() \gset -- test effects of TRUNCATE on n_live_tup/n_dead_tup counters CREATE TABLE trunc_stats_test(id serial); @@ -221,12 +221,13 @@ SELECT st.seq_scan >= pr.seq_scan + 1, t | t | t | t (1 row) -SELECT seq_scan AS seq_scan_after +SELECT seq_scan AS seq_scan_after, seq_tup_read AS seq_tup_read_after FROM pg_stat_backend WHERE pid = pg_backend_pid() \gset -SELECT :seq_scan_after > :seq_scan_before; - ?column? ----------- - t +SELECT :seq_scan_after > :seq_scan_before, + :seq_tup_read_after > :seq_tup_read_before; + ?column? | ?column? +----------+---------- + t | t (1 row) SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages, diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql index b743352eadb..781b75d426a 100644 --- a/src/test/regress/sql/stats.sql +++ b/src/test/regress/sql/stats.sql @@ -38,7 +38,7 @@ SELECT t.seq_scan, t.seq_tup_read, t.idx_scan, t.idx_tup_fetch, WHERE t.relname='tenk2' AND b.relname='tenk2'; COMMIT; -SELECT seq_scan AS seq_scan_before +SELECT seq_scan AS seq_scan_before, seq_tup_read AS seq_tup_read_before FROM pg_stat_backend WHERE pid = pg_backend_pid() \gset -- test effects of TRUNCATE on n_live_tup/n_dead_tup counters @@ -125,10 +125,11 @@ SELECT st.seq_scan >= pr.seq_scan + 1, FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr WHERE st.relname='tenk2' AND cl.relname='tenk2'; -SELECT seq_scan AS seq_scan_after +SELECT seq_scan AS seq_scan_after, seq_tup_read AS seq_tup_read_after FROM pg_stat_backend WHERE pid = pg_backend_pid() \gset -SELECT :seq_scan_after > :seq_scan_before; +SELECT :seq_scan_after > :seq_scan_before, + :seq_tup_read_after > :seq_tup_read_before; SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages, st.idx_blks_read + st.idx_blks_hit >= pr.idx_blks + 1 -- 2.34.1