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Add backend-level statistics to pgstats

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This adds a new variable-numbered statistics kind in pgstats, where the
object ID key of the stats entries is based on the proc number of the
backends.  This acts as an upper-bound for the number of stats entries
that can exist at once.  The entries are created when a backend starts
after authentication succeeds, and are removed when the backend exits,
making the stats entry exist for as long as their backend is up and
running.  These are not written to the pgstats file at shutdown (note
that write_to_file is disabled, as a safety measure).

Currently, these stats include only information about the I/O generated
by a backend, using the same layer as pg_stat_io, except that it is now
possible to know how much activity is happening in each backend rather
than an overall aggregate of all the activity.  A function called
pg_stat_get_backend_io() is added to access this data depending on the
PID of a backend.  The existing structure could be expanded in the
future to add more information about other statistics related to
backends, depending on requirements or ideas.

Auxiliary processes are not included in this set of statistics.  These
are less interesting to have than normal backends as they have dedicated
entries in pg_stat_io, and stats kinds of their own.

This commit includes also pg_stat_reset_backend_stats(), function able
to reset all the stats associated to a single backend.

Bump catalog version and PGSTAT_FILE_FORMAT_ID.

Author: Bertrand Drouvot
Reviewed-by: Álvaro Herrera, Kyotaro Horiguchi, Michael Paquier, Nazir
Bilal Yavuz
Discussion: https://postgr.es/m/ZtXR+CtkEVVE/LHF@ip-10-97-1-34.eu-west-3.compute.internal
This commit is contained in:
Michael Paquier 2024-12-19 13:19:22 +09:00
parent ff7c40d7fd
commit 9aea73fc61
18 changed files with 552 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
doc/src/sgml/config.sgml
View File

@ -8403,9 +8403,11 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
displayed in <link linkend="monitoring-pg-stat-database-view">
<structname>pg_stat_database</structname></link>,
<link linkend="monitoring-pg-stat-io-view">
<structname>pg_stat_io</structname></link>, in the output of
<xref linkend="sql-explain"/> when the <literal>BUFFERS</literal> option
is used, in the output of <xref linkend="sql-vacuum"/> when
<structname>pg_stat_io</structname></link>, in the output of the
<link linkend="pg-stat-get-backend-io">
<function>pg_stat_get_backend_io()</function></link> function, in the
output of <xref linkend="sql-explain"/> when the <literal>BUFFERS</literal>
option is used, in the output of <xref linkend="sql-vacuum"/> when
the <literal>VERBOSE</literal> option is used, by autovacuum
for auto-vacuums and auto-analyzes, when <xref
linkend="guc-log-autovacuum-min-duration"/> is set and by

39
doc/src/sgml/monitoring.sgml
View File

@ -4790,6 +4790,27 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
<row>
<entry id="pg-stat-get-backend-io" role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_stat_get_backend_io</primary>
</indexterm>
<function>pg_stat_get_backend_io</function> ( <type>integer</type> )
<returnvalue>setof record</returnvalue>
</para>
<para>
Returns I/O statistics about the backend with the specified
process ID. The output fields are exactly the same as the ones in the
<structname>pg_stat_io</structname> view.
</para>
<para>
The function does not return I/O statistics for the checkpointer,
the background writer, the startup process and the autovacuum launcher
as they are already visible in the <structname>pg_stat_io</structname>
view and there is only one of each.
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
@ -4971,6 +4992,24 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_stat_reset_backend_stats</primary>
</indexterm>
<function>pg_stat_reset_backend_stats</function> ( <type>integer</type> )
<returnvalue>void</returnvalue>
</para>
<para>
Resets statistics for a single backend with the specified process ID
to zero.
</para>
<para>
This function is restricted to superusers by default, but other users
can be granted EXECUTE to run the function.
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>

2
src/backend/catalog/system_functions.sql
View File

@ -711,6 +711,8 @@ REVOKE EXECUTE ON FUNCTION pg_stat_reset_single_table_counters(oid) FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_reset_single_function_counters(oid) FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_reset_backend_stats(integer) FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_reset_replication_slot(text) FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_have_stats(text, oid, int8) FROM public;

