Dne 23.12.2010 20:09, Robert Haas napsal(a):
> 2010/12/23 Tomas Vondra <t...@fuzzy.cz>:
>> Dne 20.12.2010 00:03, Tom Lane napsal(a):
>>> I wrote:
>>>> That is not the number of interest. The number of interest is that it's
>>>> 8 bytes added onto a struct that currently contains 11 of 'em; in other
>>>> words a 9% increase in the size of the stats file, and consequently
>>>> about a 9% increase in the cost of updating it.
>>>
>>> Wups, sorry, I was looking at the wrong struct. It's actually an
>>> addition of 1 doubleword to a struct of 21 of 'em, or about 5%.
>>> That's still an awful lot in comparison to the prospective usefulness
>>> of the information.
>>>
>>> regards, tom lane
>>>
>>
>> OK, so here goes the simplified patch - it tracks one reset timestamp
>> for a background writer and for each database.
>
> I think you forgot the attachment.
Yes, I did. Thanks!
Tomas
>From da2154954a547c143cd0d130597411911f339c07 Mon Sep 17 00:00:00 2001
From: vampire <vamp...@rimmer.reddwarf>
Date: Thu, 23 Dec 2010 18:40:48 +0100
Subject: [PATCH] Track timestamp of the last stats reset (for each database and
a background writer).
This is simplified version of the previous patch, that kept a timestamp for each
database, table, index and function and for the background writer. This does not
keep the timestamp for individual objects, but if stats for a
table/index/function
are reset, the timestamp for the whole database is updated.
---
doc/src/sgml/monitoring.sgml | 18 ++++++++++++++++++
src/backend/catalog/system_views.sql | 6 ++++--
src/backend/postmaster/pgstat.c | 13 +++++++++++++
src/backend/utils/adt/pgstatfuncs.c | 26 ++++++++++++++++++++++++++
src/include/catalog/pg_proc.h | 4 ++++
src/include/pgstat.h | 5 +++++
6 files changed, 70 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 5fd0213..99e091d 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -600,6 +600,15 @@ postgres: <replaceable>user</> <replaceable>database</>
<replaceable>host</> <re
</row>
<row>
+
<entry><literal><function>pg_stat_get_db_stat_reset_time</function>(<type>oid</type>)</literal></entry>
+ <entry><type>timestamptz</type></entry>
+ <entry>
+ Time of the last reset of statistics for this database (as a result of
executing
+ <function>pg_stat_reset</function> function) or any object within it
(table or index).
+ </entry>
+ </row>
+
+ <row>
<entry><literal><function>pg_stat_get_numscans</function>(<type>oid</type>)</literal></entry>
<entry><type>bigint</type></entry>
<entry>
@@ -1062,6 +1071,15 @@ postgres: <replaceable>user</> <replaceable>database</>
<replaceable>host</> <re
<varname>bgwriter_lru_maxpages</varname> parameter
</entry>
</row>
+
+ <row>
+
<entry><literal><function>pg_stat_get_bgwriter_stat_reset_time()</function></literal></entry>
+ <entry><type>timestamptz</type></entry>
+ <entry>
+ Time of the last reset of statistics for the background writer (as a
result of executing
+ <function>pg_stat_reset_shared('bgwriter')</function>)
+ </entry>
+ </row>
<row>
<entry><literal><function>pg_stat_get_buf_written_backend()</function></literal></entry>
diff --git a/src/backend/catalog/system_views.sql
b/src/backend/catalog/system_views.sql
index 346eaaf..da92438 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -502,7 +502,8 @@ CREATE VIEW pg_stat_database AS
pg_stat_get_db_tuples_fetched(D.oid) AS tup_fetched,
pg_stat_get_db_tuples_inserted(D.oid) AS tup_inserted,
pg_stat_get_db_tuples_updated(D.oid) AS tup_updated,
- pg_stat_get_db_tuples_deleted(D.oid) AS tup_deleted
+ pg_stat_get_db_tuples_deleted(D.oid) AS tup_deleted,
+ pg_stat_get_db_stat_reset_time(D.oid) AS stats_reset
FROM pg_database D;
CREATE VIEW pg_stat_user_functions AS
@@ -538,7 +539,8 @@ CREATE VIEW pg_stat_bgwriter AS
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_written_backend() AS buffers_backend,
pg_stat_get_buf_fsync_backend() AS buffers_backend_fsync,
- pg_stat_get_buf_alloc() AS buffers_alloc;
+ pg_stat_get_buf_alloc() AS buffers_alloc,
+ pg_stat_get_bgwriter_stat_reset_time() AS stats_reset;
CREATE VIEW pg_user_mappings AS
SELECT
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 856daa7..66e0b69 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3130,6 +3130,8 @@ pgstat_get_db_entry(Oid databaseid, bool create)
result->n_tuples_deleted = 0;
result->last_autovac_time = 0;
+ result->stat_reset_timestamp = GetCurrentTimestamp();
+
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
@@ -3408,6 +3410,12 @@ pgstat_read_statsfile(Oid onlydb, bool permanent)
* load an existing statsfile.
*/
memset(&globalStats, 0, sizeof(globalStats));
+
+ /*
+ * Set the current timestamp (will be kept only in case we can't load an
+ * existing statsfile.
