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Take the statistics collector out of the loop for monitoring backends'
current commands; instead, store current-status information in shared memory. This substantially reduces the overhead of stats_command_string and also ensures that pg_stat_activity is fully up to date at all times. Per my recent proposal.
This commit is contained in:
Tom Lane
@ -5,7 +5,7 @@
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*
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* Copyright (c) 2001-2006, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/include/pgstat.h,v 1.46 2006/05/30 02:35:39 momjian Exp $
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* $PostgreSQL: pgsql/src/include/pgstat.h,v 1.47 2006/06/19 01:51:21 tgl Exp $
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* ----------
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*/
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#ifndef PGSTAT_H
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@ -16,16 +16,14 @@
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#include "utils/rel.h"
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#include "utils/timestamp.h"
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/* ----------
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* The types of backend/postmaster -> collector messages
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* The types of backend -> collector messages
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* ----------
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*/
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typedef enum StatMsgType
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{
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PGSTAT_MTYPE_DUMMY,
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PGSTAT_MTYPE_BESTART,
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PGSTAT_MTYPE_BETERM,
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PGSTAT_MTYPE_ACTIVITY,
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PGSTAT_MTYPE_TABSTAT,
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PGSTAT_MTYPE_TABPURGE,
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PGSTAT_MTYPE_DROPDB,
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@ -56,8 +54,6 @@ typedef struct PgStat_MsgHdr
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{
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StatMsgType m_type;
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int m_size;
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int m_backendid;
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int m_procpid;
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} PgStat_MsgHdr;
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/* ----------
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@ -68,6 +64,17 @@ typedef struct PgStat_MsgHdr
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*/
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#define PGSTAT_MSG_PAYLOAD (1000 - sizeof(PgStat_MsgHdr))
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/* ----------
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* PgStat_MsgDummy A dummy message, ignored by the collector
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* ----------
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*/
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typedef struct PgStat_MsgDummy
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{
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PgStat_MsgHdr m_hdr;
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} PgStat_MsgDummy;
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/* ----------
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* PgStat_TableEntry Per-table info in a MsgTabstat
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*
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@ -96,96 +103,6 @@ typedef struct PgStat_TableEntry
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PgStat_Counter t_blocks_hit;
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} PgStat_TableEntry;
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/* ----------
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* PgStat_MsgDummy A dummy message, ignored by the collector
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* ----------
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*/
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typedef struct PgStat_MsgDummy
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{
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PgStat_MsgHdr m_hdr;
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char m_dummy[512];
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} PgStat_MsgDummy;
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/* ----------
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* PgStat_MsgBestart Sent by the backend on startup
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* ----------
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*/
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typedef struct PgStat_MsgBestart
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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Oid m_userid;
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SockAddr m_clientaddr;
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} PgStat_MsgBestart;
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/* ----------
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* PgStat_MsgBeterm Sent by the postmaster after backend exit
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* ----------
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*/
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typedef struct PgStat_MsgBeterm
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{
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PgStat_MsgHdr m_hdr;
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} PgStat_MsgBeterm;
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/* ----------
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* PgStat_MsgAutovacStart Sent by the autovacuum daemon to signal
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* that a database is going to be processed
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* ----------
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*/
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typedef struct PgStat_MsgAutovacStart
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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TimestampTz m_start_time;
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} PgStat_MsgAutovacStart;
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/* ----------
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* PgStat_MsgVacuum Sent by the backend or autovacuum daemon
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* after VACUUM or VACUUM ANALYZE
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* ----------
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*/
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typedef struct PgStat_MsgVacuum
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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Oid m_tableoid;
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bool m_analyze;
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bool m_autovacuum;
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TimestampTz m_vacuumtime;
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PgStat_Counter m_tuples;
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} PgStat_MsgVacuum;
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/* ----------
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* PgStat_MsgAnalyze Sent by the backend or autovacuum daemon
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* after ANALYZE
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* ----------
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*/
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typedef struct PgStat_MsgAnalyze
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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Oid m_tableoid;
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bool m_autovacuum;
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TimestampTz m_analyzetime;
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PgStat_Counter m_live_tuples;
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PgStat_Counter m_dead_tuples;
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} PgStat_MsgAnalyze;
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/* ----------
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* PgStat_MsgActivity Sent by the backends when they start
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* to parse a query.
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* ----------
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*/
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#define PGSTAT_ACTIVITY_SIZE PGSTAT_MSG_PAYLOAD
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typedef struct PgStat_MsgActivity
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{
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PgStat_MsgHdr m_hdr;
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char m_cmd_str[PGSTAT_ACTIVITY_SIZE];
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} PgStat_MsgActivity;
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/* ----------
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* PgStat_MsgTabstat Sent by the backend to report table
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* and buffer access statistics.
