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2ff501590b
Also performed an initial run through of upgrading our Copyright date to extend to 2005 ... first run here was very simple ... change everything where: grep 1996-2004 && the word 'Copyright' ... scanned through the generated list with 'less' first, and after, to make sure that I only picked up the right entries ...
121 lines
3.3 KiB
C
121 lines
3.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* block.h
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* POSTGRES disk block definitions.
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*
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*
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* Portions Copyright (c) 1996-2005, 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/storage/block.h,v 1.21 2004/12/31 22:03:42 pgsql Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef BLOCK_H
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#define BLOCK_H
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/*
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* BlockNumber:
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*
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* each data file (heap or index) is divided into postgres disk blocks
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* (which may be thought of as the unit of i/o -- a postgres buffer
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* contains exactly one disk block). the blocks are numbered
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* sequentially, 0 to 0xFFFFFFFE.
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*
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* InvalidBlockNumber is the same thing as P_NEW in buf.h.
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*
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* the access methods, the buffer manager and the storage manager are
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* more or less the only pieces of code that should be accessing disk
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* blocks directly.
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*/
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typedef uint32 BlockNumber;
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#define InvalidBlockNumber ((BlockNumber) 0xFFFFFFFF)
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#define MaxBlockNumber ((BlockNumber) 0xFFFFFFFE)
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/*
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* BlockId:
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*
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* this is a storage type for BlockNumber. in other words, this type
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* is used for on-disk structures (e.g., in HeapTupleData) whereas
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* BlockNumber is the type on which calculations are performed (e.g.,
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* in access method code).
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*
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* there doesn't appear to be any reason to have separate types except
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* for the fact that BlockIds can be SHORTALIGN'd (and therefore any
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* structures that contains them, such as ItemPointerData, can also be
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* SHORTALIGN'd). this is an important consideration for reducing the
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* space requirements of the line pointer (ItemIdData) array on each
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* page and the header of each heap or index tuple, so it doesn't seem
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* wise to change this without good reason.
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*/
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typedef struct BlockIdData
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{
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uint16 bi_hi;
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uint16 bi_lo;
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} BlockIdData;
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typedef BlockIdData *BlockId; /* block identifier */
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/* ----------------
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* support macros
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* ----------------
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*/
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/*
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* BlockNumberIsValid
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* True iff blockNumber is valid.
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*/
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#define BlockNumberIsValid(blockNumber) \
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((bool) ((BlockNumber) (blockNumber) != InvalidBlockNumber))
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/*
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* BlockIdIsValid
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* True iff the block identifier is valid.
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*/
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#define BlockIdIsValid(blockId) \
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((bool) PointerIsValid(blockId))
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/*
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* BlockIdSet
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* Sets a block identifier to the specified value.
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*/
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#define BlockIdSet(blockId, blockNumber) \
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( \
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AssertMacro(PointerIsValid(blockId)), \
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(blockId)->bi_hi = (blockNumber) >> 16, \
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(blockId)->bi_lo = (blockNumber) & 0xffff \
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)
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/*
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* BlockIdCopy
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* Copy a block identifier.
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*/
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#define BlockIdCopy(toBlockId, fromBlockId) \
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( \
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AssertMacro(PointerIsValid(toBlockId)), \
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AssertMacro(PointerIsValid(fromBlockId)), \
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(toBlockId)->bi_hi = (fromBlockId)->bi_hi, \
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(toBlockId)->bi_lo = (fromBlockId)->bi_lo \
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)
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/*
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* BlockIdEquals
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* Check for block number equality.
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*/
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#define BlockIdEquals(blockId1, blockId2) \
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((blockId1)->bi_hi == (blockId2)->bi_hi && \
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(blockId1)->bi_lo == (blockId2)->bi_lo)
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/*
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* BlockIdGetBlockNumber
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* Retrieve the block number from a block identifier.
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*/
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#define BlockIdGetBlockNumber(blockId) \
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( \
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AssertMacro(BlockIdIsValid(blockId)), \
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(BlockNumber) (((blockId)->bi_hi << 16) | ((uint16) (blockId)->bi_lo)) \
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)
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#endif /* BLOCK_H */
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