/*------------------------------------------------------------------------- * * autovacuum.c * * PostgreSQL Integrated Autovacuum Daemon * * * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.40 2007/03/28 22:17:12 alvherre Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include #include #include "access/genam.h" #include "access/heapam.h" #include "access/transam.h" #include "access/xact.h" #include "catalog/indexing.h" #include "catalog/namespace.h" #include "catalog/pg_autovacuum.h" #include "catalog/pg_database.h" #include "commands/vacuum.h" #include "libpq/hba.h" #include "libpq/pqsignal.h" #include "miscadmin.h" #include "pgstat.h" #include "postmaster/autovacuum.h" #include "postmaster/fork_process.h" #include "postmaster/postmaster.h" #include "storage/fd.h" #include "storage/ipc.h" #include "storage/pmsignal.h" #include "storage/proc.h" #include "storage/procarray.h" #include "storage/sinval.h" #include "tcop/tcopprot.h" #include "utils/flatfiles.h" #include "utils/fmgroids.h" #include "utils/lsyscache.h" #include "utils/memutils.h" #include "utils/ps_status.h" #include "utils/syscache.h" static volatile sig_atomic_t got_SIGHUP = false; static volatile sig_atomic_t avlauncher_shutdown_request = false; /* * GUC parameters */ bool autovacuum_start_daemon = false; int autovacuum_naptime; int autovacuum_vac_thresh; double autovacuum_vac_scale; int autovacuum_anl_thresh; double autovacuum_anl_scale; int autovacuum_freeze_max_age; int autovacuum_vac_cost_delay; int autovacuum_vac_cost_limit; /* Flag to tell if we are in the autovacuum daemon process */ static bool am_autovacuum_launcher = false; static bool am_autovacuum_worker = false; /* Comparison point for determining whether freeze_max_age is exceeded */ static TransactionId recentXid; /* Default freeze_min_age to use for autovacuum (varies by database) */ static int default_freeze_min_age; /* Memory context for long-lived data */ static MemoryContext AutovacMemCxt; /* struct to keep list of candidate databases for vacuum */ typedef struct autovac_dbase { Oid ad_datid; char *ad_name; TransactionId ad_frozenxid; PgStat_StatDBEntry *ad_entry; } autovac_dbase; /* struct to keep track of tables to vacuum and/or analyze, in 1st pass */ typedef struct av_relation { Oid ar_relid; Oid ar_toastrelid; } av_relation; /* struct to keep track of tables to vacuum and/or analyze, after rechecking */ typedef struct autovac_table { Oid at_relid; Oid at_toastrelid; bool at_dovacuum; bool at_doanalyze; int at_freeze_min_age; int at_vacuum_cost_delay; int at_vacuum_cost_limit; } autovac_table; typedef struct { Oid process_db; /* OID of database to process */ int worker_pid; /* PID of the worker process, if any */ } AutoVacuumShmemStruct; static AutoVacuumShmemStruct *AutoVacuumShmem; #ifdef EXEC_BACKEND static pid_t avlauncher_forkexec(void); static pid_t avworker_forkexec(void); #endif NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]); NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]); static void do_start_worker(void); static void do_autovacuum(void); static List *autovac_get_database_list(void); static void relation_check_autovac(Oid relid, Form_pg_class classForm, Form_pg_autovacuum avForm, PgStat_StatTabEntry *tabentry, List **table_oids, List **table_toast_list, List **toast_oids); static autovac_table *table_recheck_autovac(Oid relid); static void relation_needs_vacanalyze(Oid relid, Form_pg_autovacuum avForm, Form_pg_class classForm, PgStat_StatTabEntry *tabentry, bool *dovacuum, bool *doanalyze); static void autovacuum_do_vac_analyze(Oid relid, bool dovacuum, bool doanalyze, int freeze_min_age); static HeapTuple get_pg_autovacuum_tuple_relid(Relation avRel, Oid relid); static PgStat_StatTabEntry *get_pgstat_tabentry_relid(Oid relid, bool isshared, PgStat_StatDBEntry *shared, PgStat_StatDBEntry *dbentry); static void autovac_report_activity(VacuumStmt *vacstmt, Oid relid); static void avl_sighup_handler(SIGNAL_ARGS); static void avlauncher_shutdown(SIGNAL_ARGS); static void avl_quickdie(SIGNAL_ARGS); /******************************************************************** * AUTOVACUUM LAUNCHER CODE ********************************************************************/ #ifdef EXEC_BACKEND /* * forkexec routine for the autovacuum launcher process. * * Format up the arglist, then fork and exec. */ static pid_t avlauncher_forkexec(void) { char *av[10]; int ac = 0; av[ac++] = "postgres"; av[ac++] = "--forkavlauncher"; av[ac++] = NULL; /* filled in by postmaster_forkexec */ av[ac] = NULL; Assert(ac < lengthof(av)); return postmaster_forkexec(ac, av); } /* * We need this set from the outside, before InitProcess is called */ void AutovacuumLauncherIAm(void) { am_autovacuum_launcher = true; } #endif /* * Main entry point for autovacuum launcher process, to be called from the * postmaster. */ int StartAutoVacLauncher(void) { pid_t AutoVacPID; #ifdef EXEC_BACKEND switch ((AutoVacPID = avlauncher_forkexec())) #else switch ((AutoVacPID = fork_process())) #endif { case -1: ereport(LOG, (errmsg("could not fork autovacuum process: %m"))); return 0; #ifndef EXEC_BACKEND case 0: /* in postmaster child ... */ /* Close the postmaster's