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Rearrange pg_subtrans handling as per recent discussion. pg_subtrans
updates are no longer WAL-logged nor even fsync'd; we do not need to, since after a crash no old pg_subtrans data is needed again. We truncate pg_subtrans to RecentGlobalXmin at each checkpoint. slru.c's API is refactored a little bit to separate out the necessary decisions.
This commit is contained in:
Tom Lane
@@ -6,7 +6,7 @@
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* Portions Copyright (c) 1996-2003, 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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* $PostgreSQL: pgsql/src/include/access/clog.h,v 1.9 2004/07/01 00:51:38 tgl Exp $
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* $PostgreSQL: pgsql/src/include/access/clog.h,v 1.10 2004/08/23 23:22:45 tgl Exp $
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*/
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#ifndef CLOG_H
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#define CLOG_H
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@@ -27,9 +27,6 @@ typedef int XidStatus;
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#define TRANSACTION_STATUS_ABORTED 0x02
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#define TRANSACTION_STATUS_SUB_COMMITTED 0x03
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/* exported because lwlock.c needs it */
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#define NUM_CLOG_BUFFERS 8
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extern void TransactionIdSetStatus(TransactionId xid, XidStatus status);
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extern XidStatus TransactionIdGetStatus(TransactionId xid);
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@@ -42,6 +39,12 @@ extern void ShutdownCLOG(void);
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extern void CheckPointCLOG(void);
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extern void ExtendCLOG(TransactionId newestXact);
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extern void TruncateCLOG(TransactionId oldestXact);
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extern void clog_zeropage_redo(int pageno);
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/* XLOG stuff */
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#define CLOG_ZEROPAGE 0x00
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extern void clog_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void clog_undo(XLogRecPtr lsn, XLogRecord *record);
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extern void clog_desc(char *buf, uint8 xl_info, char *rec);
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#endif /* CLOG_H */
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@@ -3,7 +3,7 @@
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*
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* Resource managers definition
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*
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* $PostgreSQL: pgsql/src/include/access/rmgr.h,v 1.11 2004/07/01 00:51:38 tgl Exp $
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* $PostgreSQL: pgsql/src/include/access/rmgr.h,v 1.12 2004/08/23 23:22:45 tgl Exp $
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*/
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#ifndef RMGR_H
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#define RMGR_H
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@@ -16,7 +16,7 @@ typedef uint8 RmgrId;
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#define RM_XLOG_ID 0
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#define RM_XACT_ID 1
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#define RM_SMGR_ID 2
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#define RM_SLRU_ID 3
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#define RM_CLOG_ID 3
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#define RM_HEAP_ID 10
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#define RM_BTREE_ID 11
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#define RM_HASH_ID 12
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@@ -1,23 +1,66 @@
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/*
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/*-------------------------------------------------------------------------
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*
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* slru.h
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* Simple LRU buffering for transaction status logfiles
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*
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* Simple LRU
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*
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* Portions Copyright (c) 2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1996-2003, 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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* $PostgreSQL: pgsql/src/include/access/slru.h,v 1.7 2004/07/01 00:51:38 tgl Exp $
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* $PostgreSQL: pgsql/src/include/access/slru.h,v 1.8 2004/08/23 23:22:45 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SLRU_H
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#define SLRU_H
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#include "access/xlog.h"
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#include "storage/lwlock.h"
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/* Opaque structs known only in slru.c */
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typedef struct SlruSharedData *SlruShared;
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typedef struct SlruFlushData *SlruFlush;
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/*
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* Number of page buffers. Ideally this could be different for CLOG and
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* SUBTRANS, but the benefit doesn't seem to be worth any additional
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* notational cruft.
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*/
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#define NUM_SLRU_BUFFERS 8
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/* Page status codes */
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typedef enum
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{
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SLRU_PAGE_EMPTY, /* buffer is not in use */
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SLRU_PAGE_READ_IN_PROGRESS, /* page is being read in */
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SLRU_PAGE_CLEAN, /* page is valid and not dirty */
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SLRU_PAGE_DIRTY, /* page is valid but needs write */
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SLRU_PAGE_WRITE_IN_PROGRESS /* page is being written out */
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} SlruPageStatus;
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/*
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* Shared-memory state
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*/
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typedef struct SlruSharedData
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{
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LWLockId ControlLock;
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/*
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* Info for each buffer slot. Page number is undefined when status is
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* EMPTY. lru_count is essentially the number of page switches since
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* last use of this page; the page with highest lru_count is the best
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* candidate to replace.
