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/*-------------------------------------------------------------------------
*
* relscan.h
* POSTGRES relation scan descriptor definitions.
*
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.40 2005/10/07 14:55:35 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef RELSCAN_H
#define RELSCAN_H
#include "access/skey.h"
#include "utils/tqual.h"
typedef struct HeapScanDescData
{
/* scan parameters */
Relation rs_rd; /* heap relation descriptor */
Snapshot rs_snapshot; /* snapshot to see */
int rs_nkeys; /* number of scan keys */
ScanKey rs_key; /* array of scan key descriptors */
BlockNumber rs_nblocks; /* number of blocks to scan */
/* scan current state */
HeapTupleData rs_ctup; /* current tuple in scan, if any */
Buffer rs_cbuf; /* current buffer in scan, if any */
/* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
ItemPointerData rs_mctid; /* marked scan position, if any */
PgStat_Info rs_pgstat_info; /* statistics collector hook */
} HeapScanDescData;
typedef HeapScanDescData *HeapScanDesc;
/*
* We use the same IndexScanDescData structure for both amgettuple-based
* and amgetmulti-based index scans. Some fields are only relevant in
* amgettuple-based scans.
*/
typedef struct IndexScanDescData
{
/* scan parameters */
Relation heapRelation; /* heap relation descriptor, or NULL */
Relation indexRelation; /* index relation descriptor */
Snapshot xs_snapshot; /* snapshot to see */
int numberOfKeys; /* number of scan keys */
ScanKey keyData; /* array of scan key descriptors */
bool is_multiscan; /* TRUE = using amgetmulti */
/* signaling to index AM about killing index tuples */
bool kill_prior_tuple; /* last-returned tuple is dead */
bool ignore_killed_tuples; /* do not return killed entries */
/* set by index AM if scan keys satisfy index's uniqueness constraint */
bool keys_are_unique;
/* scan current state */
bool got_tuple; /* true after successful index_getnext */
void *opaque; /* access-method-specific info */
ItemPointerData currentItemData; /* current index pointer */
ItemPointerData currentMarkData; /* marked position, if any */
/*
* xs_ctup/xs_cbuf are valid after a successful index_getnext. After
* index_getnext_indexitem, xs_ctup.t_self contains the heap tuple TID
* from the index entry, but its other fields are not valid.
*/
HeapTupleData xs_ctup; /* current heap tuple, if any */
Buffer xs_cbuf; /* current heap buffer in scan, if any */
/* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
/*
* If keys_are_unique and got_tuple are both true, we stop calling the
* index AM; it is then necessary for index_getnext to keep track of
* the logical scan position for itself. It does that using
* unique_tuple_pos: -1 = before row, 0 = on row, +1 = after row.
*/
int unique_tuple_pos; /* logical position */
int unique_tuple_mark; /* logical marked position */
PgStat_Info xs_pgstat_info; /* statistics collector hook */
} IndexScanDescData;
typedef IndexScanDescData *IndexScanDesc;
/*
* 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 */
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