relscan.h

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * relscan.h
 *	  POSTGRES internal relation scan descriptor definitions.
 *
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 * $Id: relscan.h,v 1.15 1999/05/25 16:13:33 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef RELSCAN_H
#define RELSCAN_H

#include <storage/buf.h>
#include <utils/rel.h>
#include <access/htup.h>
#include <utils/tqual.h>

typedef ItemPointerData MarkData;

typedef struct HeapScanDescData
{
	Relation	rs_rd;			/* pointer to relation descriptor */
	HeapTupleData rs_ptup;		/* previous tuple in scan */
	HeapTupleData rs_ctup;		/* current tuple in scan */
	HeapTupleData rs_ntup;		/* next tuple in scan */
	Buffer		rs_pbuf;		/* previous buffer in scan */
	Buffer		rs_cbuf;		/* current buffer in scan */
	Buffer		rs_nbuf;		/* next buffer in scan */
	ItemPointerData rs_mptid;	/* marked previous tid */
	ItemPointerData rs_mctid;	/* marked current tid */
	ItemPointerData rs_mntid;	/* marked next tid */
	ItemPointerData rs_mcd;		/* marked current delta XXX ??? */
	Snapshot	rs_snapshot;	/* snapshot to see */
	bool		rs_atend;		/* restart scan at end? */
	uint16		rs_cdelta;		/* current delta in chain */
	uint16		rs_nkeys;		/* number of attributes in keys */
	ScanKey		rs_key;			/* key descriptors */
} HeapScanDescData;

typedef HeapScanDescData *HeapScanDesc;

typedef struct IndexScanDescData
{
	Relation	relation;		/* relation descriptor */
	void	   *opaque;			/* am-specific slot */
	ItemPointerData previousItemData;	/* previous index pointer */
	ItemPointerData currentItemData;	/* current index pointer */
	ItemPointerData nextItemData;		/* next index pointer */
	MarkData	previousMarkData;		/* marked previous pointer */
	MarkData	currentMarkData;/* marked current  pointer */
	MarkData	nextMarkData;	/* marked next pointer */
	uint8		flags;			/* scan position flags */
	bool		scanFromEnd;	/* restart scan at end? */
	uint16		numberOfKeys;	/* number of key attributes */
	ScanKey		keyData;		/* key descriptor */
} IndexScanDescData;

typedef IndexScanDescData *IndexScanDesc;

/* ----------------
 *		IndexScanDescPtr is used in the executor where we have to
 *		keep track of several index scans when using several indices
 *		- cim 9/10/89
 * ----------------
 */
typedef IndexScanDesc *IndexScanDescPtr;

/*
 * HeapScanIsValid
 *		True iff the heap scan is valid.
 */
#define HeapScanIsValid(scan) PointerIsValid(scan)

/*
 * IndexScanIsValid
 *		True iff the index scan is valid.
 */
#define IndexScanIsValid(scan) PointerIsValid(scan)

#endif	 /* RELSCAN_H */