/*-------------------------------------------------------------------------
*
* relscan.h
- * POSTGRES internal relation scan descriptor definitions.
+ * POSTGRES relation scan descriptor definitions.
*
*
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: relscan.h,v 1.24 2001/10/28 06:25:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.36 2004/08/29 04:13:03 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef RELSCAN_H
#define RELSCAN_H
+#include "access/skey.h"
#include "utils/tqual.h"
typedef struct HeapScanDescData
{
- Relation rs_rd; /* pointer to relation descriptor */
+ /* 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 tid, if any */
- Snapshot rs_snapshot; /* snapshot to see */
- uint16 rs_nkeys; /* number of scan keys to select tuples */
- ScanKey rs_key; /* key descriptors */
+ ItemPointerData rs_mctid; /* marked scan position, if any */
PgStat_Info rs_pgstat_info; /* statistics collector hook */
} HeapScanDescData;
typedef HeapScanDescData *HeapScanDesc;
+
typedef struct IndexScanDescData
{
- Relation relation; /* relation descriptor */
+ /* 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 */
+
+ /* 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 current pointer */
- uint8 flags; /* scan position flags */
- bool scanFromEnd; /* restart scan at end? */
- uint16 numberOfKeys; /* number of scan keys to select tuples */
- ScanKey keyData; /* key descriptors */
- FmgrInfo fn_getnext; /* cached lookup info for am's getnext fn */
+ 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 */
+
+ FmgrInfo fn_getnext; /* cached lookup info for AM's getnext fn */
+
+ /*
+ * 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;
-/* IndexScanDesc flag bits (none of these are actually used currently) */
-#define ScanUnmarked 0x01
-#define ScanUncheckedPrevious 0x02
-#define ScanUncheckedNext 0x04
-
/* ----------------
* IndexScanDescPtr is used in the executor where we have to
*/
#define IndexScanIsValid(scan) PointerIsValid(scan)
-#endif /* RELSCAN_H */
+#endif /* RELSCAN_H */