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@ -205,6 +122,7 @@ typedef struct PgStat_MsgTabstat
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PgStat_TableEntry m_entry[PGSTAT_NUM_TABENTRIES];
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} PgStat_MsgTabstat;
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/* ----------
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* PgStat_MsgTabpurge Sent by the backend to tell the collector
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* about dead tables.
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@ -247,6 +165,53 @@ typedef struct PgStat_MsgResetcounter
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} PgStat_MsgResetcounter;
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/* ----------
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* PgStat_MsgAutovacStart Sent by the autovacuum daemon to signal
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* that a database is going to be processed
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* ----------
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*/
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typedef struct PgStat_MsgAutovacStart
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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TimestampTz m_start_time;
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} PgStat_MsgAutovacStart;
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/* ----------
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* PgStat_MsgVacuum Sent by the backend or autovacuum daemon
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* after VACUUM or VACUUM ANALYZE
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* ----------
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*/
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typedef struct PgStat_MsgVacuum
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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Oid m_tableoid;
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bool m_analyze;
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bool m_autovacuum;
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TimestampTz m_vacuumtime;
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PgStat_Counter m_tuples;
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} PgStat_MsgVacuum;
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/* ----------
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* PgStat_MsgAnalyze Sent by the backend or autovacuum daemon
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* after ANALYZE
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* ----------
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*/
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typedef struct PgStat_MsgAnalyze
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{
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PgStat_MsgHdr m_hdr;
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Oid m_databaseid;
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Oid m_tableoid;
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bool m_autovacuum;
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TimestampTz m_analyzetime;
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PgStat_Counter m_live_tuples;
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PgStat_Counter m_dead_tuples;
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} PgStat_MsgAnalyze;
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/* ----------
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* PgStat_Msg Union over all possible messages.
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* ----------
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@ -255,8 +220,6 @@ typedef union PgStat_Msg
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{
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PgStat_MsgHdr msg_hdr;
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PgStat_MsgDummy msg_dummy;
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PgStat_MsgBestart msg_bestart;
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PgStat_MsgActivity msg_activity;
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PgStat_MsgTabstat msg_tabstat;
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PgStat_MsgTabpurge msg_tabpurge;
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PgStat_MsgDropdb msg_dropdb;
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@ -275,19 +238,15 @@ typedef union PgStat_Msg
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* ------------------------------------------------------------
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*/
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#define PGSTAT_FILE_FORMAT_ID 0x01A5BC95
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#define PGSTAT_FILE_FORMAT_ID 0x01A5BC96
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/* ----------
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* PgStat_StatDBEntry The collector's data per database
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*
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* Note: n_backends is not maintained within the collector. It's computed
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* when a backend reads the stats file for use.
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* ----------
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*/
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typedef struct PgStat_StatDBEntry
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{
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Oid databaseid;
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int n_backends;
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PgStat_Counter n_xact_commit;
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PgStat_Counter n_xact_rollback;
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PgStat_Counter n_blocks_fetched;
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@ -302,35 +261,6 @@ typedef struct PgStat_StatDBEntry
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} PgStat_StatDBEntry;
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/* ----------
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* PgStat_StatBeEntry The collector's data per backend
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* ----------
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*/
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typedef struct PgStat_StatBeEntry
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{
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/* An entry is non-empty iff procpid > 0 */
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int procpid;
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TimestampTz start_timestamp;
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TimestampTz activity_start_timestamp;
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/*
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* These fields are initialized by the BESTART message. If we have
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* received messages from a backend before we have received its BESTART,
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* these fields will be uninitialized: userid and databaseid will be
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* InvalidOid, and clientaddr will be undefined.
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*/
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Oid userid;
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Oid databaseid;
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SockAddr clientaddr;
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/*
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* activity[] must be last in the struct, because we only write as much
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* of it as needed to the stats file.
