Remove pg_vlock locking from VACUUM, allowing multiple VACUUMs to run in
parallel --- and, not incidentally, removing a common reason for needing manual cleanup by the DB admin after a crash. Remove initial global delete of pg_statistics rows in VACUUM ANALYZE; this was not only bad for performance of other backends that had to run without stats for a while, but it was fundamentally broken because it was done outside any transaction. Surprising we didn't see more consequences of that. Detect attempt to run VACUUM inside a transaction block. Check for query cancel request before starting vacuum of each table. Clean up vacuum's private portal storage if vacuum is aborted.
This commit is contained in:
Tom Lane
parent
d2914c38b6
commit
aa903cf07c
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.126 1999/11/25 00:15:57 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.127 1999/11/28 02:10:01 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -21,6 +21,7 @@
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#include "access/genam.h"
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#include "access/heapam.h"
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#include "access/xact.h"
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#include "catalog/catalog.h"
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#include "catalog/catname.h"
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#include "catalog/index.h"
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@ -33,6 +34,7 @@
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#include "parser/parse_oper.h"
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#include "storage/sinval.h"
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#include "storage/smgr.h"
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#include "tcop/tcopprot.h"
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#include "utils/builtins.h"
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#include "utils/inval.h"
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#include "utils/portal.h"
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@ -46,7 +48,6 @@
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#include <sys/resource.h>
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#endif
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/* #include <port-protos.h> *//* Why? */
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bool VacuumRunning = false;
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@ -80,11 +81,10 @@ static void vc_scanoneind(Relation indrel, int num_tuples);
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static void vc_attrstats(Relation onerel, VRelStats *vacrelstats, HeapTuple tuple);
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static void vc_bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len);
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static void vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *vacrelstats);
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static void vc_delhilowstats(Oid relid, int attcnt, int *attnums);
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static void vc_delstats(Oid relid, int attcnt, int *attnums);
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static VPageDescr vc_tidreapped(ItemPointer itemptr, VPageList vpl);
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static void vc_reappage(VPageList vpl, VPageDescr vpc);
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static void vc_vpinsert(VPageList vpl, VPageDescr vpnew);
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static void vc_free(VRelList vrl);
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static void vc_getindices(Oid relid, int *nindices, Relation **Irel);
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static void vc_clsindices(int nindices, Relation *Irel);
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static void vc_mkindesc(Relation onerel, int nindices, Relation *Irel, IndDesc **Idesc);
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@ -98,61 +98,55 @@ static bool vc_enough_space(VPageDescr vpd, Size len);
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void
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vacuum(char *vacrel, bool verbose, bool analyze, List *va_spec)
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{
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char *pname;
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MemoryContext old;
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PortalVariableMemory pmem;
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NameData VacRel;
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PortalVariableMemory pmem;
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MemoryContext old;
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List *le;
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List *va_cols = NIL;
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if (va_spec != NIL && !analyze)
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elog(ERROR, "Can't vacuum columns, only tables. You can 'vacuum analyze' columns.");
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/*
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* Create a portal for safe memory across transctions. We need to
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* palloc the name space for it because our hash function expects the
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* name to be on a longword boundary. CreatePortal copies the name to
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* safe storage for us.
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* We cannot run VACUUM inside a user transaction block; if we were
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* inside a transaction, then our commit- and start-transaction-command
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* calls would not have the intended effect! Furthermore, the forced
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* commit that occurs before truncating the relation's file would have
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* the effect of committing the rest of the user's transaction too,
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* which would certainly not be the desired behavior.