1
src/backend/utils/activity/Makefile
View File

@ -20,6 +20,7 @@ OBJS = \
backend_status.o \
pgstat.o \
pgstat_archiver.o \
pgstat_backend.o \
pgstat_bgwriter.o \
pgstat_checkpointer.o \
pgstat_database.o \

4
src/backend/utils/activity/backend_status.c
View File

@ -426,6 +426,10 @@ pgstat_bestart(void)
PGSTAT_END_WRITE_ACTIVITY(vbeentry);
/* Create the backend statistics entry */
if (pgstat_tracks_backend_bktype(MyBackendType))
pgstat_create_backend(MyProcNumber);
/* Update app name to current GUC setting */
if (application_name)
pgstat_report_appname(application_name);

1
src/backend/utils/activity/meson.build
View File

@ -5,6 +5,7 @@ backend_sources += files(
'backend_status.c',
'pgstat.c',
'pgstat_archiver.c',
'pgstat_backend.c',
'pgstat_bgwriter.c',
'pgstat_checkpointer.c',
'pgstat_database.c',

21
src/backend/utils/activity/pgstat.c
View File

@ -77,6 +77,7 @@
*
* Each statistics kind is handled in a dedicated file:
* - pgstat_archiver.c
* - pgstat_backend.c
* - pgstat_bgwriter.c
* - pgstat_checkpointer.c
* - pgstat_database.c
@ -358,6 +359,22 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
.reset_timestamp_cb = pgstat_subscription_reset_timestamp_cb,
},
[PGSTAT_KIND_BACKEND] = {
.name = "backend",
.fixed_amount = false,
.write_to_file = false,
.accessed_across_databases = true,
.shared_size = sizeof(PgStatShared_Backend),
.shared_data_off = offsetof(PgStatShared_Backend, stats),
.shared_data_len = sizeof(((PgStatShared_Backend *) 0)->stats),
.pending_size = sizeof(PgStat_BackendPendingIO),
.flush_pending_cb = pgstat_backend_flush_cb,
.reset_timestamp_cb = pgstat_backend_reset_timestamp_cb,
},
/* stats for fixed-numbered (mostly 1) objects */
@ -602,6 +619,10 @@ pgstat_shutdown_hook(int code, Datum arg)
Assert(dlist_is_empty(&pgStatPending));
dlist_init(&pgStatPending);
/* drop the backend stats entry */
if (!pgstat_drop_entry(PGSTAT_KIND_BACKEND, InvalidOid, MyProcNumber))
pgstat_request_entry_refs_gc();
pgstat_detach_shmem();
#ifdef USE_ASSERT_CHECKING