sockets */ ClosePostmasterPorts(false); /* Lose the postmaster's on-exit routines */ on_exit_reset(); AutoVacLauncherMain(0, NULL); break; #endif default: return (int) AutoVacPID; } /* shouldn't get here */ return 0; } /* * Main loop for the autovacuum launcher process. */ NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) { sigjmp_buf local_sigjmp_buf; MemoryContext avlauncher_cxt; /* we are a postmaster subprocess now */ IsUnderPostmaster = true; am_autovacuum_launcher = true; /* reset MyProcPid */ MyProcPid = getpid(); /* Identify myself via ps */ init_ps_display("autovacuum launcher process", "", "", ""); SetProcessingMode(InitProcessing); /* * If possible, make this process a group leader, so that the postmaster * can signal any child processes too. (autovacuum probably never has * any child processes, but for consistency we make all postmaster * child processes do this.) */ #ifdef HAVE_SETSID if (setsid() < 0) elog(FATAL, "setsid() failed: %m"); #endif /* * Set up signal handlers. Since this is an auxiliary process, it has * particular signal requirements -- no deadlock checker or sinval * catchup, for example. * * XXX It may be a good idea to receive signals when an avworker process * finishes. */ pqsignal(SIGHUP, avl_sighup_handler); pqsignal(SIGINT, SIG_IGN); pqsignal(SIGTERM, avlauncher_shutdown); pqsignal(SIGQUIT, avl_quickdie); pqsignal(SIGALRM, SIG_IGN); pqsignal(SIGPIPE, SIG_IGN); pqsignal(SIGUSR1, SIG_IGN); /* We don't listen for async notifies */ pqsignal(SIGUSR2, SIG_IGN); pqsignal(SIGFPE, FloatExceptionHandler); pqsignal(SIGCHLD, SIG_DFL); /* Early initialization */ BaseInit(); /* * Create a per-backend PGPROC struct in shared memory, except in the * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do * this before we can use LWLocks (and in the EXEC_BACKEND case we already * had to do some stuff with LWLocks). */ #ifndef EXEC_BACKEND InitAuxiliaryProcess(); #endif /* * Create a memory context that we will do all our work in. We do this so * that we can reset the context during error recovery and thereby avoid * possible memory leaks. */ avlauncher_cxt = AllocSetContextCreate(TopMemoryContext, "Autovacuum Launcher", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); MemoryContextSwitchTo(avlauncher_cxt); /* * If an exception is encountered, processing resumes here. * * This code is heavily based on bgwriter.c, q.v. */ if (sigsetjmp(local_sigjmp_buf, 1) != 0) { /* since not using PG_TRY, must reset error stack by hand */ error_context_stack = NULL; /* Prevents interrupts while cleaning up */ HOLD_INTERRUPTS(); /* Report the error to the server log */ EmitErrorReport(); /* * These operations are really just a minimal subset of * AbortTransaction(). We don't have very many resources to worry * about, but we do have LWLocks. */ LWLockReleaseAll(); AtEOXact_Files(); /* * Now return to normal top-level context and clear ErrorContext for * next time. */ MemoryContextSwitchTo(avlauncher_cxt); FlushErrorState(); /* Flush any leaked data in the top-level context */ MemoryContextResetAndDeleteChildren(avlauncher_cxt); /* Make sure pgstat also considers our stat data as gone */ pgstat_clear_snapshot(); /* Now we can allow interrupts again */ RESUME_INTERRUPTS(); /* * Sleep at least 1 second after any error. We don't want to be * filling the error logs as fast as we can. */ pg_usleep(1000000L); } /* We can now handle ereport(ERROR) */ PG_exception_stack = &local_sigjmp_buf; ereport(LOG, (errmsg("autovacuum launcher started"))); PG_SETMASK(&UnBlockSig); /* * take a nap before executing the first iteration, unless we were * requested an emergency run. */ if (autovacuum_start_daemon) pg_usleep(autovacuum_naptime * 1000000L); for (;;) { int worker_pid; /* * Emergency bailout if postmaster has died. This is to avoid the * necessity for manual cleanup of all postmaster children. */ if (!PostmasterIsAlive(true)) exit(1); if (avlauncher_shutdown_request) break; if (got_SIGHUP) { got_SIGHUP = false; ProcessConfigFile(PGC_SIGHUP); } /* * if there's a worker already running, sleep until it * disappears. */ LWLockAcquire(AutovacuumLock, LW_SHARED); worker_pid = AutoVacuumShmem->worker_pid; LWLockRelease(AutovacuumLock); if (worker_pid != 0) { PGPROC *proc = BackendPidGetProc(worker_pid); if (proc != NULL && proc->isAutovacuum) goto sleep; else { /* * if the worker is not really running (or it's a process * that's not an autovacuum worker), remove the PID from shmem. * This should not happen, because either the worker exits * cleanly, in which case it'll remove the PID, or it dies, in * which case postmaster will cause a system reset cycle. */ LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE); worker_pid = 0; LWLockRelease(AutovacuumLock); } } do_start_worker(); sleep: /* * in emergency mode, exit immediately so that the postmaster can * request another run right away if needed. * * XXX -- maybe it would be better to handle this inside the launcher * itself. */ if (!autovacuum_start_daemon) break; /* have pgstat read the file again next time */ pgstat_clear_snapshot(); /* now sleep until the next autovac iteration */ pg_usleep(autovacuum_naptime * 1000000L); } /* Normal exit