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*/
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pname = (char *) palloc(strlen(VACPNAME) + 1);
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strcpy(pname, VACPNAME);
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vc_portal = CreatePortal(pname);
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pfree(pname);
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if (IsTransactionBlock())
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elog(ERROR, "VACUUM cannot run inside a BEGIN/END block");
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/* initialize vacuum cleaner, particularly vc_portal */
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vc_init();
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if (verbose)
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MESSAGE_LEVEL = NOTICE;
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else
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MESSAGE_LEVEL = DEBUG;
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/* vacrel gets de-allocated on transaction commit */
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/* vacrel gets de-allocated on transaction commit, so copy it */
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if (vacrel)
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strcpy(NameStr(VacRel), vacrel);
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/* must also copy the column list, if any, to safe storage */
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pmem = PortalGetVariableMemory(vc_portal);
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old = MemoryContextSwitchTo((MemoryContext) pmem);
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if (va_spec != NIL && !analyze)
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elog(ERROR, "Can't vacuum columns, only tables. You can 'vacuum analyze' columns.");
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foreach(le, va_spec)
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{
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char *col = (char *) lfirst(le);
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char *dest;
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dest = (char *) palloc(strlen(col) + 1);
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strcpy(dest, col);
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va_cols = lappend(va_cols, dest);
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va_cols = lappend(va_cols, pstrdup(col));
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}
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MemoryContextSwitchTo(old);
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/* initialize vacuum cleaner */
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vc_init();
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/* vacuum the database */
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if (vacrel)
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vc_vacuum(&VacRel, analyze, va_cols);
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else
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vc_vacuum(NULL, analyze, NIL);
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PortalDestroy(&vc_portal);
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/* clean up */
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vc_shutdown();
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}
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@ -160,14 +154,17 @@ vacuum(char *vacrel, bool verbose, bool analyze, List *va_spec)
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/*
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* vc_init(), vc_shutdown() -- start up and shut down the vacuum cleaner.
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*
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* We run exactly one vacuum cleaner at a time. We use the file system
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* to guarantee an exclusive lock on vacuuming, since a single vacuum
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* cleaner instantiation crosses transaction boundaries, and we'd lose
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* postgres-style locks at the end of every transaction.
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* Formerly, there was code here to prevent more than one VACUUM from
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* executing concurrently in the same database. However, there's no
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* good reason to prevent that, and manually removing lockfiles after
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* a vacuum crash was a pain for dbadmins. So, forget about lockfiles,
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* and just rely on the exclusive lock we grab on each target table
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* to ensure that there aren't two VACUUMs running on the same table
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* at the same time.
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*
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* The strangeness with committing and starting transactions in the
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* init and shutdown routines is due to the fact that the vacuum cleaner
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* is invoked via a sql command, and so is already executing inside
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* is invoked via an SQL command, and so is already executing inside
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* a transaction. We need to leave ourselves in a predictable state
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* on entry and exit to the vacuum cleaner. We commit the transaction
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* started in PostgresMain() inside vc_init(), and start one in
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@ -177,27 +174,23 @@ vacuum(char *vacrel, bool verbose, bool analyze, List *va_spec)
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static void
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vc_init()
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{
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int fd;
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#ifndef __CYGWIN32__
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if ((fd = open("pg_vlock", O_CREAT | O_EXCL, 0600)) < 0)
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#else
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if ((fd = open("pg_vlock", O_CREAT | O_EXCL | O_BINARY, 0600)) < 0)
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#endif
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{
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elog(ERROR, "Can't create lock file. Is another vacuum cleaner running?\n\
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\tIf not, you may remove the pg_vlock file in the %s\n\
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\tdirectory", DatabasePath);
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}
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close(fd);
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char *pname;
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/*
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* By here, exclusive open on the lock file succeeded. If we abort
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* for any reason during vacuuming, we need to remove the lock file.
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* Create a portal for safe memory across transactions. We need to
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* palloc the name space for it because our hash function expects the
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* name to be on a longword boundary. CreatePortal copies the name to
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* safe storage for us.
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*/
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pname = pstrdup(VACPNAME);
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vc_portal = CreatePortal(pname);
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pfree(pname);
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/*
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* Set flag to indicate that vc_portal must be removed after an error.
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* This global variable is checked in the transaction manager on xact
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* abort, and the routine vc_abort() is called if necessary.
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*/
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VacuumRunning = true;
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/* matches the StartTransaction in PostgresMain() */
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@ -221,25 +214,28 @@ vc_shutdown()
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*/
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unlink(RELCACHE_INIT_FILENAME);
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/* remove the vacuum cleaner lock file */
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if (unlink("pg_vlock") < 0)
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elog(ERROR, "vacuum: can't destroy lock file!");
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/*
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* Release our portal for cross-transaction memory.
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*/
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PortalDestroy(&vc_portal);
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/* okay, we're done */
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VacuumRunning = false;
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/* matches the CommitTransaction in PostgresMain() */
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StartTransactionCommand();
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}
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void
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vc_abort()
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{
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/* on abort, remove the vacuum cleaner lock file */
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unlink("pg_vlock");
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/* Clear flag first, to avoid recursion if PortalDestroy elog's */
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VacuumRunning = false;
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/*
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* Release our portal for cross-transaction memory.
