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/*-------------------------------------------------------------------------
*
* transam.h
* postgres transaction access method support code header
*
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: transam.h,v 1.19 1999/02/13 23:20:59 momjian Exp $
*
* NOTES
* Transaction System Version 101 now support proper oid
* generation and recording in the variable relation.
*
*-------------------------------------------------------------------------
*/
#ifndef TRANSAM_H
#define TRANSAM_H
#include <storage/bufmgr.h>
/* ----------------
* transaction system version id
*
* this is stored on the first page of the log, time and variable
* relations on the first 4 bytes. This is so that if we improve
* the format of the transaction log after postgres version 2, then
* people won't have to rebuild their databases.
*
* TRANS_SYSTEM_VERSION 100 means major version 1 minor version 0.
* Two databases with the same major version should be compatible,
* even if their minor versions differ.
* ----------------
*/
#define TRANS_SYSTEM_VERSION 200
/* ----------------
* transaction id status values
*
* someday we will use "11" = 3 = XID_COMMIT_CHILD to mean the
* commiting of child xactions.
* ----------------
*/
#define XID_COMMIT 2 /* transaction commited */
#define XID_ABORT 1 /* transaction aborted */
#define XID_INPROGRESS 0 /* transaction in progress */
#define XID_COMMIT_CHILD 3 /* child xact commited */
typedef unsigned char XidStatus;/* (2 bits) */
/* ----------
* note: we reserve the first 16384 object ids for internal use.
* oid's less than this appear in the .bki files. the choice of
* 16384 is completely arbitrary.
* ----------
*/
#define BootstrapObjectIdData 16384
/* ----------------
* BitIndexOf computes the index of the Nth xid on a given block
* ----------------
*/
#define BitIndexOf(N) ((N) * 2)
/* ----------------
* transaction page definitions
* ----------------
*/
#define TP_DataSize BLCKSZ
#define TP_NumXidStatusPerBlock (TP_DataSize * 4)
/* ----------------
* LogRelationContents structure
*
* This structure describes the storage of the data in the
* first 128 bytes of the log relation. This storage is never
* used for transaction status because transaction id's begin
* their numbering at 512.
*
* The first 4 bytes of this relation store the version
* number of the transction system.
* ----------------
*/
typedef struct LogRelationContentsData
{
int TransSystemVersion;
} LogRelationContentsData;
typedef LogRelationContentsData *LogRelationContents;
/* ----------------
* VariableRelationContents structure
*
* The variable relation is a special "relation" which
* is used to store various system "variables" persistantly.
* Unlike other relations in the system, this relation
* is updated in place whenever the variables change.
*
* The first 4 bytes of this relation store the version
* number of the transction system.
*
* Currently, the relation has only one page and the next
* available xid, the last committed xid and the next
* available oid are stored there.
* ----------------
*/
typedef struct VariableRelationContentsData
{
int TransSystemVersion;
TransactionId nextXidData;
TransactionId lastXidData; /* unused */
Oid nextOid;
} VariableRelationContentsData;
typedef VariableRelationContentsData *VariableRelationContents;
/*
* VariableCache is placed in shmem and used by backends to
* get next available XID & OID without access to
* variable relation. Actually, I would like to have two
* different on-disk storages for next XID and OID...
* But hoping that someday we will use per database OID
* generator I leaved this as is. - vadim 07/21/98
*/
typedef struct VariableCacheData
{
uint32 xid_count;
TransactionId nextXid;
uint32 oid_count; /* not implemented, yet */
Oid nextOid;
} VariableCacheData;
typedef VariableCacheData *VariableCache;
/* ----------------
* extern declarations
* ----------------
*/
/*
* prototypes for functions in transam/transam.c
*/
extern void InitializeTransactionLog(void);
extern bool TransactionIdDidCommit(TransactionId transactionId);
extern bool TransactionIdDidAbort(TransactionId transactionId);
extern void TransactionIdCommit(TransactionId transactionId);
extern void TransactionIdAbort(TransactionId transactionId);
extern void TransactionIdFlushCache(void);
/* in transam/transsup.c */
extern void AmiTransactionOverride(bool flag);
extern void TransComputeBlockNumber(Relation relation,
TransactionId transactionId, BlockNumber *blockNumberOutP);
extern XidStatus TransBlockNumberGetXidStatus(Relation relation,
BlockNumber blockNumber, TransactionId xid, bool *failP);
extern void TransBlockNumberSetXidStatus(Relation relation,
BlockNumber blockNumber, TransactionId xid, XidStatus xstatus,
bool *failP);
/* in transam/varsup.c */
extern void VariableRelationPutNextXid(TransactionId xid);
extern void GetNewTransactionId(TransactionId *xid);
extern void ReadNewTransactionId(TransactionId *xid);
extern void GetNewObjectId(Oid *oid_return);
extern void CheckMaxObjectId(Oid assigned_oid);
/* ----------------
* global variable extern declarations
* ----------------
*/
/* in transam.c */
extern Relation LogRelation;
extern Relation VariableRelation;
extern TransactionId cachedTestXid;
extern XidStatus cachedTestXidStatus;
extern TransactionId NullTransactionId;
extern TransactionId AmiTransactionId;
extern TransactionId FirstTransactionId;
extern int RecoveryCheckingEnableState;
/* in transsup.c */
extern bool AMI_OVERRIDE;
/* in varsup.c */
extern int OidGenLockId;
#endif /* TRAMSAM_H */
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