from the autovac launcher is here */ ereport(LOG, (errmsg("autovacuum launcher shutting down"))); proc_exit(0); /* done */ } /* * do_start_worker * * Bare-bones procedure for starting an autovacuum worker from the launcher. * It determines what database to work on, sets up shared memory stuff and * signals postmaster to start the worker. */ static void do_start_worker(void) { List *dblist; bool for_xid_wrap; autovac_dbase *db; ListCell *cell; TransactionId xidForceLimit; /* Get a list of databases */ dblist = autovac_get_database_list(); /* * Determine the oldest datfrozenxid/relfrozenxid that we will allow * to pass without forcing a vacuum. (This limit can be tightened for * particular tables, but not loosened.) */ recentXid = ReadNewTransactionId(); xidForceLimit = recentXid - autovacuum_freeze_max_age; /* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */ if (xidForceLimit < FirstNormalTransactionId) xidForceLimit -= FirstNormalTransactionId; /* * Choose a database to connect to. We pick the database that was least * recently auto-vacuumed, or one that needs vacuuming to prevent Xid * wraparound-related data loss. If any db at risk of wraparound is * found, we pick the one with oldest datfrozenxid, independently of * autovacuum times. * * Note that a database with no stats entry is not considered, except for * Xid wraparound purposes. The theory is that if no one has ever * connected to it since the stats were last initialized, it doesn't need * vacuuming. * * XXX This could be improved if we had more info about whether it needs * vacuuming before connecting to it. Perhaps look through the pgstats * data for the database's tables? One idea is to keep track of the * number of new and dead tuples per database in pgstats. However it * isn't clear how to construct a metric that measures that and not cause * starvation for less busy databases. */ db = NULL; for_xid_wrap = false; foreach(cell, dblist) { autovac_dbase *tmp = lfirst(cell); /* Find pgstat entry if any */ tmp->ad_entry = pgstat_fetch_stat_dbentry(tmp->ad_datid); /* Check to see if this one is at risk of wraparound */ if (TransactionIdPrecedes(tmp->ad_frozenxid, xidForceLimit)) { if (db == NULL || TransactionIdPrecedes(tmp->ad_frozenxid, db->ad_frozenxid)) db = tmp; for_xid_wrap = true; continue; } else if (for_xid_wrap) continue; /* ignore not-at-risk DBs */ /* * Otherwise, skip a database with no pgstat entry; it means it * hasn't seen any activity. */ if (!tmp->ad_entry) continue; /* * Remember the db with oldest autovac time. (If we are here, * both tmp->entry and db->entry must be non-null.) */ if (db == NULL || tmp->ad_entry->last_autovac_time < db->ad_entry->last_autovac_time) db = tmp; } /* Found a database -- process it */ if (db != NULL) { LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE); AutoVacuumShmem->process_db = db->ad_datid; LWLockRelease(AutovacuumLock); SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER); } } /* SIGHUP: set flag to re-read config file at next convenient time */ static void avl_sighup_handler(SIGNAL_ARGS) { got_SIGHUP = true; } static void avlauncher_shutdown(SIGNAL_ARGS) { avlauncher_shutdown_request = true; } /* * avl_quickdie occurs when signalled SIGQUIT from postmaster. * * Some backend has bought the farm, so we need to stop what we're doing * and exit. */ static void avl_quickdie(SIGNAL_ARGS) { PG_SETMASK(&BlockSig); /* * DO NOT proc_exit() -- we're here because shared memory may be * corrupted, so we don't want to try to clean up our transaction. Just * nail the windows shut and get out of town. * * Note we do exit(2) not exit(0). This is to force the postmaster into a * system reset cycle if some idiot DBA sends a manual SIGQUIT to a random * backend. This is necessary precisely because we don't clean up our * shared memory state. */ exit(2); } /******************************************************************** * AUTOVACUUM WORKER CODE ********************************************************************/ #ifdef EXEC_BACKEND /* * forkexec routines for the autovacuum worker. * * Format up the arglist, then fork and exec. */ static pid_t avworker_forkexec(void) { char *av[10]; int ac = 0; av[ac++] = "postgres"; av[ac++] = "--forkavworker"; av[ac++] = NULL; /* filled in by postmaster_forkexec */ av[ac] = NULL; Assert(ac < lengthof(av)); return postmaster_forkexec(ac, av); } /* * We need this set from the outside, before InitProcess is called */ void AutovacuumWorkerIAm(void) { am_autovacuum_worker = true; } #endif /* * Main entry point for autovacuum worker process. * * This code is heavily based on pgarch.c, q.v. */ int StartAutoVacWorker(void) { pid_t worker_pid; #ifdef EXEC_BACKEND switch ((worker_pid = avworker_forkexec())) #else switch ((worker_pid = fork_process())) #endif { case -1: ereport(LOG, (errmsg("could not fork autovacuum process: %m"))); return 0; #ifndef EXEC_BACKEND case 0: /* in postmaster child ... */ /* Close the postmaster's sockets */ ClosePostmasterPorts(false); /* Lose the postmaster's on-exit routines */ on_exit_reset(); AutoVacWorkerMain(0, NULL); break; #endif default: return (int) worker_pid; } /* shouldn't get here */ return 