+ */
+ globalStats.stat_reset_timestamp = GetCurrentTimestamp();
/*
* Try to open the status file. If it doesn't exist, the backends simply
@@ -4022,6 +4030,8 @@ pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int
len)
dbentry->n_tuples_deleted = 0;
dbentry->last_autovac_time = 0;
+ dbentry->stat_reset_timestamp = GetCurrentTimestamp();
+
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
@@ -4053,6 +4063,7 @@
pgstat_recv_resetsharedcounter(PgStat_MsgResetsharedcounter *msg, int len)
{
/* Reset the global background writer statistics for the
cluster. */
memset(&globalStats, 0, sizeof(globalStats));
+ globalStats.stat_reset_timestamp = GetCurrentTimestamp();
}
/*
@@ -4077,6 +4088,8 @@
pgstat_recv_resetsinglecounter(PgStat_MsgResetsinglecounter *msg, int len)
if (!dbentry)
return;
+ /* Set the reset timestamp for the whole database */
+ dbentry->stat_reset_timestamp = GetCurrentTimestamp();
/* Remove object if it exists, ignore it if not */
if (msg->m_resettype == RESET_TABLE)
diff --git a/src/backend/utils/adt/pgstatfuncs.c
b/src/backend/utils/adt/pgstatfuncs.c
index adab948..5a1ea49 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -71,12 +71,14 @@ extern Datum
pg_stat_get_db_tuples_fetched(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_inserted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_updated(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_stat_reset_time(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_bgwriter_stat_reset_time(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_buf_fsync_backend(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_buf_alloc(PG_FUNCTION_ARGS);
@@ -1128,6 +1130,24 @@ pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS)
PG_RETURN_INT64(result);
}
+
+Datum
+pg_stat_get_db_stat_reset_time(PG_FUNCTION_ARGS)
+{
+ Oid dbid = PG_GETARG_OID(0);
+ TimestampTz result;
+ PgStat_StatDBEntry *dbentry;
+
+ if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+ result = 0;
+ else
+ result = dbentry->stat_reset_timestamp;
+
+ if (result == 0)
+ PG_RETURN_NULL();
+ else
+ PG_RETURN_TIMESTAMPTZ(result);
+}
Datum
pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS)
@@ -1160,6 +1180,12 @@ pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS)
}
Datum
+pg_stat_get_bgwriter_stat_reset_time(PG_FUNCTION_ARGS)
+{
+ PG_RETURN_TIMESTAMPTZ(pgstat_fetch_global()->stat_reset_timestamp);
+}
+
+Datum
pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(pgstat_fetch_global()->buf_written_backend);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 1e6e75f..14ba954 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -3109,6 +3109,8 @@ DATA(insert OID = 2761 ( pg_stat_get_db_tuples_updated
PGNSP PGUID 12 1 0 0 f f
DESCR("statistics: tuples updated in database");
DATA(insert OID = 2762 ( pg_stat_get_db_tuples_deleted PGNSP PGUID 12 1 0 0 f
f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_tuples_deleted
_null_ _null_ _null_ ));
DESCR("statistics: tuples deleted in database");
+DATA(insert OID = 3116 ( pg_stat_get_db_stat_reset_time PGNSP PGUID 12 1 0 0
f f f t f s 1 0 1184 "26" _null_ _null_ _null_ _null_
pg_stat_get_db_stat_reset_time _null_ _null_ _null_ ));
+DESCR("statistics: last reset for a database");
DATA(insert OID = 2769 ( pg_stat_get_bgwriter_timed_checkpoints PGNSP PGUID 12
1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_
pg_stat_get_bgwriter_timed_checkpoints _null_ _null_ _null_ ));
DESCR("statistics: number of timed checkpoints started by the bgwriter");
DATA(insert OID = 2770 ( pg_stat_get_bgwriter_requested_checkpoints PGNSP
PGUID 12 1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_
pg_stat_get_bgwriter_requested_checkpoints _null_ _null_ _null_ ));
@@ -3119,6 +3121,8 @@ DATA(insert OID = 2772 (
pg_stat_get_bgwriter_buf_written_clean PGNSP PGUID 12 1
DESCR("statistics: number of buffers written by the bgwriter for cleaning
dirty buffers");
DATA(insert OID = 2773 ( pg_stat_get_bgwriter_maxwritten_clean PGNSP PGUID 12
1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_
pg_stat_get_bgwriter_maxwritten_clean _null_ _null_ _null_ ));
DESCR("statistics: number of times the bgwriter stopped processing when it had
written too many buffers while cleaning");
+DATA(insert OID = 3118 ( pg_stat_get_bgwriter_stat_reset_time PGNSP PGUID 12 1
0 0 f f f t f s 0 0 1184 "" _null_ _null_ _null_ _null_
pg_stat_get_bgwriter_stat_reset_time _null_ _null_ _null_ ));
+DESCR("statistics: last reset for the bgwriter");
DATA(insert OID = 2775 ( pg_stat_get_buf_written_backend PGNSP PGUID 12 1 0 0
f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_
pg_stat_get_buf_written_backend _null_ _null_ _null_ ));
DESCR("statistics: number of buffers written by backends");
DATA(insert OID = 3063 ( pg_stat_get_buf_fsync_backend PGNSP PGUID 12 1 0 0 f
f f t f s 0 0 20 "" _null_ _null_ _null_ _null_ pg_stat_get_buf_fsync_backend
_null_ _null_ _null_ ));
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 42bf9c4..9f679b2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_StatDBEntry
PgStat_Counter n_tuples_updated;
PgStat_Counter n_tuples_deleted;
TimestampTz last_autovac_time;
+
+ TimestampTz stat_reset_timestamp;
/*
* tables and functions must be last in the struct, because we don't
write
@@ -565,6 +567,9 @@ typedef struct PgStat_GlobalStats
PgStat_Counter buf_written_backend;
PgStat_Counter buf_fsync_backend;
PgStat_Counter buf_alloc;
+
+ TimestampTz stat_reset_timestamp;
+
} PgStat_GlobalStats;
--
1.7.2.2
--
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