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53bb309d2d
The logic introduced in commitb69bf30b9band repaired in commits669c7d20e6and7be47c56afhelps to ensure that we don't overwrite old multixact member information while it is still needed, but a user who creates many large multixacts can still exhaust the member space (and thus start getting errors) while autovacuum stands idly by. To fix this, progressively ramp down the effective value (but not the actual contents) of autovacuum_multixact_freeze_max_age as member space utilization increases. This makes autovacuum more aggressive and also reduces the threshold for a manual VACUUM to perform a full-table scan. This patch leaves unsolved the problem of ensuring that emergency autovacuums are triggered even when autovacuum=off. We'll need to fix that via a separate patch. Thomas Munro and Robert Haas
145 lines
4.7 KiB
C
145 lines
4.7 KiB
C
/*
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* multixact.h
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*
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* PostgreSQL multi-transaction-log manager
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*
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* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/multixact.h
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*/
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#ifndef MULTIXACT_H
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#define MULTIXACT_H
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#include "access/xlogreader.h"
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#include "lib/stringinfo.h"
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/*
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* The first two MultiXactId values are reserved to store the truncation Xid
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* and epoch of the first segment, so we start assigning multixact values from
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* 2.
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*/
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#define InvalidMultiXactId ((MultiXactId) 0)
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#define FirstMultiXactId ((MultiXactId) 1)
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#define MaxMultiXactId ((MultiXactId) 0xFFFFFFFF)
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#define MultiXactIdIsValid(multi) ((multi) != InvalidMultiXactId)
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#define MaxMultiXactOffset ((MultiXactOffset) 0xFFFFFFFF)
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/* Number of SLRU buffers to use for multixact */
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#define NUM_MXACTOFFSET_BUFFERS 8
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#define NUM_MXACTMEMBER_BUFFERS 16
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/*
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* Possible multixact lock modes ("status"). The first four modes are for
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* tuple locks (FOR KEY SHARE, FOR SHARE, FOR NO KEY UPDATE, FOR UPDATE); the
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* next two are used for update and delete modes.
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*/
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typedef enum
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{
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MultiXactStatusForKeyShare = 0x00,
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MultiXactStatusForShare = 0x01,
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MultiXactStatusForNoKeyUpdate = 0x02,
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MultiXactStatusForUpdate = 0x03,
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/* an update that doesn't touch "key" columns */
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MultiXactStatusNoKeyUpdate = 0x04,
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/* other updates, and delete */
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MultiXactStatusUpdate = 0x05
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} MultiXactStatus;
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#define MaxMultiXactStatus MultiXactStatusUpdate
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/* does a status value correspond to a tuple update? */
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#define ISUPDATE_from_mxstatus(status) \
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((status) > MultiXactStatusForUpdate)
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typedef struct MultiXactMember
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{
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TransactionId xid;
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MultiXactStatus status;
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} MultiXactMember;
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/* ----------------
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* multixact-related XLOG entries
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* ----------------
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*/
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#define XLOG_MULTIXACT_ZERO_OFF_PAGE 0x00
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#define XLOG_MULTIXACT_ZERO_MEM_PAGE 0x10
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#define XLOG_MULTIXACT_CREATE_ID 0x20
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typedef struct xl_multixact_create
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{
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MultiXactId mid; /* new MultiXact's ID */
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MultiXactOffset moff; /* its starting offset in members file */
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int32 nmembers; /* number of member XIDs */
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MultiXactMember members[FLEXIBLE_ARRAY_MEMBER];
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} xl_multixact_create;
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#define SizeOfMultiXactCreate (offsetof(xl_multixact_create, members))
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extern MultiXactId MultiXactIdCreate(TransactionId xid1,
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MultiXactStatus status1, TransactionId xid2,
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MultiXactStatus status2);
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extern MultiXactId MultiXactIdExpand(MultiXactId multi, TransactionId xid,
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MultiXactStatus status);
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extern MultiXactId MultiXactIdCreateFromMembers(int nmembers,
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MultiXactMember *members);
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extern MultiXactId ReadNextMultiXactId(void);
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extern bool MultiXactIdIsRunning(MultiXactId multi, bool isLockOnly);
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extern void MultiXactIdSetOldestMember(void);
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extern int GetMultiXactIdMembers(MultiXactId multi, MultiXactMember **xids,
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bool allow_old, bool isLockOnly);
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extern bool MultiXactIdPrecedes(MultiXactId multi1, MultiXactId multi2);
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extern bool MultiXactIdPrecedesOrEquals(MultiXactId multi1,
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MultiXactId multi2);
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extern void AtEOXact_MultiXact(void);
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extern void AtPrepare_MultiXact(void);
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extern void PostPrepare_MultiXact(TransactionId xid);
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extern Size MultiXactShmemSize(void);
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extern void MultiXactShmemInit(void);
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extern void BootStrapMultiXact(void);
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extern void StartupMultiXact(void);
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extern void TrimMultiXact(void);
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extern void ShutdownMultiXact(void);
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extern void SetMultiXactIdLimit(MultiXactId oldest_datminmxid,
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Oid oldest_datoid);
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extern void MultiXactGetCheckptMulti(bool is_shutdown,
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MultiXactId *nextMulti,
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MultiXactOffset *nextMultiOffset,
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MultiXactId *oldestMulti,
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Oid *oldestMultiDB);
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extern void CheckPointMultiXact(void);
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extern MultiXactId GetOldestMultiXactId(void);
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extern void TruncateMultiXact(void);
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extern void MultiXactSetNextMXact(MultiXactId nextMulti,
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MultiXactOffset nextMultiOffset);
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extern void MultiXactAdvanceNextMXact(MultiXactId minMulti,
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MultiXactOffset minMultiOffset);
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extern void MultiXactAdvanceOldest(MultiXactId oldestMulti, Oid oldestMultiDB);
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extern void MultiXactSetSafeTruncate(MultiXactId safeTruncateMulti);
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extern int MultiXactMemberFreezeThreshold(void);
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extern void multixact_twophase_recover(TransactionId xid, uint16 info,
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void *recdata, uint32 len);
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extern void multixact_twophase_postcommit(TransactionId xid, uint16 info,
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void *recdata, uint32 len);
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extern void multixact_twophase_postabort(TransactionId xid, uint16 info,
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void *recdata, uint32 len);
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extern void multixact_redo(XLogReaderState *record);
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extern void multixact_desc(StringInfo buf, XLogReaderState *record);
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extern const char *multixact_identify(uint8 info);
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extern char *mxid_to_string(MultiXactId multi, int nmembers,
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MultiXactMember *members);
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#endif /* MULTIXACT_H */
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