Separate the code to start a new worker into its own function. The code is
exactly the same, modulo whitespace.
This commit is contained in:
Alvaro Herrera
parent
6287eb7adc
commit
a0abe87f1c
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@ -10,7 +10,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.36 2007/03/23 21:23:13 alvherre Exp $
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* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.37 2007/03/23 21:45:17 alvherre Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -118,6 +118,7 @@ static pid_t avworker_forkexec(void);
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NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]);
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NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]);
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static void do_start_worker(void);
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static void do_autovacuum(PgStat_StatDBEntry *dbentry);
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static List *autovac_get_database_list(void);
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static void test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
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@ -218,9 +219,6 @@ NON_EXEC_STATIC void
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AutoVacLauncherMain(int argc, char *argv[])
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{
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sigjmp_buf local_sigjmp_buf;
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List *dblist;
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bool for_xid_wrap;
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autovac_dbase *db;
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MemoryContext avlauncher_cxt;
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/* we are a postmaster subprocess now */
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@ -358,8 +356,6 @@ AutoVacLauncherMain(int argc, char *argv[])
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for (;;)
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{
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TransactionId xidForceLimit;
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ListCell *cell;
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int worker_pid;
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/*
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@ -407,86 +403,8 @@ AutoVacLauncherMain(int argc, char *argv[])
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}
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}
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/* Get a list of databases */
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dblist = autovac_get_database_list();
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do_start_worker();
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/*
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* Determine the oldest datfrozenxid/relfrozenxid that we will allow
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* to pass without forcing a vacuum. (This limit can be tightened for
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* particular tables, but not loosened.)
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*/
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recentXid = ReadNewTransactionId();
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xidForceLimit = recentXid - autovacuum_freeze_max_age;
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/* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
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if (xidForceLimit < FirstNormalTransactionId)
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xidForceLimit -= FirstNormalTransactionId;
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/*
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* Choose a database to connect to. We pick the database that was least
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* recently auto-vacuumed, or one that needs vacuuming to prevent Xid
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* wraparound-related data loss. If any db at risk of wraparound is
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* found, we pick the one with oldest datfrozenxid, independently of
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* autovacuum times.
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*
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* Note that a database with no stats entry is not considered, except for
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* Xid wraparound purposes. The theory is that if no one has ever
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* connected to it since the stats were last initialized, it doesn't need
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* vacuuming.
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*
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* XXX This could be improved if we had more info about whether it needs
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* vacuuming before connecting to it. Perhaps look through the pgstats
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* data for the database's tables? One idea is to keep track of the
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* number of new and dead tuples per database in pgstats. However it
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* isn't clear how to construct a metric that measures that and not cause
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* starvation for less busy databases.
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*/
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db = NULL;
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for_xid_wrap = false;
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foreach(cell, dblist)
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{
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autovac_dbase *tmp = lfirst(cell);
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/* Find pgstat entry if any */
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tmp->entry = pgstat_fetch_stat_dbentry(tmp->oid);
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/* Check to see if this one is at risk of wraparound */
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if (TransactionIdPrecedes(tmp->frozenxid, xidForceLimit))
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{
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if (db == NULL ||
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TransactionIdPrecedes(tmp->frozenxid, db->frozenxid))
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db = tmp;
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for_xid_wrap = true;
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continue;
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}
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else if (for_xid_wrap)
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continue; /* ignore not-at-risk DBs */
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/*
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* Otherwise, skip a database with no pgstat entry; it means it
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* hasn't seen any activity.
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*/
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if (!tmp->entry)
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continue;
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/*
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* Remember the db with oldest autovac time. (If we are here,
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* both tmp->entry and db->entry must be non-null.)
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*/
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if (db == NULL ||
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tmp->entry->last_autovac_time < db->entry->last_autovac_time)
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db = tmp;
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}
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/* Found a database -- process it */
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if (db != NULL)
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{
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LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
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AutoVacuumShmem->process_db = db->oid;
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LWLockRelease(AutovacuumLock);
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SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
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}
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sleep:
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/*
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* in emergency mode, exit immediately so that the postmaster can
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@ -512,6 +430,103 @@ sleep:
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proc_exit(0); /* done */
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}
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/*
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* do_start_worker
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*
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* Bare-bones procedure for starting an autovacuum worker from the launcher.
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* It determines what database to work on, sets up shared memory stuff and
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* signals postmaster to start the worker.
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*/
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static void
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do_start_worker(void)
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{
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List *dblist;
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bool for_xid_wrap;
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autovac_dbase *db;
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ListCell *cell;
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TransactionId xidForceLimit;
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/* Get a list of databases */
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dblist = autovac_get_database_list();
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/*
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* Determine the oldest datfrozenxid/relfrozenxid that we will allow
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* to pass without forcing a vacuum. (This limit can be tightened for
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* particular tables, but not loosened.)
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*/
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recentXid = ReadNewTransactionId();
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xidForceLimit = recentXid - autovacuum_freeze_max_age;
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/* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
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if (xidForceLimit < FirstNormalTransactionId)
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xidForceLimit -= FirstNormalTransactionId;
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/*
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* Choose a database to connect to. We pick the database that was least
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* recently auto-vacuumed, or one that needs vacuuming to prevent Xid
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* wraparound-related data loss. If any db at risk of wraparound is
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* found, we pick the one with oldest datfrozenxid, independently of
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* autovacuum times.
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*
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* Note that a database with no stats entry is not considered, except for
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* Xid wraparound purposes. The theory is that if no one has ever
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* connected to it since the stats were last initialized, it doesn't need
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* vacuuming.
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*
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* XXX This could be improved if we had more info about whether it needs
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* vacuuming before connecting to it. Perhaps look through the pgstats
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* data for the database's tables? One idea is to keep track of the
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* number of new and dead tuples per database in pgstats. However it
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* isn't clear how to construct a metric that measures that and not cause
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* starvation for less busy databases.
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*/
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db = NULL;
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for_xid_wrap = false;
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foreach(cell, dblist)
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{
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autovac_dbase *tmp = lfirst(cell);
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/* Find pgstat entry if any */
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tmp->entry = pgstat_fetch_stat_dbentry(tmp->oid);
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/* Check to see if this one is at risk of wraparound */
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if (TransactionIdPrecedes(tmp->frozenxid, xidForceLimit))
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{
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if (db == NULL ||
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TransactionIdPrecedes(tmp->frozenxid, db->frozenxid))
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db = tmp;
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for_xid_wrap = true;
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continue;
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}
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else if (for_xid_wrap)
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continue; /* ignore not-at-risk DBs */
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/*
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* Otherwise, skip a database with no pgstat entry; it means it
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* hasn't seen any activity.
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*/
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if (!tmp->entry)
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continue;
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/*
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* Remember the db with oldest autovac time. (If we are here,
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* both tmp->entry and db->entry must be non-null.)
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*/
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if (db == NULL ||
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tmp->entry->last_autovac_time < db->entry->last_autovac_time)
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db = tmp;
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}
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/* Found a database -- process it */
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if (db != NULL)
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{
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LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
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AutoVacuumShmem->process_db = db->oid;
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LWLockRelease(AutovacuumLock);
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SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
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}
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}
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/* SIGHUP: set flag to re-read config file at next convenient time */
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static void
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avl_sighup_handler(SIGNAL_ARGS)
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