188
src/backend/utils/activity/pgstat_backend.c Normal file
View File

@ -0,0 +1,188 @@
/* -------------------------------------------------------------------------
*
* pgstat_backend.c
* Implementation of backend statistics.
*
* This file contains the implementation of backend statistics. It is kept
* separate from pgstat.c to enforce the line between the statistics access /
* storage implementation and the details about individual types of
* statistics.
*
* This statistics kind uses a proc number as object ID for the hash table
* of pgstats. Entries are created each time a process is spawned, and are
* dropped when the process exits. These are not written to the pgstats file
* on disk.
*
* Copyright (c) 2001-2024, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/backend/utils/activity/pgstat_backend.c
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "utils/pgstat_internal.h"
/*
* Returns statistics of a backend by proc number.
*/
PgStat_Backend *
pgstat_fetch_stat_backend(ProcNumber procNumber)
{
PgStat_Backend *backend_entry;
backend_entry = (PgStat_Backend *) pgstat_fetch_entry(PGSTAT_KIND_BACKEND,
InvalidOid, procNumber);
return backend_entry;
}
/*
* Flush out locally pending backend statistics
*
* If no stats have been recorded, this function returns false.
*/
bool
pgstat_backend_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
{
PgStatShared_Backend *shbackendioent;
PgStat_BackendPendingIO *pendingent;
PgStat_BktypeIO *bktype_shstats;
if (!pgstat_lock_entry(entry_ref, nowait))
return false;
shbackendioent = (PgStatShared_Backend *) entry_ref->shared_stats;
bktype_shstats = &shbackendioent->stats.stats;
pendingent = (PgStat_BackendPendingIO *) entry_ref->pending;
for (int io_object = 0; io_object < IOOBJECT_NUM_TYPES; io_object++)
{
for (int io_context = 0; io_context < IOCONTEXT_NUM_TYPES; io_context++)
{
for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
{
instr_time time;
bktype_shstats->counts[io_object][io_context][io_op] +=
pendingent->counts[io_object][io_context][io_op];
time = pendingent->pending_times[io_object][io_context][io_op];
bktype_shstats->times[io_object][io_context][io_op] +=
INSTR_TIME_GET_MICROSEC(time);
}
}
}
pgstat_unlock_entry(entry_ref);
return true;
}
/*
* Simpler wrapper of pgstat_backend_flush_cb()
*/
void
pgstat_flush_backend(bool nowait)
{
PgStat_EntryRef *entry_ref;
if (!pgstat_tracks_backend_bktype(MyBackendType))
return;
entry_ref = pgstat_get_entry_ref(PGSTAT_KIND_BACKEND, InvalidOid,
MyProcNumber, false, NULL);
(void) pgstat_backend_flush_cb(entry_ref, nowait);
}
/*
* Create backend statistics entry for proc number.
*/
void
pgstat_create_backend(ProcNumber procnum)
{
PgStat_EntryRef *entry_ref;
PgStatShared_Backend *shstatent;
entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_BACKEND, InvalidOid,
procnum, NULL);
shstatent = (PgStatShared_Backend *) entry_ref->shared_stats;
/*
* NB: need to accept that there might be stats from an older backend,
* e.g. if we previously used this proc number.
*/
memset(&shstatent->stats, 0, sizeof(shstatent->stats));
}
/*
* Find or create a local PgStat_BackendPendingIO entry for proc number.
*/
PgStat_BackendPendingIO *
pgstat_prep_backend_pending(ProcNumber procnum)
{
PgStat_EntryRef *entry_ref;
entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_BACKEND, InvalidOid,
procnum, NULL);
return entry_ref->pending;
}
/*
* Backend statistics are not collected for all BackendTypes.
*
* The following BackendTypes do not participate in the backend stats
* subsystem:
* - The same and for the same reasons as in pgstat_tracks_io_bktype().
* - B_BG_WRITER, B_CHECKPOINTER, B_STARTUP and B_AUTOVAC_LAUNCHER because their
* I/O stats are already visible in pg_stat_io and there is only one of those.
*
* Function returns true if BackendType participates in the backend stats
* subsystem and false if it does not.
*
* When adding a new BackendType, also consider adding relevant restrictions to
* pgstat_tracks_io_object() and pgstat_tracks_io_op().
*/
bool
pgstat_tracks_backend_bktype(BackendType bktype)
{
/*
* List every type so that new backend types trigger a warning about
* needing to adjust this switch.
*/
switch (bktype)
{
case B_INVALID:
case B_AUTOVAC_LAUNCHER:
case B_DEAD_END_BACKEND:
case B_ARCHIVER:
case B_LOGGER:
case B_WAL_RECEIVER:
case B_WAL_WRITER:
case B_WAL_SUMMARIZER:
case B_BG_WRITER:
case B_CHECKPOINTER:
case B_STARTUP:
return false;
case B_AUTOVAC_WORKER:
case B_BACKEND:
case B_BG_WORKER:
case B_STANDALONE_BACKEND:
case B_SLOTSYNC_WORKER:
case B_WAL_SENDER:
return true;
}
return false;
}
void
pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
{
((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
}