0; } /* * AutoVacWorkerMain */ NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]) { sigjmp_buf local_sigjmp_buf; Oid dbid; /* we are a postmaster subprocess now */ IsUnderPostmaster = true; am_autovacuum_worker = true; /* reset MyProcPid */ MyProcPid = getpid(); /* Identify myself via ps */ init_ps_display("autovacuum worker process", "", "", ""); SetProcessingMode(InitProcessing); /* * If possible, make this process a group leader, so that the postmaster * can signal any child processes too. (autovacuum probably never has * any child processes, but for consistency we make all postmaster * child processes do this.) */ #ifdef HAVE_SETSID if (setsid() < 0) elog(FATAL, "setsid() failed: %m"); #endif /* * Set up signal handlers. We operate on databases much like a regular * backend, so we use the same signal handling. See equivalent code in * tcop/postgres.c. * * Currently, we don't pay attention to postgresql.conf changes that * happen during a single daemon iteration, so we can ignore SIGHUP. */ pqsignal(SIGHUP, SIG_IGN); /* * Presently, SIGINT will lead to autovacuum shutdown, because that's how * we handle ereport(ERROR). It could be improved however. */ pqsignal(SIGINT, StatementCancelHandler); pqsignal(SIGTERM, die); pqsignal(SIGQUIT, quickdie); pqsignal(SIGALRM, handle_sig_alarm); pqsignal(SIGPIPE, SIG_IGN); pqsignal(SIGUSR1, CatchupInterruptHandler); /* We don't listen for async notifies */ pqsignal(SIGUSR2, SIG_IGN); pqsignal(SIGFPE, FloatExceptionHandler); pqsignal(SIGCHLD, SIG_DFL); /* Early initialization */ BaseInit(); /* * Create a per-backend PGPROC struct in shared memory, except in the * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do * this before we can use LWLocks (and in the EXEC_BACKEND case we already * had to do some stuff with LWLocks). */ #ifndef EXEC_BACKEND InitProcess(); #endif /* * If an exception is encountered, processing resumes here. * * See notes in postgres.c about the design of this coding. */ if (sigsetjmp(local_sigjmp_buf, 1) != 0) { /* Prevents interrupts while cleaning up */ HOLD_INTERRUPTS(); /* Report the error to the server log */ EmitErrorReport(); /* * We can now go away. Note that because we called InitProcess, a * callback was registered to do ProcKill, which will clean up * necessary state. */ proc_exit(0); } /* We can now handle ereport(ERROR) */ PG_exception_stack = &local_sigjmp_buf; PG_SETMASK(&UnBlockSig); /* * Force zero_damaged_pages OFF in the autovac process, even if it is set * in postgresql.conf. We don't really want such a dangerous option being * applied non-interactively. */ SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE); /* * Get the database Id we're going to work on, and announce our PID * in the shared memory area. We remove the database OID immediately * from the shared memory area. */ LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE); dbid = AutoVacuumShmem->process_db; AutoVacuumShmem->process_db = InvalidOid; AutoVacuumShmem->worker_pid = MyProcPid; LWLockRelease(AutovacuumLock); if (OidIsValid(dbid)) { char *dbname; /* * Report autovac startup to the stats collector. We deliberately do * this before InitPostgres, so that the last_autovac_time will get * updated even if the connection attempt fails. This is to prevent * autovac from getting "stuck" repeatedly selecting an unopenable * database, rather than making any progress on stuff it can connect * to. */ pgstat_report_autovac(dbid); /* * Connect to the selected database * * Note: if we have selected a just-deleted database (due to using * stale stats info), we'll fail and exit here. */ InitPostgres(NULL, dbid, NULL, &dbname); SetProcessingMode(NormalProcessing); set_ps_display(dbname, false); ereport(DEBUG1, (errmsg("autovacuum: processing database \"%s\"", dbname))); /* Create the memory context where cross-transaction state is stored */ AutovacMemCxt = AllocSetContextCreate(TopMemoryContext, "Autovacuum context", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); /* And do an appropriate amount of work */ recentXid = ReadNewTransactionId(); do_autovacuum(); } /* * Now remove our PID from shared memory, so that the launcher can start * another worker as soon as appropriate. */ LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE); AutoVacuumShmem->worker_pid = 0; LWLockRelease(AutovacuumLock); /* All done, go away */ proc_exit(0); } /* * autovac_get_database_list * * Return a list of all databases. Note we cannot use pg_database, * because we aren't connected; we use the flat database file. */ static List * autovac_get_database_list(void) { char *filename; List *dblist = NIL; char thisname[NAMEDATALEN]; FILE *db_file; Oid db_id; Oid db_tablespace; TransactionId db_frozenxid; filename = database_getflatfilename(); db_file = AllocateFile(filename, "r"); if (db_file == NULL) ereport(FATAL, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", filename))); while (read_pg_database_line(db_file, thisname, &db_id, &db_tablespace, &db_frozenxid)) { autovac_dbase *avdb; avdb = (autovac_dbase *) palloc(sizeof(autovac_dbase)); avdb->ad_datid = db_id; avdb->ad_name = pstrdup(thisname); avdb->ad_frozenxid = db_frozenxid; /* this gets set later: */ avdb->ad_entry = NULL; dblist = lappend(dblist, avdb); } FreeFile(db_file); pfree(filename); return dblist; } /* * Process a database table-by-table * * Note that CHECK_FOR_INTERRUPTS is supposed to be used in certain spots in * order not to ignore shutdown commands for too long. */ static void do_autovacuum(void) { Relation classRel, avRel; HeapTuple tuple; HeapScanDesc relScan; Form_pg_database dbForm; List *table_oids = NIL; List *toast_oids = NIL; List *table_toast_list = NIL; ListCell *cell; PgStat_StatDBEntry *shared; PgStat_StatDBEntry *dbentry; /* * may be NULL if we couldn't find an entry (only happens if we * are forcing a vacuum for anti-wrap purposes). */ dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId); /* Start a transaction so our commands have one to play into. */ StartTransactionCommand(); /* functions in indexes may want a snapshot set */ ActiveSnapshot = CopySnapshot(GetTransactionSnapshot()); /* * Clean up any dead statistics collector entries for this DB. We always * want to do this exactly once per DB-processing cycle, even if we find * nothing worth vacuuming in the database. */ pgstat_vacuum_tabstat(); /* * Find the pg_database entry and select the default freeze_min_age. * We use zero in template and nonconnectable databases, * else the system-wide default. */ tuple = SearchSysCache(DATABASEOID, ObjectIdGetDatum(MyDatabaseId), 0, 0, 0); if (!HeapTupleIsValid(tuple)) elog(ERROR, "cache lookup failed for database %u", MyDatabaseId); dbForm = (Form_pg_database) GETSTRUCT(tuple); if (dbForm->datistemplate || !dbForm->datallowconn) default_freeze_min_age = 0; else default_freeze_min_age = vacuum_freeze_min_age; ReleaseSysCache(tuple); /* * StartTransactionCommand and CommitTransactionCommand will automatically * switch to other contexts. We need this one to keep the list of * relations to vacuum/analyze across transactions. */ MemoryContextSwitchTo(AutovacMemCxt); /* The database hash where pgstat keeps shared relations */ shared = pgstat_fetch_stat_dbentry(InvalidOid); classRel = heap_open(RelationRelationId, AccessShareLock); avRel = heap_open(AutovacuumRelationId, AccessShareLock); /* * Scan pg_class and determine which tables to vacuum. * * The stats subsystem collects stats for toast tables independently of * the stats for their parent tables. We need to check those stats since * in cases with short, wide tables there might be proportionally much * more activity in the toast table than in its parent. * * Since we can only issue VACUUM against the parent table, we need to * transpose a decision to vacuum a toast table into a decision to vacuum * its parent. There's no point in considering ANALYZE on a toast table, * either. To support this, we keep a list of OIDs of toast tables that * need vacuuming alongside the list of regular tables. Regular tables * will be entered into the table list even if they appear not to need * vacuuming; we go back and re-mark them after finding all the vacuumable * toast tables. */ relScan = heap_beginscan(classRel, SnapshotNow, 0, NULL); while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL) { Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple); Form_pg_autovacuum avForm = NULL; PgStat_StatTabEntry *tabentry; HeapTuple avTup; Oid relid; /* Consider only regular and toast tables. */ if (classForm->relkind != RELKIND_RELATION && classForm->relkind != RELKIND_TOASTVALUE) continue; /* * Skip temp tables (i.e. those in temp namespaces). We cannot safely * process other backends' temp tables. */ if (isAnyTempNamespace(classForm->relnamespace)) continue; relid = HeapTupleGetOid(tuple); /* Fetch the pg_autovacuum tuple for the relation, if any */ avTup = get_pg_autovacuum_tuple_relid(avRel, relid); if (HeapTupleIsValid(avTup)) avForm = (Form_pg_autovacuum) GETSTRUCT(avTup); /* Fetch the pgstat entry for this table */ tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared, shared, dbentry); relation_check_autovac(relid, classForm, avForm, tabentry, &table_oids, &table_toast_list, &toast_oids); if (HeapTupleIsValid(avTup)) heap_freetuple(avTup); } heap_endscan(relScan); heap_close(avRel, AccessShareLock); heap_close(classRel, AccessShareLock); /* * Add to the list of tables to vacuum, the OIDs of the tables that * correspond to the saved OIDs of toast tables needing vacuum. */ foreach (cell, toast_oids) { Oid toastoid = lfirst_oid(cell); ListCell *cell2; foreach (cell2, table_toast_list) { av_relation *ar = lfirst(cell2); if (ar->ar_toastrelid == toastoid) { table_oids = lappend_oid(table_oids, ar->ar_relid); break; } } } list_free_deep(table_toast_list); table_toast_list = NIL; list_free(toast_oids); toast_oids = NIL; /* * Perform operations on collected tables. */ foreach(cell, table_oids) { Oid relid = lfirst_oid(cell); autovac_table *tab; char *relname; CHECK_FOR_INTERRUPTS(); /* * Check whether pgstat data still says we need to vacuum this table. * It could have changed if something else processed the table while we * weren't looking. * * FIXME we ignore the possibility that the table was finished being * vacuumed in the last 500ms (PGSTAT_STAT_INTERVAL). This is a bug. */ tab = table_recheck_autovac(relid); if (tab == NULL) { /* someone else vacuumed the table */ continue; } /* Ok, good to go! */ /* Set the vacuum cost parameters for this table */ VacuumCostDelay = tab->at_vacuum_cost_delay; VacuumCostLimit = tab->at_vacuum_cost_limit; relname = get_rel_name(relid); elog(DEBUG2, "autovac: will%s%s %s", (tab->at_dovacuum ? " VACUUM" : ""), (tab->at_doanalyze ? " ANALYZE" : ""), relname); autovacuum_do_vac_analyze(tab->at_relid, tab->at_dovacuum, tab->at_doanalyze, tab->at_freeze_min_age); /* be tidy */ pfree(tab); pfree(relname); } /* * Update pg_database.datfrozenxid, and truncate pg_clog if possible. * We only need to do this once, not after each table. */ vac_update_datfrozenxid(); /* Finally close out the last transaction. */ CommitTransactionCommand(); } /* * Returns a copy of the pg_autovacuum tuple for the given relid, or NULL if * there isn't any. avRel is pg_autovacuum, already open and suitably locked. */ static HeapTuple get_pg_autovacuum_tuple_relid(Relation avRel, Oid relid) { ScanKeyData entry[1]; SysScanDesc avScan; HeapTuple avTup; ScanKeyInit(&entry[0], Anum_pg_autovacuum_vacrelid, BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(relid)); avScan = systable_beginscan(avRel, AutovacuumRelidIndexId, true, SnapshotNow, 1, entry); avTup = systable_getnext(avScan); if (HeapTupleIsValid(avTup)) avTup = heap_copytuple(avTup); systable_endscan(avScan); return avTup; } /* * get_pgstat_tabentry_relid * * Fetch the pgstat entry of a table, either local to a database or shared. */ static PgStat_StatTabEntry * get_pgstat_tabentry_relid(Oid relid, bool isshared, PgStat_StatDBEntry *shared, PgStat_StatDBEntry *dbentry) { PgStat_StatTabEntry *tabentry = NULL; if (isshared) { if (PointerIsValid(shared)) tabentry = hash_search(shared->tables, &relid, HASH_FIND, NULL); } else if (PointerIsValid(dbentry)) tabentry = hash_search(dbentry->tables, &relid, HASH_FIND, NULL); return tabentry; } /* * relation_check_autovac * * For a given relation (either a plain table or TOAST table), check whether it * needs vacuum or analyze. * * Plain tables that need either are added to the table_list. TOAST tables * that need vacuum are added to toast_list. Plain tables that don't need * either but which have a TOAST table are added, as a struct, to * table_toast_list. The latter is to allow appending the OIDs of the plain * tables whose TOAST table needs vacuuming into the plain tables list, which * allows us to substantially reduce the number of "rechecks" that we need to * do later on. */ static void relation_check_autovac(Oid relid, Form_pg_class classForm, Form_pg_autovacuum avForm, PgStat_StatTabEntry *tabentry, List **table_oids, List **table_toast_list, List **toast_oids) { bool dovacuum; bool doanalyze; relation_needs_vacanalyze(relid, avForm, classForm, tabentry, &dovacuum, &doanalyze); if (classForm->relkind == RELKIND_TOASTVALUE) { if (dovacuum) *toast_oids = lappend_oid(*toast_oids, relid); } else { Assert(classForm->relkind == RELKIND_RELATION); if (dovacuum || doanalyze) *table_oids = lappend_oid(*table_oids, relid); else if (OidIsValid(classForm->reltoastrelid)) { av_relation *rel = palloc(sizeof(av_relation)); rel->ar_relid = relid; rel->ar_toastrelid = classForm->reltoastrelid; *table_toast_list = lappend(*table_toast_list, rel); } } } /* * table_recheck_autovac * * Recheck whether a plain table still needs vacuum or analyze; be it because * it does directly, or because its TOAST table does. Return value is a valid * autovac_table pointer if it does, NULL otherwise. */ static autovac_table * table_recheck_autovac(Oid relid) { Form_pg_autovacuum avForm = NULL; Form_pg_class classForm; HeapTuple classTup; HeapTuple avTup; Relation avRel; bool dovacuum; bool doanalyze; autovac_table *tab = NULL; PgStat_StatTabEntry *tabentry; bool doit = false; PgStat_StatDBEntry *shared; PgStat_StatDBEntry *dbentry; /* We need fresh pgstat data for this */ pgstat_clear_snapshot(); shared = pgstat_fetch_stat_dbentry(InvalidOid); dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId); /* fetch the relation's relcache entry */ classTup = SearchSysCacheCopy(RELOID, ObjectIdGetDatum(relid), 0, 0, 0); if (!HeapTupleIsValid(classTup)) return NULL; classForm = (Form_pg_class) GETSTRUCT(classTup); /* fetch the pg_autovacuum entry, if any */ avRel = heap_open(AutovacuumRelationId, AccessShareLock); avTup = get_pg_autovacuum_tuple_relid(avRel, relid); if (HeapTupleIsValid(avTup)) avForm = (Form_pg_autovacuum) GETSTRUCT(avTup); /* fetch the pgstat table entry */ tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared, shared, dbentry); relation_needs_vacanalyze(relid, avForm, classForm, tabentry, &dovacuum, &doanalyze); /* OK, it needs vacuum by itself */ if (dovacuum) doit = true; /* it doesn't need vacuum, but what about it's TOAST table? */ else if (OidIsValid(classForm->reltoastrelid)) { Oid toastrelid = classForm->reltoastrelid; HeapTuple toastClassTup; toastClassTup = SearchSysCacheCopy(RELOID, ObjectIdGetDatum(toastrelid), 0, 0, 0); if (HeapTupleIsValid(toastClassTup)) { bool toast_dovacuum; bool toast_doanalyze; Form_pg_class toastClassForm; PgStat_StatTabEntry *toasttabentry; toastClassForm = (Form_pg_class) GETSTRUCT(toastClassTup); toasttabentry = get_pgstat_tabentry_relid(toastrelid, toastClassForm->relisshared, shared, dbentry); /* note we use the pg_autovacuum entry for the main table */ relation_needs_vacanalyze(toastrelid, avForm, toastClassForm, toasttabentry, &toast_dovacuum, &toast_doanalyze); /* we only consider VACUUM for toast tables */ if (toast_dovacuum) { dovacuum = true; doit = true; } heap_freetuple(toastClassTup); } } if (doanalyze) doit = true; if (doit) { int freeze_min_age; int vac_cost_limit; int vac_cost_delay; /* * Calculate the vacuum cost parameters and the minimum freeze age. If * there is a tuple in pg_autovacuum, use it; else, use the GUC * defaults. Note that the fields may contain "-1" (or indeed any * negative value), which means use the GUC defaults for each setting. */ if (avForm != NULL) { vac_cost_limit = (avForm->vac_cost_limit >= 0) ? avForm->vac_cost_limit : ((autovacuum_vac_cost_limit >= 0) ? autovacuum_vac_cost_limit : VacuumCostLimit); vac_cost_delay = (avForm->vac_cost_delay >= 0) ? avForm->vac_cost_delay : ((autovacuum_vac_cost_delay >= 0) ? autovacuum_vac_cost_delay : VacuumCostDelay); freeze_min_age = (avForm->freeze_min_age >= 0) ? avForm->freeze_min_age : default_freeze_min_age; } else { vac_cost_limit = (autovacuum_vac_cost_limit >= 0) ? autovacuum_vac_cost_limit : VacuumCostLimit; vac_cost_delay = (autovacuum_vac_cost_delay >= 0) ? autovacuum_vac_cost_delay : VacuumCostDelay; freeze_min_age = default_freeze_min_age; } tab = palloc(sizeof(autovac_table)); tab->at_relid = relid; tab->at_dovacuum = dovacuum; tab->at_doanalyze = doanalyze; tab->at_freeze_min_age = freeze_min_age; tab->at_vacuum_cost_limit = vac_cost_limit; tab->at_vacuum_cost_delay = vac_cost_delay; } heap_close(avRel, AccessShareLock); if (HeapTupleIsValid(avTup)) heap_freetuple(avTup); heap_freetuple(classTup); return tab; } /* * relation_needs_vacanalyze * * Check whether a relation needs to be vacuumed or analyzed; return each into * "dovacuum" and "doanalyze", respectively. avForm and tabentry can be NULL, * classForm shouldn't. * * A table needs to be vacuumed if the number of dead tuples exceeds a * threshold. This threshold is calculated as * * threshold = vac_base_thresh + vac_scale_factor * reltuples * * For analyze, the analysis done is that the number of tuples inserted, * deleted and updated since the last analyze exceeds a threshold calculated * in the same fashion as above. Note that the collector actually stores * the number of tuples (both live and dead) that there were as of the last * analyze. This is asymmetric to the VACUUM case. * * We also force vacuum if the table's relfrozenxid is more than freeze_max_age * transactions back. * * A table whose pg_autovacuum.enabled value is false, is automatically * skipped (unless we have to vacuum it due to freeze_max_age). Thus * autovacuum can be disabled for specific tables. Also, when the stats * collector does not have data about a table, it will be skipped. * * A table whose vac_base_thresh value is <0 takes the base value from the * autovacuum_vacuum_threshold GUC variable. Similarly, a vac_scale_factor * value <0 is substituted with the value of * autovacuum_vacuum_scale_factor GUC variable. Ditto for analyze. */ static void relation_needs_vacanalyze(Oid relid, Form_pg_autovacuum avForm, Form_pg_class classForm, PgStat_StatTabEntry *tabentry, /* output params below */ bool *dovacuum, bool *doanalyze) { bool force_vacuum; float4 reltuples; /* pg_class.reltuples */ /* constants from pg_autovacuum or GUC variables */ int vac_base_thresh, anl_base_thresh; float4 vac_scale_factor, anl_scale_factor; /* thresholds calculated from above constants */ float4 vacthresh, anlthresh; /* number of vacuum (resp. analyze) tuples at this time */ float4 vactuples, anltuples; /* freeze parameters */ int freeze_max_age; TransactionId xidForceLimit; AssertArg(classForm != NULL); AssertArg(OidIsValid(relid)); /* * Determine vacuum/analyze equation parameters. If there is a tuple in * pg_autovacuum, use it; else, use the GUC defaults. Note that the fields * may contain "-1" (or indeed any negative value), which means use the GUC * defaults for each setting. */ if (avForm != NULL) { vac_scale_factor = (avForm->vac_scale_factor >= 0) ? avForm->vac_scale_factor : autovacuum_vac_scale; vac_base_thresh = (avForm->vac_base_thresh >= 0) ? avForm->vac_base_thresh : autovacuum_vac_thresh; anl_scale_factor = (avForm->anl_scale_factor >= 0) ? avForm->anl_scale_factor : autovacuum_anl_scale; anl_base_thresh = (avForm->anl_base_thresh >= 0) ? avForm->anl_base_thresh : autovacuum_anl_thresh; freeze_max_age = (avForm->freeze_max_age >= 0) ? Min(avForm->freeze_max_age, autovacuum_freeze_max_age) : autovacuum_freeze_max_age; } else { vac_scale_factor = autovacuum_vac_scale; vac_base_thresh = autovacuum_vac_thresh; anl_scale_factor = autovacuum_anl_scale; anl_base_thresh = autovacuum_anl_thresh; freeze_max_age = autovacuum_freeze_max_age; } /* Force vacuum if table is at risk of wraparound */ xidForceLimit = recentXid - freeze_max_age; if (xidForceLimit < FirstNormalTransactionId) xidForceLimit -= FirstNormalTransactionId; force_vacuum = (TransactionIdIsNormal(classForm->relfrozenxid) && TransactionIdPrecedes(classForm->relfrozenxid, xidForceLimit)); /* User disabled it in pg_autovacuum? (But ignore if at risk) */ if (avForm && !avForm->enabled && !force_vacuum) { *doanalyze = false; *dovacuum = false; return; } if (PointerIsValid(tabentry)) { reltuples = classForm->reltuples; vactuples = tabentry->n_dead_tuples; anltuples = tabentry->n_live_tuples + tabentry->n_dead_tuples - tabentry->last_anl_tuples; vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples; anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples; /* * Note that we don't need to take special consideration for stat * reset, because if that happens, the last vacuum and analyze counts * will be reset too. */ elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)", NameStr(classForm->relname), vactuples, vacthresh, anltuples, anlthresh); /* Determine if this table needs vacuum or analyze. */ *dovacuum = force_vacuum || (vactuples > vacthresh); *doanalyze = (anltuples > anlthresh); } else { /* * Skip a table not found in stat hash, unless we have to force * vacuum for anti-wrap purposes. If it's not acted upon, there's * no need to vacuum it. */ *dovacuum = force_vacuum; *doanalyze = false; } /* ANALYZE refuses to work with pg_statistics */ if (relid == StatisticRelationId) *doanalyze = false; } /* * autovacuum_do_vac_analyze * Vacuum and/or analyze the specified table */ static void autovacuum_do_vac_analyze(Oid relid, bool dovacuum, bool doanalyze, int freeze_min_age) { VacuumStmt vacstmt; MemoryContext old_cxt; MemSet(&vacstmt, 0, sizeof(vacstmt)); /* * The list must survive transaction boundaries, so make sure we create it * in a long-lived context */ old_cxt = MemoryContextSwitchTo(AutovacMemCxt); /* Set up command parameters */ vacstmt.type = T_VacuumStmt; vacstmt.vacuum = dovacuum; vacstmt.full = false; vacstmt.analyze = doanalyze; vacstmt.freeze_min_age = freeze_min_age; vacstmt.verbose = false; vacstmt.relation = NULL; /* not used since we pass a relids list */ vacstmt.va_cols = NIL; /* Let pgstat know what we're doing */ autovac_report_activity(&vacstmt, relid); vacuum(&vacstmt, list_make1_oid(relid), true); MemoryContextSwitchTo(old_cxt); } /* * autovac_report_activity * Report to pgstat what autovacuum is doing * * We send a SQL string corresponding to what the user would see if the * equivalent command was to be issued manually. * * Note we assume that we are going to report the next command as soon as we're * done with the current one, and exiting right after the last one, so we don't * bother to report "" or some such. */ static void autovac_report_activity(VacuumStmt *vacstmt, Oid relid) { char *relname = get_rel_name(relid); char *nspname = get_namespace_name(get_rel_namespace(relid)); #define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 32) char activity[MAX_AUTOVAC_ACTIV_LEN]; /* Report the command and possible options */ if (vacstmt->vacuum) snprintf(activity, MAX_AUTOVAC_ACTIV_LEN, "VACUUM%s", vacstmt->analyze ? " ANALYZE" : ""); else snprintf(activity, MAX_AUTOVAC_ACTIV_LEN, "ANALYZE"); /* * Report the qualified name of the relation. * * Paranoia is appropriate here in case relation was recently dropped * --- the lsyscache routines we just invoked will return NULL rather * than failing. */ if (relname && nspname) { int len = strlen(activity); snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len, " %s.%s", nspname, relname); } pgstat_report_activity(activity); } /* * AutoVacuumingActive * Check GUC vars and report whether the autovacuum process should be * running. */ bool AutoVacuumingActive(void) { if (!autovacuum_start_daemon || !pgstat_collect_startcollector || !pgstat_collect_tuplelevel) return false; return true; } /* * autovac_init * This is called at postmaster initialization. * * Annoy the user if he got it wrong. */ void autovac_init(void) { if (!autovacuum_start_daemon) return; if (!pgstat_collect_startcollector || !pgstat_collect_tuplelevel) { ereport(WARNING, (errmsg("autovacuum not started because of misconfiguration"), errhint("Enable options \"stats_start_collector\" and \"stats_row_level\"."))); /* * Set the GUC var so we don't fork autovacuum uselessly, and also to * help debugging. */ autovacuum_start_daemon = false; } } /* * IsAutoVacuum functions * Return whether this is either a launcher autovacuum process or a worker * process. */ bool IsAutoVacuumLauncherProcess(void) { return am_autovacuum_launcher; } bool IsAutoVacuumWorkerProcess(void) { return am_autovacuum_worker; } /* * AutoVacuumShmemSize * Compute space needed for autovacuum-related shared memory */ Size AutoVacuumShmemSize(void) { return sizeof(AutoVacuumShmemStruct); } /* * AutoVacuumShmemInit * Allocate and initialize autovacuum-related shared memory */ void AutoVacuumShmemInit(void) { bool found; AutoVacuumShmem = (AutoVacuumShmemStruct *) ShmemInitStruct("AutoVacuum Data", AutoVacuumShmemSize(), &found); if (AutoVacuumShmem == NULL) ereport(FATAL, (errcode(ERRCODE_OUT_OF_MEMORY), errmsg("not enough shared memory for autovacuum"))); if (found) return; /* already initialized */ MemSet(AutoVacuumShmem, 0, sizeof(AutoVacuumShmemStruct)); }