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*/
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PortalDestroy(&vc_portal);
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}
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/*
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@ -259,14 +255,9 @@ vc_vacuum(NameData *VacRelP, bool analyze, List *va_cols)
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/* get list of relations */
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vrl = vc_getrels(VacRelP);
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if (analyze && VacRelP == NULL && vrl != NULL)
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vc_delhilowstats(InvalidOid, 0, NULL);
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/* vacuum each heap relation */
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for (cur = vrl; cur != (VRelList) NULL; cur = cur->vrl_next)
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vc_vacone(cur->vrl_relid, analyze, va_cols);
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vc_free(vrl);
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}
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static VRelList
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@ -381,6 +372,13 @@ vc_vacone(Oid relid, bool analyze, List *va_cols)
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StartTransactionCommand();
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/*
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* Check for user-requested abort. Note we want this to be inside
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* a transaction, so xact.c doesn't issue useless NOTICE.
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*/
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if (QueryCancel)
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CancelQuery();
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/*
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* Race condition -- if the pg_class tuple has gone away since the
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* last time we saw it, we don't need to vacuum it.
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@ -500,7 +498,8 @@ vc_vacone(Oid relid, bool analyze, List *va_cols)
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stats->outfunc = InvalidOid;
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}
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vacrelstats->va_natts = attr_cnt;
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vc_delhilowstats(relid, ((attnums) ? attr_cnt : 0), attnums);
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/* delete existing pg_statistics rows for relation */
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vc_delstats(relid, ((attnums) ? attr_cnt : 0), attnums);
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if (attnums)
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pfree(attnums);
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}
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@ -2453,7 +2452,7 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
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CatalogIndexInsert(irelations, Num_pg_statistic_indices, sd, stup);
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CatalogCloseIndices(Num_pg_statistic_indices, irelations);
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}
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/* release allocated space */
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pfree(DatumGetPointer(values[Anum_pg_statistic_stacommonval-1]));
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pfree(DatumGetPointer(values[Anum_pg_statistic_staloval-1]));
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@ -2478,11 +2477,12 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
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}
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/*
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* vc_delhilowstats() -- delete pg_statistics rows
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* vc_delstats() -- delete pg_statistics rows for a relation
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*
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* If a list of attribute numbers is given, only zap stats for those attrs.
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*/
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static void
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vc_delhilowstats(Oid relid, int attcnt, int *attnums)
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vc_delstats(Oid relid, int attcnt, int *attnums)
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{
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Relation pgstatistic;
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HeapScanDesc scan;
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@ -2491,15 +2491,9 @@ vc_delhilowstats(Oid relid, int attcnt, int *attnums)
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pgstatistic = heap_openr(StatisticRelationName, RowExclusiveLock);
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if (relid != InvalidOid)
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{
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ScanKeyEntryInitialize(&key, 0x0, Anum_pg_statistic_starelid,
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F_OIDEQ,
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ObjectIdGetDatum(relid));
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scan = heap_beginscan(pgstatistic, false, SnapshotNow, 1, &key);
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}
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else
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scan = heap_beginscan(pgstatistic, false, SnapshotNow, 0, NULL);
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ScanKeyEntryInitialize(&key, 0x0, Anum_pg_statistic_starelid,
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F_OIDEQ, ObjectIdGetDatum(relid));
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scan = heap_beginscan(pgstatistic, false, SnapshotNow, 1, &key);
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while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
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{
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@ -2572,28 +2566,6 @@ vc_vpinsert(VPageList vpl, VPageDescr vpnew)
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}
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static void
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vc_free(VRelList vrl)
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{
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VRelList p_vrl;
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MemoryContext old;
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PortalVariableMemory pmem;
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pmem = PortalGetVariableMemory(vc_portal);
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old = MemoryContextSwitchTo((MemoryContext) pmem);
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while (vrl != (VRelList) NULL)
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{
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/* free rel list entry */
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p_vrl = vrl;
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vrl = vrl->vrl_next;
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pfree(p_vrl);
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}
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MemoryContextSwitchTo(old);
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}
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static void *
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vc_find_eq(void *bot, int nelem, int size, void *elm,
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int (*compar) (const void *, const void *))
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