25
src/backend/utils/activity/pgstat_io.c
View File

@ -20,14 +20,6 @@
#include "storage/bufmgr.h"
#include "utils/pgstat_internal.h"
typedef struct PgStat_PendingIO
{
PgStat_Counter counts[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
instr_time pending_times[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
} PgStat_PendingIO;
static PgStat_PendingIO PendingIOStats;
static bool have_iostats = false;
@ -87,6 +79,14 @@ pgstat_count_io_op_n(IOObject io_object, IOContext io_context, IOOp io_op, uint3
Assert((unsigned int) io_op < IOOP_NUM_TYPES);
Assert(pgstat_tracks_io_op(MyBackendType, io_object, io_context, io_op));
if (pgstat_tracks_backend_bktype(MyBackendType))
{
PgStat_PendingIO *entry_ref;
entry_ref = pgstat_prep_backend_pending(MyProcNumber);
entry_ref->counts[io_object][io_context][io_op] += cnt;
}
PendingIOStats.counts[io_object][io_context][io_op] += cnt;
have_iostats = true;
@ -148,6 +148,15 @@ pgstat_count_io_op_time(IOObject io_object, IOContext io_context, IOOp io_op,
INSTR_TIME_ADD(PendingIOStats.pending_times[io_object][io_context][io_op],
io_time);
if (pgstat_tracks_backend_bktype(MyBackendType))
{
PgStat_PendingIO *entry_ref;
entry_ref = pgstat_prep_backend_pending(MyProcNumber);
INSTR_TIME_ADD(entry_ref->pending_times[io_object][io_context][io_op],
io_time);
}
}
pgstat_count_io_op_n(io_object, io_context, io_op, cnt);

2
src/backend/utils/activity/pgstat_relation.c
View File

@ -264,6 +264,7 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
* VACUUM command has processed all tables and committed.
*/
pgstat_flush_io(false);
pgstat_flush_backend(false);
}
/*
@ -350,6 +351,7 @@ pgstat_report_analyze(Relation rel,
/* see pgstat_report_vacuum() */
pgstat_flush_io(false);
pgstat_flush_backend(false);
}
/*

99
src/backend/utils/adt/pgstatfuncs.c
View File

@ -1274,8 +1274,9 @@ pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
}
/*
* When adding a new column to the pg_stat_io view, add a new enum value
* here above IO_NUM_COLUMNS.
* When adding a new column to the pg_stat_io view and the
* pg_stat_get_backend_io() function, add a new enum value here above
* IO_NUM_COLUMNS.
*/
typedef enum io_stat_col
{
@ -1368,9 +1369,9 @@ pg_stat_us_to_ms(PgStat_Counter val_ms)
/*
* pg_stat_io_build_tuples
*
* Helper routine for pg_stat_get_io() filling a result tuplestore with one
* tuple for each object and each context supported by the caller, based on the
* contents of bktype_stats.
* Helper routine for pg_stat_get_io() and pg_stat_get_backend_io()
* filling a result tuplestore with one tuple for each object and each
* context supported by the caller, based on the contents of bktype_stats.
*/
static void
pg_stat_io_build_tuples(ReturnSetInfo *rsinfo,
@ -1494,6 +1495,70 @@ pg_stat_get_io(PG_FUNCTION_ARGS)
return (Datum) 0;
}
/*
* Returns I/O statistics for a backend with given PID.
*/
Datum
pg_stat_get_backend_io(PG_FUNCTION_ARGS)
{
ReturnSetInfo *rsinfo;
BackendType bktype;
int pid;
PGPROC *proc;
ProcNumber procNumber;
PgStat_Backend *backend_stats;
PgStat_BktypeIO *bktype_stats;
PgBackendStatus *beentry;
InitMaterializedSRF(fcinfo, 0);
rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
pid = PG_GETARG_INT32(0);
proc = BackendPidGetProc(pid);
/*
* This could be an auxiliary process but these do not report backend
* statistics due to pgstat_tracks_backend_bktype(), so there is no need
* for an extra call to AuxiliaryPidGetProc().
*/
if (!proc)
return (Datum) 0;
procNumber = GetNumberFromPGProc(proc);
beentry = pgstat_get_beentry_by_proc_number(procNumber);
if (!beentry)
return (Datum) 0;
backend_stats = pgstat_fetch_stat_backend(procNumber);
if (!backend_stats)
return (Datum) 0;
bktype = beentry->st_backendType;
/* if PID does not match, leave */
if (beentry->st_procpid != pid)
return (Datum) 0;
/* backend may be gone, so recheck in case */
if (bktype == B_INVALID)
return (Datum) 0;
bktype_stats = &backend_stats->stats;
/*
* In Assert builds, we can afford an extra loop through all of the
* counters (in pg_stat_io_build_tuples()), checking that only expected
* stats are non-zero, since it keeps the non-Assert code cleaner.
*/
Assert(pgstat_bktype_io_stats_valid(bktype_stats, bktype));
/* save tuples with data from this PgStat_BktypeIO */
pg_stat_io_build_tuples(rsinfo, bktype_stats, bktype,
backend_stats->stat_reset_timestamp);
return (Datum) 0;
}
/*
* Returns statistics of WAL activity
*/
@ -1799,6 +1864,30 @@ pg_stat_reset_single_function_counters(PG_FUNCTION_ARGS)
PG_RETURN_VOID();
}
/*
* Reset statistics of backend with given PID.
*/
Datum
pg_stat_reset_backend_stats(PG_FUNCTION_ARGS)
{
PGPROC *proc;
int backend_pid = PG_GETARG_INT32(0);
proc = BackendPidGetProc(backend_pid);
/*
* This could be an auxiliary process but these do not report backend
* statistics due to pgstat_tracks_backend_bktype(), so there is no need
* for an extra call to AuxiliaryPidGetProc().
*/
if (!proc)
PG_RETURN_VOID();
pgstat_reset(PGSTAT_KIND_BACKEND, InvalidOid, GetNumberFromPGProc(proc));
PG_RETURN_VOID();
}
/* Reset SLRU counters (a specific one or all of them). */
Datum
pg_stat_reset_slru(PG_FUNCTION_ARGS)

