1996-08-28 03:59:28 +02:00
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/*-------------------------------------------------------------------------
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*
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* itemptr.h--
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1997-09-07 07:04:48 +02:00
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* POSTGRES disk item pointer definitions.
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1996-08-28 03:59:28 +02:00
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*
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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1997-09-08 23:56:23 +02:00
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* $Id: itemptr.h,v 1.7 1997/09/08 21:54:25 momjian Exp $
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1996-08-28 03:59:28 +02:00
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*
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*-------------------------------------------------------------------------
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*/
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1997-09-07 07:04:48 +02:00
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#ifndef ITEMPTR_H
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1996-08-28 03:59:28 +02:00
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#define ITEMPTR_H
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1996-11-04 08:18:46 +01:00
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#include <storage/off.h>
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#include <storage/block.h>
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1996-08-28 03:59:28 +02:00
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/*
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* ItemPointer:
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*
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* this is a pointer to an item on another disk page in the same file.
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* blkid tells us which block, posid tells us which entry in the linp
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* (ItemIdData) array we want.
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*/
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typedef struct ItemPointerData
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{
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BlockIdData ip_blkid;
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OffsetNumber ip_posid;
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1997-09-08 23:56:23 +02:00
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} ItemPointerData;
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1996-08-28 03:59:28 +02:00
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1997-09-07 07:04:48 +02:00
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typedef ItemPointerData *ItemPointer;
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1996-08-28 03:59:28 +02:00
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/* ----------------
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* support macros
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1996-08-28 03:59:28 +02:00
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* ----------------
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*/
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/*
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* ItemPointerIsValid --
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* True iff the disk item pointer is not NULL.
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1996-08-28 03:59:28 +02:00
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*/
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#define ItemPointerIsValid(pointer) \
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((bool) (PointerIsValid(pointer) && ((pointer)->ip_posid != 0)))
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/*
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* ItemPointerGetBlockNumber --
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* Returns the block number of a disk item pointer.
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*/
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#define ItemPointerGetBlockNumber(pointer) \
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(AssertMacro(ItemPointerIsValid(pointer)) ? \
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BlockIdGetBlockNumber(&(pointer)->ip_blkid) : (BlockNumber) 0)
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1996-08-28 03:59:28 +02:00
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/*
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* ItemPointerGetOffsetNumber --
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* Returns the offset number of a disk item pointer.
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1996-08-28 03:59:28 +02:00
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*/
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#define ItemPointerGetOffsetNumber(pointer) \
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(AssertMacro(ItemPointerIsValid(pointer)) ? \
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(pointer)->ip_posid : \
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InvalidOffsetNumber)
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/*
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* ItemPointerSet --
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* Sets a disk item pointer to the specified block and offset.
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1996-08-28 03:59:28 +02:00
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*/
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#define ItemPointerSet(pointer, blockNumber, offNum) \
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Assert(PointerIsValid(pointer)); \
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BlockIdSet(&((pointer)->ip_blkid), blockNumber); \
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(pointer)->ip_posid = offNum
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/*
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* ItemPointerSetBlockNumber --
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* Sets a disk item pointer to the specified block.
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*/
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#define ItemPointerSetBlockNumber(pointer, blockNumber) \
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Assert(PointerIsValid(pointer)); \
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BlockIdSet(&((pointer)->ip_blkid), blockNumber)
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/*
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* ItemPointerSetOffsetNumber --
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* Sets a disk item pointer to the specified offset.
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*/
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#define ItemPointerSetOffsetNumber(pointer, offsetNumber) \
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AssertMacro(PointerIsValid(pointer)); \
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(pointer)->ip_posid = (offsetNumber)
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/*
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* ItemPointerCopy --
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* Copies the contents of one disk item pointer to another.
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*/
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#define ItemPointerCopy(fromPointer, toPointer) \
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Assert(PointerIsValid(toPointer)); \
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Assert(PointerIsValid(fromPointer)); \
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*(toPointer) = *(fromPointer)
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/*
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* ItemPointerSetInvalid --
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* Sets a disk item pointer to be invalid.
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*/
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#define ItemPointerSetInvalid(pointer) \
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Assert(PointerIsValid(pointer)); \
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BlockIdSet(&((pointer)->ip_blkid), InvalidBlockNumber); \
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(pointer)->ip_posid = InvalidOffsetNumber
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1996-08-28 03:59:28 +02:00
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/* ----------------
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1997-09-07 07:04:48 +02:00
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* externs
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1996-08-28 03:59:28 +02:00
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* ----------------
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*/
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1997-09-08 04:41:22 +02:00
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extern bool ItemPointerEquals(ItemPointer pointer1, ItemPointer pointer2);
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1996-08-28 03:59:28 +02:00
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1997-09-07 07:04:48 +02:00
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#endif /* ITEMPTR_H */
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