htup.h

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

)

#define HeapTupleHeaderGetTypMod(tup) \
( \
	(tup)->t_choice.t_datum.datum_typmod \
)

#define HeapTupleHeaderSetTypMod(tup, typmod) \
( \
	(tup)->t_choice.t_datum.datum_typmod = (typmod) \
)

#define HeapTupleHeaderGetOid(tup) \
( \
	((tup)->t_infomask & HEAP_HASOID) ? \
		*((Oid *) ((char *)(tup) + (tup)->t_hoff - sizeof(Oid))) \
	: \
		InvalidOid \
)

#define HeapTupleHeaderSetOid(tup, oid) \
do { \
	Assert((tup)->t_infomask & HEAP_HASOID); \
	*((Oid *) ((char *)(tup) + (tup)->t_hoff - sizeof(Oid))) = (oid); \
} while (0)


/*
 * BITMAPLEN(NATTS) -
 *		Computes size of null bitmap given number of data columns.
 */
#define BITMAPLEN(NATTS)	(((int)(NATTS) + 7) / 8)

/*
 * MaxTupleSize is the maximum allowed size of a tuple, including header and
 * MAXALIGN alignment padding.	Basically it's BLCKSZ minus the other stuff
 * that has to be on a disk page.  The "other stuff" includes access-method-
 * dependent "special space", which we assume will be no more than
 * MaxSpecialSpace bytes (currently, on heap pages it's actually zero).
 *
 * NOTE: we do not need to count an ItemId for the tuple because
 * sizeof(PageHeaderData) includes the first ItemId on the page.
 */
#define MaxSpecialSpace  32

#define MaxTupleSize	\
	(BLCKSZ - MAXALIGN(sizeof(PageHeaderData) + MaxSpecialSpace))

/*
 * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
 * fit on one heap page.  (Note that indexes could have more, because they
 * use a smaller tuple header.)  We arrive at the divisor because each tuple
 * must be maxaligned, and it must have an associated item pointer.
 */
#define MaxHeapTuplesPerPage	\
	((int) ((BLCKSZ - offsetof(PageHeaderData, pd_linp)) / \
			(MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData))))

/*
 * MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
 * data fields of char(n) and similar types.  It need not have anything
 * directly to do with the *actual* upper limit of varlena values, which
 * is currently 1Gb (see struct varattrib in postgres.h).  I've set it
 * at 10Mb which seems like a reasonable number --- tgl 8/6/00.
 */
#define MaxAttrSize		(10 * 1024 * 1024)


/*
 * Attribute numbers for the system-defined attributes
 */
#define SelfItemPointerAttributeNumber			(-1)
#define ObjectIdAttributeNumber					(-2)
#define MinTransactionIdAttributeNumber			(-3)
#define MinCommandIdAttributeNumber				(-4)
#define MaxTransactionIdAttributeNumber			(-5)
#define MaxCommandIdAttributeNumber				(-6)
#define TableOidAttributeNumber					(-7)
#define FirstLowInvalidHeapAttributeNumber		(-8)


/*
 * HeapTupleData is an in-memory data structure that points to a tuple.
 *
 * There are several ways in which this data structure is used:
 *
 * * Pointer to a tuple in a disk buffer: t_data points directly into the
 *	 buffer (which the code had better be holding a pin on, but this is not
 *	 reflected in HeapTupleData itself).  t_datamcxt must be NULL.
 *
 * * Pointer to nothing: t_data and t_datamcxt are NULL.  This is used as
 *	 a failure indication in some functions.
 *
 * * Part of a palloc'd tuple: the HeapTupleData itself and the tuple
 *	 form a single palloc'd chunk.  t_data points to the memory location
 *	 immediately following the HeapTupleData struct (at offset HEAPTUPLESIZE),
 *	 and t_datamcxt is the containing context.	This is used as the output
 *	 format of heap_form_tuple and related routines.
 *
 * * Separately allocated tuple: t_data points to a palloc'd chunk that
 *	 is not adjacent to the HeapTupleData, and t_datamcxt is the context
 *	 containing that chunk.
 *
 * t_len should always be valid, except in the pointer-to-nothing case.
 * t_self and t_tableOid should be valid if the HeapTupleData points to
 * a disk buffer, or if it represents a copy of a tuple on disk.  They
 * should be explicitly set invalid in manufactured tuples.
 */
typedef struct HeapTupleData
{
	uint32		t_len;			/* length of *t_data */
	ItemPointerData t_self;		/* SelfItemPointer */
	Oid			t_tableOid;		/* table the tuple came from */
	MemoryContext t_datamcxt;	/* memory context of allocation */
	HeapTupleHeader t_data;		/* -> tuple header and data */
} HeapTupleData;

typedef HeapTupleData *HeapTuple;

#define HEAPTUPLESIZE	MAXALIGN(sizeof(HeapTupleData))

/*
 * GETSTRUCT - given a HeapTuple pointer, return address of the user data
 */
#define GETSTRUCT(TUP) ((char *) ((TUP)->t_data) + (TUP)->t_data->t_hoff)

/*
 * Accessor macros to be used with HeapTuple pointers.
 */
#define HeapTupleIsValid(tuple) PointerIsValid(tuple)

#define HeapTupleHasNulls(tuple) \
		(((tuple)->t_data->t_infomask & HEAP_HASNULL) != 0)