2
src/include/catalog/catversion.h
View File

@ -57,6 +57,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 202412112
#define CATALOG_VERSION_NO 202412191
#endif

13
src/include/catalog/pg_proc.dat
View File

@ -5913,6 +5913,15 @@
proargnames => '{backend_type,object,context,reads,read_time,writes,write_time,writebacks,writeback_time,extends,extend_time,op_bytes,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
prosrc => 'pg_stat_get_io' },
{ oid => '8806', descr => 'statistics: backend IO statistics',
proname => 'pg_stat_get_backend_io', prorows => '5', proretset => 't',
provolatile => 'v', proparallel => 'r', prorettype => 'record',
proargtypes => 'int4',
proallargtypes => '{int4,text,text,text,int8,float8,int8,float8,int8,float8,int8,float8,int8,int8,int8,int8,int8,float8,timestamptz}',
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{backend_pid,backend_type,object,context,reads,read_time,writes,write_time,writebacks,writeback_time,extends,extend_time,op_bytes,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
prosrc => 'pg_stat_get_backend_io' },
{ oid => '1136', descr => 'statistics: information about WAL activity',
proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
proparallel => 'r', prorettype => 'record', proargtypes => '',
@ -6052,6 +6061,10 @@
proname => 'pg_stat_reset_single_function_counters', provolatile => 'v',
prorettype => 'void', proargtypes => 'oid',
prosrc => 'pg_stat_reset_single_function_counters' },
{ oid => '8807', descr => 'statistics: reset statistics for a single backend',
proname => 'pg_stat_reset_backend_stats', provolatile => 'v',
prorettype => 'void', proargtypes => 'int4',
prosrc => 'pg_stat_reset_backend_stats' },
{ oid => '2307',
descr => 'statistics: reset collected statistics for a single SLRU',
proname => 'pg_stat_reset_slru', proisstrict => 'f', provolatile => 'v',