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*/
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char *page_buffer[NUM_SLRU_BUFFERS];
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SlruPageStatus page_status[NUM_SLRU_BUFFERS];
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int page_number[NUM_SLRU_BUFFERS];
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unsigned int page_lru_count[NUM_SLRU_BUFFERS];
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LWLockId buffer_locks[NUM_SLRU_BUFFERS];
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/*
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* latest_page_number is the page number of the current end of the
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* log; this is not critical data, since we use it only to avoid
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* swapping out the latest page.
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*/
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int latest_page_number;
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} SlruSharedData;
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typedef SlruSharedData *SlruShared;
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/*
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* SlruCtlData is an unshared structure that points to the active information
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@@ -27,13 +70,11 @@ typedef struct SlruCtlData
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{
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SlruShared shared;
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LWLockId ControlLock;
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/*
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* Dir is set during SimpleLruInit and does not change thereafter.
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* Since it's always the same, it doesn't need to be in shared memory.
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* This flag tells whether to fsync writes (true for pg_clog,
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* false for pg_subtrans).
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*/
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char Dir[MAXPGPATH];
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bool do_fsync;
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/*
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* Decide which of two page numbers is "older" for truncation purposes.
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@@ -42,27 +83,27 @@ typedef struct SlruCtlData
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*/
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bool (*PagePrecedes) (int, int);
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/*
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* Dir is set during SimpleLruInit and does not change thereafter.
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* Since it's always the same, it doesn't need to be in shared memory.
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*/
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char Dir[MAXPGPATH];
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} SlruCtlData;
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typedef SlruCtlData *SlruCtl;
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/* Opaque struct known only in slru.c */
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typedef struct SlruFlushData *SlruFlush;
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extern int SimpleLruShmemSize(void);
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extern void SimpleLruInit(SlruCtl ctl, const char *name, const char *subdir);
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extern void SimpleLruInit(SlruCtl ctl, const char *name,
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LWLockId ctllock, const char *subdir);
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extern int SimpleLruZeroPage(SlruCtl ctl, int pageno);
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extern char *SimpleLruReadPage(SlruCtl ctl, int pageno,
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TransactionId xid, bool forwrite);
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extern int SimpleLruReadPage(SlruCtl ctl, int pageno, TransactionId xid);
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extern void SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata);
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extern void SimpleLruSetLatestPage(SlruCtl ctl, int pageno);
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extern void SimpleLruFlush(SlruCtl ctl, bool checkpoint);
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extern void SimpleLruTruncate(SlruCtl ctl, int cutoffPage);
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/* XLOG stuff */
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#define CLOG_ZEROPAGE 0x00
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#define SUBTRANS_ZEROPAGE 0x10
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extern void slru_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void slru_undo(XLogRecPtr lsn, XLogRecord *record);
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extern void slru_desc(char *buf, uint8 xl_info, char *rec);
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extern bool SlruScanDirectory(SlruCtl ctl, int cutoffPage, bool doDeletions);
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#endif /* SLRU_H */
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@@ -1,22 +1,16 @@
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/*
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* subtrans.h
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*
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* PostgreSQL subtrans-log manager
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* PostgreSQL subtransaction-log manager
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*
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* Portions Copyright (c) 1996-2003, 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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* $PostgreSQL: pgsql/src/include/access/subtrans.h,v 1.2 2004/08/22 02:41:58 tgl Exp $
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* $PostgreSQL: pgsql/src/include/access/subtrans.h,v 1.3 2004/08/23 23:22:45 tgl Exp $
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*/
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#ifndef SUBTRANS_H
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#define SUBTRANS_H
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#include "access/xlog.h"
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/* exported because lwlock.c needs it */
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/* cannot be different from NUM_CLOG_BUFFERS without slru.c changes */
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#define NUM_SUBTRANS_BUFFERS NUM_CLOG_BUFFERS
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extern void SubTransSetParent(TransactionId xid, TransactionId parent);
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extern TransactionId SubTransGetParent(TransactionId xid);
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extern TransactionId SubTransGetTopmostTransaction(TransactionId xid);
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@@ -29,6 +23,5 @@ extern void ShutdownSUBTRANS(void);
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extern void CheckPointSUBTRANS(void);
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extern void ExtendSUBTRANS(TransactionId newestXact);
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extern void TruncateSUBTRANS(TransactionId oldestXact);
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extern void subtrans_zeropage_redo(int pageno);
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#endif /* SUBTRANS_H */
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