#define HeapTupleNoNulls(tuple) \
		(!((tuple)->t_data->t_infomask & HEAP_HASNULL))

#define HeapTupleHasVarWidth(tuple) \
		(((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH) != 0)

#define HeapTupleAllFixed(tuple) \
		(!((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH))

#define HeapTupleHasExternal(tuple) \
		(((tuple)->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)

#define HeapTupleHasCompressed(tuple) \
		(((tuple)->t_data->t_infomask & HEAP_HASCOMPRESSED) != 0)

#define HeapTupleHasExtended(tuple) \
		(((tuple)->t_data->t_infomask & HEAP_HASEXTENDED) != 0)

#define HeapTupleGetOid(tuple) \
		HeapTupleHeaderGetOid((tuple)->t_data)

#define HeapTupleSetOid(tuple, oid) \
		HeapTupleHeaderSetOid((tuple)->t_data, (oid))


/*
 * WAL record definitions for heapam.c's WAL operations
 *
 * XLOG allows to store some information in high 4 bits of log
 * record xl_info field.  We use 3 for opcode and one for init bit.
 */
#define XLOG_HEAP_INSERT	0x00
#define XLOG_HEAP_DELETE	0x10
#define XLOG_HEAP_UPDATE	0x20
#define XLOG_HEAP_MOVE		0x30
#define XLOG_HEAP_CLEAN		0x40
#define XLOG_HEAP_NEWPAGE	0x50
#define XLOG_HEAP_LOCK		0x60
/* opcode 0x70 still free */
#define XLOG_HEAP_OPMASK	0x70
/*
 * When we insert 1st item on new page in INSERT/UPDATE
 * we can (and we do) restore entire page in redo
 */
#define XLOG_HEAP_INIT_PAGE 0x80

/*
 * All what we need to find changed tuple
 *
 * NB: on most machines, sizeof(xl_heaptid) will include some trailing pad
 * bytes for alignment.  We don't want to store the pad space in the XLOG,
 * so use SizeOfHeapTid for space calculations.  Similar comments apply for
 * the other xl_FOO structs.
 */
typedef struct xl_heaptid
{
	RelFileNode node;
	ItemPointerData tid;		/* changed tuple id */
} xl_heaptid;

#define SizeOfHeapTid		(offsetof(xl_heaptid, tid) + SizeOfIptrData)

/* This is what we need to know about delete */
typedef struct xl_heap_delete
{
	xl_heaptid	target;			/* deleted tuple id */
} xl_heap_delete;

#define SizeOfHeapDelete	(offsetof(xl_heap_delete, target) + SizeOfHeapTid)

/*
 * We don't store the whole fixed part (HeapTupleHeaderData) of an inserted
 * or updated tuple in WAL; we can save a few bytes by reconstructing the
 * fields that are available elsewhere in the WAL record, or perhaps just
 * plain needn't be reconstructed.  These are the fields we must store.
 * NOTE: t_hoff could be recomputed, but we may as well store it because
 * it will come for free due to alignment considerations.
 */
typedef struct xl_heap_header
{
	int16		t_natts;
	uint16		t_infomask;
	uint8		t_hoff;
} xl_heap_header;

#define SizeOfHeapHeader	(offsetof(xl_heap_header, t_hoff) + sizeof(uint8))

/* This is what we need to know about insert */
typedef struct xl_heap_insert
{
	xl_heaptid	target;			/* inserted tuple id */
	/* xl_heap_header & TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_heap_insert;

#define SizeOfHeapInsert	(offsetof(xl_heap_insert, target) + SizeOfHeapTid)

/* This is what we need to know about update|move */
typedef struct xl_heap_update
{
	xl_heaptid	target;			/* deleted tuple id */
	ItemPointerData newtid;		/* new inserted tuple id */
	/* NEW TUPLE xl_heap_header (PLUS xmax & xmin IF MOVE OP) */
	/* and TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_heap_update;

#define SizeOfHeapUpdate	(offsetof(xl_heap_update, newtid) + SizeOfIptrData)

/* This is what we need to know about vacuum page cleanup */
typedef struct xl_heap_clean
{
	RelFileNode node;
	BlockNumber block;
	/* UNUSED OFFSET NUMBERS FOLLOW AT THE END */
} xl_heap_clean;

#define SizeOfHeapClean (offsetof(xl_heap_clean, block) + sizeof(BlockNumber))

/* This is for replacing a page's contents in toto */
/* NB: this is used for indexes as well as heaps */
typedef struct xl_heap_newpage
{
	RelFileNode node;
	BlockNumber blkno;			/* location of new page */
	/* entire page contents follow at end of record */
} xl_heap_newpage;

#define SizeOfHeapNewpage	(offsetof(xl_heap_newpage, blkno) + sizeof(BlockNumber))

/* This is what we need to know about lock */
typedef struct xl_heap_lock
{
	xl_heaptid	target;			/* locked tuple id */
	TransactionId locking_xid;	/* might be a MultiXactId not xid */
	bool		xid_is_mxact;	/* is it? */
	bool		shared_lock;	/* shared or exclusive row lock? */
} xl_heap_lock;

#define SizeOfHeapLock	(offsetof(xl_heap_lock, shared_lock) + sizeof(bool))

#endif   /* HTUP_H */