36
src/include/pgstat.h
View File

@ -49,14 +49,15 @@
#define PGSTAT_KIND_FUNCTION 3 /* per-function statistics */
#define PGSTAT_KIND_REPLSLOT 4 /* per-slot statistics */
#define PGSTAT_KIND_SUBSCRIPTION 5 /* per-subscription statistics */
#define PGSTAT_KIND_BACKEND 6 /* per-backend statistics */
/* stats for fixed-numbered objects */
#define PGSTAT_KIND_ARCHIVER 6
#define PGSTAT_KIND_BGWRITER 7
#define PGSTAT_KIND_CHECKPOINTER 8
#define PGSTAT_KIND_IO 9
#define PGSTAT_KIND_SLRU 10
#define PGSTAT_KIND_WAL 11
#define PGSTAT_KIND_ARCHIVER 7
#define PGSTAT_KIND_BGWRITER 8
#define PGSTAT_KIND_CHECKPOINTER 9
#define PGSTAT_KIND_IO 10
#define PGSTAT_KIND_SLRU 11
#define PGSTAT_KIND_WAL 12
#define PGSTAT_KIND_BUILTIN_MIN PGSTAT_KIND_DATABASE
#define PGSTAT_KIND_BUILTIN_MAX PGSTAT_KIND_WAL
@ -266,7 +267,7 @@ typedef struct PgStat_TableXactStatus
* ------------------------------------------------------------
*/
#define PGSTAT_FILE_FORMAT_ID 0x01A5BCAF
#define PGSTAT_FILE_FORMAT_ID 0x01A5BCB0
typedef struct PgStat_ArchiverStats
{
@ -362,12 +363,26 @@ typedef struct PgStat_BktypeIO
PgStat_Counter times[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
} PgStat_BktypeIO;
typedef struct PgStat_PendingIO
{
PgStat_Counter counts[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
instr_time pending_times[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
} PgStat_PendingIO;
typedef struct PgStat_IO
{
TimestampTz stat_reset_timestamp;
PgStat_BktypeIO stats[BACKEND_NUM_TYPES];
} PgStat_IO;
/* Backend statistics store the same amount of IO data as PGSTAT_KIND_IO */
typedef PgStat_PendingIO PgStat_BackendPendingIO;
typedef struct PgStat_Backend
{
TimestampTz stat_reset_timestamp;
PgStat_BktypeIO stats;
} PgStat_Backend;
typedef struct PgStat_StatDBEntry
{
@ -549,6 +564,13 @@ extern bool pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid);
extern void pgstat_report_archiver(const char *xlog, bool failed);
extern PgStat_ArchiverStats *pgstat_fetch_stat_archiver(void);
/*
* Functions in pgstat_backend.c
*/
extern PgStat_Backend *pgstat_fetch_stat_backend(ProcNumber procNumber);
extern bool pgstat_tracks_backend_bktype(BackendType bktype);
extern void pgstat_create_backend(ProcNumber procnum);
/*
* Functions in pgstat_bgwriter.c

14
src/include/utils/pgstat_internal.h
View File

@ -450,6 +450,11 @@ typedef struct PgStatShared_ReplSlot
PgStat_StatReplSlotEntry stats;
} PgStatShared_ReplSlot;
typedef struct PgStatShared_Backend
{
PgStatShared_Common header;
PgStat_Backend stats;
} PgStatShared_Backend;
/*
* Central shared memory entry for the cumulative stats system.
@ -604,6 +609,15 @@ extern void pgstat_archiver_init_shmem_cb(void *stats);
extern void pgstat_archiver_reset_all_cb(TimestampTz ts);
extern void pgstat_archiver_snapshot_cb(void);
/*
* Functions in pgstat_backend.c
*/
extern void pgstat_flush_backend(bool nowait);
extern PgStat_BackendPendingIO *pgstat_prep_backend_pending(ProcNumber procnum);
extern bool pgstat_backend_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
/*
* Functions in pgstat_bgwriter.c