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*/
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char activity[PGSTAT_ACTIVITY_SIZE];
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} PgStat_StatBeEntry;
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/* ----------
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* PgStat_StatTabEntry The collector's data per table (or index)
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* ----------
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@ -338,10 +268,6 @@ typedef struct PgStat_StatBeEntry
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typedef struct PgStat_StatTabEntry
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{
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Oid tableid;
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TimestampTz vacuum_timestamp; /* user initiated vacuum */
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TimestampTz autovac_vacuum_timestamp; /* autovacuum initiated */
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TimestampTz analyze_timestamp; /* user initiated */
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TimestampTz autovac_analyze_timestamp; /* autovacuum initiated */
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PgStat_Counter numscans;
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@ -358,27 +284,81 @@ typedef struct PgStat_StatTabEntry
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PgStat_Counter blocks_fetched;
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PgStat_Counter blocks_hit;
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TimestampTz vacuum_timestamp; /* user initiated vacuum */
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TimestampTz autovac_vacuum_timestamp; /* autovacuum initiated */
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TimestampTz analyze_timestamp; /* user initiated */
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TimestampTz autovac_analyze_timestamp; /* autovacuum initiated */
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} PgStat_StatTabEntry;
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/* ----------
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* Shared-memory data structures
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* ----------
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*/
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/* Max length of st_activity string ... perhaps replace with a GUC var? */
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#define PGBE_ACTIVITY_SIZE 1024
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/* ----------
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* PgBackendStatus
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*
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* Each live backend maintains a PgBackendStatus struct in shared memory
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* showing its current activity. (The structs are allocated according to
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* BackendId, but that is not critical.) Note that the collector process
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* has no involvement in, or even access to, these structs.
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* ----------
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*/
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typedef struct PgBackendStatus
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{
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/*
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* To avoid locking overhead, we use the following protocol: a backend
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* increments st_changecount before modifying its entry, and again after
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* finishing a modification. A would-be reader should note the value
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* of st_changecount, copy the entry into private memory, then check
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* st_changecount again. If the value hasn't changed, and if it's even,
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* the copy is valid; otherwise start over. This makes updates cheap
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* while reads are potentially expensive, but that's the tradeoff we want.
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*/
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int st_changecount;
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/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
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int st_procpid;
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/* Times of backend process start and current activity start */
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TimestampTz st_proc_start_timestamp;
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TimestampTz st_activity_start_timestamp;
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/* Database OID, owning user's OID, connection client address */
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Oid st_databaseid;
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Oid st_userid;
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SockAddr st_clientaddr;
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/* current command string; MUST be null-terminated */
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char st_activity[PGBE_ACTIVITY_SIZE];
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} PgBackendStatus;
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/* ----------
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* GUC parameters
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* ----------
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*/
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extern bool pgstat_collect_startcollector;
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extern bool pgstat_collect_resetonpmstart;
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extern bool pgstat_collect_querystring;
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extern bool pgstat_collect_tuplelevel;
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extern bool pgstat_collect_blocklevel;
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extern bool pgstat_collect_querystring;
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/* ----------
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* Functions called from postmaster
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* ----------
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*/
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extern Size BackendStatusShmemSize(void);
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extern void CreateSharedBackendStatus(void);
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extern void pgstat_init(void);
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extern int pgstat_start(void);
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extern void pgstat_beterm(int pid);
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extern void pgstat_reset_all(void);
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#ifdef EXEC_BACKEND
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@ -391,21 +371,23 @@ extern void PgstatCollectorMain(int argc, char *argv[]);
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* Functions called from backends
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* ----------
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*/
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extern void pgstat_bestart(void);
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extern void pgstat_ping(void);
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extern void pgstat_report_activity(const char *what);
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extern void pgstat_report_tabstat(void);
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extern void pgstat_vacuum_tabstat(void);
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extern void pgstat_drop_relation(Oid relid);
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extern void pgstat_reset_counters(void);
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extern void pgstat_report_autovac(Oid dboid);
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extern void pgstat_report_vacuum(Oid tableoid, bool shared,
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bool analyze, PgStat_Counter tuples);
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extern void pgstat_report_analyze(Oid tableoid, bool shared,
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PgStat_Counter livetuples,
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PgStat_Counter deadtuples);
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extern void pgstat_vacuum_tabstat(void);
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extern void pgstat_drop_relation(Oid relid);
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extern void pgstat_reset_counters(void);
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extern void pgstat_bestart(void);
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extern void pgstat_report_activity(const char *what);
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extern void pgstat_initstats(PgStat_Info *stats, Relation rel);
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@ -492,7 +474,7 @@ extern void pgstat_count_xact_rollback(void);
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*/
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extern PgStat_StatDBEntry *pgstat_fetch_stat_dbentry(Oid dbid);
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extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
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extern PgStat_StatBeEntry *pgstat_fetch_stat_beentry(int beid);
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extern PgBackendStatus *pgstat_fetch_stat_beentry(int beid);
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extern int pgstat_fetch_stat_numbackends(void);
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#endif /* PGSTAT_H */
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Reference in New Issue
Block a user