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Add write_to_file to PgStat_KindInfo for pgstats kinds

author Michael Paquier <michael@paquier.xyz>

2024年11月22日 01:12:26 +0000 (10:12 +0900)

committer Michael Paquier <michael@paquier.xyz>

2024年11月22日 01:12:26 +0000 (10:12 +0900)

This new field controls if entries of a stats kind should be written or
not to the on-disk pgstats file when shutting down an instance. This
affects both fixed and variable-numbered kinds.

This is useful for custom statistics by itself, and a patch is under
discussion to add a new builtin stats kind where the write of the stats
is not necessary. All the built-in stats kinds, as well as the two
custom stats kinds in the test module injection_points, set this flag to
"true" for now, so as stats entries are written to the on-disk pgstats
file.

Author: Bertrand Drouvot
Reviewed-by: Nazir Bilal Yavuz
Discussion: https://postgr.es/m/Zz7T47nHwYgeYwOe@ip-10-97-1-34.eu-west-3.compute.internal

src/backend/utils/activity/pgstat.c patch | blob | blame | history

src/include/utils/pgstat_internal.h patch | blob | blame | history

src/test/modules/injection_points/injection_stats.c patch | blob | blame | history

src/test/modules/injection_points/injection_stats_fixed.c patch | blob | blame | history

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c

index ea8c5691e87501704db6e04d389f9cb6c4be8887..6f8d237826603e64e0c0a34228c873b8cc5e081b 100644 (file)

--- a/src/backend/utils/activity/pgstat.c

+++ b/src/backend/utils/activity/pgstat.c

@@ -12,7 +12,8 @@

* Statistics are loaded from the filesystem during startup (by the startup

* process), unless preceded by a crash, in which case all stats are

* discarded. They are written out by the checkpointer process just before

- * shutting down, except when shutting down in immediate mode.

+ * shutting down (if the stats kind allows it), except when shutting down in

+ * immediate mode.

* Fixed-numbered stats are stored in plain (non-dynamic) shared memory.

@@ -281,6 +282,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "database",

.fixed_amount = false,

+ .write_to_file = true,

/* so pg_stat_database entries can be seen in all databases */

.accessed_across_databases = true,

@@ -297,6 +299,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "relation",

.fixed_amount = false,

+ .write_to_file = true,

.shared_size = sizeof(PgStatShared_Relation),

.shared_data_off = offsetof(PgStatShared_Relation, stats),

@@ -311,6 +314,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "function",

.fixed_amount = false,

+ .write_to_file = true,

.shared_size = sizeof(PgStatShared_Function),

.shared_data_off = offsetof(PgStatShared_Function, stats),

@@ -324,6 +328,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "replslot",

.fixed_amount = false,

+ .write_to_file = true,

.accessed_across_databases = true,

@@ -340,6 +345,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "subscription",

.fixed_amount = false,

+ .write_to_file = true,

/* so pg_stat_subscription_stats entries can be seen in all databases */

.accessed_across_databases = true,

@@ -359,6 +365,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "archiver",

.fixed_amount = true,

+ .write_to_file = true,

.snapshot_ctl_off = offsetof(PgStat_Snapshot, archiver),

.shared_ctl_off = offsetof(PgStat_ShmemControl, archiver),

@@ -374,6 +381,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "bgwriter",

.fixed_amount = true,

+ .write_to_file = true,

.snapshot_ctl_off = offsetof(PgStat_Snapshot, bgwriter),

.shared_ctl_off = offsetof(PgStat_ShmemControl, bgwriter),

@@ -389,6 +397,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "checkpointer",

.fixed_amount = true,

+ .write_to_file = true,

.snapshot_ctl_off = offsetof(PgStat_Snapshot, checkpointer),

.shared_ctl_off = offsetof(PgStat_ShmemControl, checkpointer),

@@ -404,6 +413,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "io",

.fixed_amount = true,

+ .write_to_file = true,

.snapshot_ctl_off = offsetof(PgStat_Snapshot, io),

.shared_ctl_off = offsetof(PgStat_ShmemControl, io),

@@ -421,6 +431,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "slru",

.fixed_amount = true,

+ .write_to_file = true,

.snapshot_ctl_off = offsetof(PgStat_Snapshot, slru),

.shared_ctl_off = offsetof(PgStat_ShmemControl, slru),

@@ -438,6 +449,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]

.name = "wal",

.fixed_amount = true,

+ .write_to_file = true,

.snapshot_ctl_off = offsetof(PgStat_Snapshot, wal),

.shared_ctl_off = offsetof(PgStat_ShmemControl, wal),

@@ -1617,6 +1629,10 @@ pgstat_write_statsfile(XLogRecPtr redo)

if (pgstat_is_kind_builtin(kind))

Assert(info->snapshot_ctl_off != 0);

+ /* skip if no need to write to file */

+ if (!info->write_to_file)

+ continue;

pgstat_build_snapshot_fixed(kind);

if (pgstat_is_kind_builtin(kind))

ptr = ((char *) &pgStatLocal.snapshot) + info->snapshot_ctl_off;

@@ -1663,6 +1679,10 @@ pgstat_write_statsfile(XLogRecPtr redo)

/* if not dropped the valid-entry refcount should exist */

Assert(pg_atomic_read_u32(&ps->refcount) > 0);

+ /* skip if no need to write to file */

+ if (!kind_info->write_to_file)

+ continue;

if (!kind_info->to_serialized_name)

{

/* normal stats entry, identified by PgStat_HashKey */

diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h

index 437db06910b4199d6db2f4684332a33864977da9..7338bc1e28ec4f770669f155460264b771b41eaf 100644 (file)

--- a/src/include/utils/pgstat_internal.h

+++ b/src/include/utils/pgstat_internal.h

@@ -213,6 +213,9 @@ typedef struct PgStat_KindInfo

bool accessed_across_databases:1;

+ /* Should stats be written to the on-disk stats file? */

+ bool write_to_file:1;

* The size of an entry in the shared stats hash table (pointed to by

* PgStatShared_HashEntry->body). For fixed-numbered statistics, this is

diff --git a/src/test/modules/injection_points/injection_stats.c b/src/test/modules/injection_points/injection_stats.c

index d89d0559134fab259a29248060ab6c71b417326a..e16b9db284519201f1f982e30452fd5329c6db27 100644 (file)

--- a/src/test/modules/injection_points/injection_stats.c

+++ b/src/test/modules/injection_points/injection_stats.c

@@ -39,6 +39,7 @@ static bool injection_stats_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);

static const PgStat_KindInfo injection_stats = {

.name = "injection_points",

.fixed_amount = false, /* Bounded by the number of points */

+ .write_to_file = true,

/* Injection points are system-wide */

.accessed_across_databases = true,

diff --git a/src/test/modules/injection_points/injection_stats_fixed.c b/src/test/modules/injection_points/injection_stats_fixed.c

index 2fed178b7a65696e3f0954d7440ee98551513cec..c5b0bb8cf041629eac82e3852a8f2c6d0439343e 100644 (file)

--- a/src/test/modules/injection_points/injection_stats_fixed.c

+++ b/src/test/modules/injection_points/injection_stats_fixed.c

@@ -50,6 +50,7 @@ static void injection_stats_fixed_snapshot_cb(void);

static const PgStat_KindInfo injection_stats_fixed = {

.name = "injection_points_fixed",

.fixed_amount = true,

+ .write_to_file = true,

.shared_size = sizeof(PgStat_StatInjFixedEntry),

.shared_data_off = offsetof(PgStatShared_InjectionPointFixed, stats),

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