82
src/test/regress/expected/stats.out
View File

@ -1249,7 +1249,8 @@ SELECT pg_stat_get_subscription_stats(NULL);
(1 row)
-- Test that the following operations are tracked in pg_stat_io:
-- Test that the following operations are tracked in pg_stat_io and in
-- backend stats:
-- - reads of target blocks into shared buffers
-- - writes of shared buffers to permanent storage
-- - extends of relations using shared buffers
@ -1259,11 +1260,19 @@ SELECT pg_stat_get_subscription_stats(NULL);
-- be sure of the state of shared buffers at the point the test is run.
-- Create a regular table and insert some data to generate IOCONTEXT_NORMAL
-- extends.
SELECT pid AS checkpointer_pid FROM pg_stat_activity
WHERE backend_type = 'checkpointer' \gset
SELECT sum(extends) AS io_sum_shared_before_extends
FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
SELECT sum(extends) AS my_io_sum_shared_before_extends
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE context = 'normal' AND object = 'relation' \gset
SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
FROM pg_stat_io
WHERE object = 'relation' \gset io_sum_shared_before_
SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE object = 'relation' \gset my_io_sum_shared_before_
CREATE TABLE test_io_shared(a int);
INSERT INTO test_io_shared SELECT i FROM generate_series(1,100)i;
SELECT pg_stat_force_next_flush();
@ -1280,8 +1289,17 @@ SELECT :io_sum_shared_after_extends > :io_sum_shared_before_extends;
t
(1 row)
SELECT sum(extends) AS my_io_sum_shared_after_extends
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE context = 'normal' AND object = 'relation' \gset
SELECT :my_io_sum_shared_after_extends > :my_io_sum_shared_before_extends;
?column?
----------
t
(1 row)
-- After a checkpoint, there should be some additional IOCONTEXT_NORMAL writes
-- and fsyncs.
-- and fsyncs in the global stats (not for the backend).
-- See comment above for rationale for two explicit CHECKPOINTs.
CHECKPOINT;
CHECKPOINT;
@ -1301,6 +1319,23 @@ SELECT current_setting('fsync') = 'off'
t
(1 row)
SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE object = 'relation' \gset my_io_sum_shared_after_
SELECT :my_io_sum_shared_after_writes >= :my_io_sum_shared_before_writes;
?column?
----------
t
(1 row)
SELECT current_setting('fsync') = 'off'
OR (:my_io_sum_shared_after_fsyncs = :my_io_sum_shared_before_fsyncs
AND :my_io_sum_shared_after_fsyncs= 0);
?column?
----------
t
(1 row)
-- Change the tablespace so that the table is rewritten directly, then SELECT
-- from it to cause it to be read back into shared buffers.
SELECT sum(reads) AS io_sum_shared_before_reads
@ -1521,6 +1556,8 @@ SELECT pg_stat_have_stats('io', 0, 0);
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS io_stats_pre_reset
FROM pg_stat_io \gset
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_pre_reset
FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
SELECT pg_stat_reset_shared('io');
pg_stat_reset_shared
----------------------
@ -1535,6 +1572,47 @@ SELECT :io_stats_post_reset < :io_stats_pre_reset;
t
(1 row)
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_post_reset
FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
-- pg_stat_reset_shared() did not reset backend IO stats
SELECT :my_io_stats_pre_reset <= :my_io_stats_post_reset;
?column?
----------
t
(1 row)
-- but pg_stat_reset_backend_stats() does
SELECT pg_stat_reset_backend_stats(pg_backend_pid());
pg_stat_reset_backend_stats
-----------------------------
(1 row)
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_post_backend_reset
FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
SELECT :my_io_stats_pre_reset > :my_io_stats_post_backend_reset;
?column?
----------
t
(1 row)
-- Check invalid input for pg_stat_get_backend_io()
SELECT pg_stat_get_backend_io(NULL);
pg_stat_get_backend_io
------------------------
(0 rows)
SELECT pg_stat_get_backend_io(0);
pg_stat_get_backend_io
------------------------
(0 rows)
-- Auxiliary processes return no data.
SELECT pg_stat_get_backend_io(:checkpointer_pid);
pg_stat_get_backend_io
------------------------
(0 rows)
-- test BRIN index doesn't block HOT update
CREATE TABLE brin_hot (
id integer PRIMARY KEY,

40
src/test/regress/sql/stats.sql
View File

@ -595,7 +595,8 @@ SELECT pg_stat_get_replication_slot(NULL);
SELECT pg_stat_get_subscription_stats(NULL);
-- Test that the following operations are tracked in pg_stat_io:
-- Test that the following operations are tracked in pg_stat_io and in
-- backend stats:
-- - reads of target blocks into shared buffers
-- - writes of shared buffers to permanent storage
-- - extends of relations using shared buffers
@ -607,20 +608,32 @@ SELECT pg_stat_get_subscription_stats(NULL);
-- Create a regular table and insert some data to generate IOCONTEXT_NORMAL
-- extends.
SELECT pid AS checkpointer_pid FROM pg_stat_activity
WHERE backend_type = 'checkpointer' \gset
SELECT sum(extends) AS io_sum_shared_before_extends
FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
SELECT sum(extends) AS my_io_sum_shared_before_extends
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE context = 'normal' AND object = 'relation' \gset
SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
FROM pg_stat_io
WHERE object = 'relation' \gset io_sum_shared_before_
SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE object = 'relation' \gset my_io_sum_shared_before_
CREATE TABLE test_io_shared(a int);
INSERT INTO test_io_shared SELECT i FROM generate_series(1,100)i;
SELECT pg_stat_force_next_flush();
SELECT sum(extends) AS io_sum_shared_after_extends
FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
SELECT :io_sum_shared_after_extends > :io_sum_shared_before_extends;
SELECT sum(extends) AS my_io_sum_shared_after_extends
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE context = 'normal' AND object = 'relation' \gset
SELECT :my_io_sum_shared_after_extends > :my_io_sum_shared_before_extends;
-- After a checkpoint, there should be some additional IOCONTEXT_NORMAL writes
-- and fsyncs.
-- and fsyncs in the global stats (not for the backend).
-- See comment above for rationale for two explicit CHECKPOINTs.
CHECKPOINT;
CHECKPOINT;
@ -630,6 +643,13 @@ SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
SELECT :io_sum_shared_after_writes > :io_sum_shared_before_writes;
SELECT current_setting('fsync') = 'off'
OR :io_sum_shared_after_fsyncs > :io_sum_shared_before_fsyncs;
SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
FROM pg_stat_get_backend_io(pg_backend_pid())
WHERE object = 'relation' \gset my_io_sum_shared_after_
SELECT :my_io_sum_shared_after_writes >= :my_io_sum_shared_before_writes;
SELECT current_setting('fsync') = 'off'
OR (:my_io_sum_shared_after_fsyncs = :my_io_sum_shared_before_fsyncs
AND :my_io_sum_shared_after_fsyncs= 0);
-- Change the tablespace so that the table is rewritten directly, then SELECT
-- from it to cause it to be read back into shared buffers.
@ -762,11 +782,27 @@ SELECT :io_sum_bulkwrite_strategy_extends_after > :io_sum_bulkwrite_strategy_ext
SELECT pg_stat_have_stats('io', 0, 0);
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS io_stats_pre_reset
FROM pg_stat_io \gset
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_pre_reset
FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
SELECT pg_stat_reset_shared('io');
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS io_stats_post_reset
FROM pg_stat_io \gset
SELECT :io_stats_post_reset < :io_stats_pre_reset;
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_post_reset
FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
-- pg_stat_reset_shared() did not reset backend IO stats
SELECT :my_io_stats_pre_reset <= :my_io_stats_post_reset;
-- but pg_stat_reset_backend_stats() does
SELECT pg_stat_reset_backend_stats(pg_backend_pid());
SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_post_backend_reset
FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
SELECT :my_io_stats_pre_reset > :my_io_stats_post_backend_reset;
-- Check invalid input for pg_stat_get_backend_io()
SELECT pg_stat_get_backend_io(NULL);
SELECT pg_stat_get_backend_io(0);
-- Auxiliary processes return no data.
SELECT pg_stat_get_backend_io(:checkpointer_pid);
-- test BRIN index doesn't block HOT update
CREATE TABLE brin_hot (

3
src/tools/pgindent/typedefs.list
View File

@ -2121,6 +2121,7 @@ PgFdwSamplingMethod
PgFdwScanState
PgIfAddrCallback
PgStatShared_Archiver
PgStatShared_Backend
PgStatShared_BgWriter
PgStatShared_Checkpointer
PgStatShared_Common
@ -2136,6 +2137,8 @@ PgStatShared_SLRU
PgStatShared_Subscription
PgStatShared_Wal
PgStat_ArchiverStats
PgStat_Backend
PgStat_BackendPendingIO
PgStat_BackendSubEntry
PgStat_BgWriterStats
PgStat_BktypeIO