1 /*-------------------------------------------------------------------------
4 * POSTGRES relation scan descriptor definitions.
7 * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
10 * src/include/access/relscan.h
12 *-------------------------------------------------------------------------
17 #include "access/genam.h"
18 #include "access/heapam.h"
19 #include "access/htup_details.h"
20 #include "access/itup.h"
21 #include "access/tupdesc.h"
24 typedef struct HeapScanDescData
27 Relation rs_rd; /* heap relation descriptor */
28 Snapshot rs_snapshot; /* snapshot to see */
29 int rs_nkeys; /* number of scan keys */
30 ScanKey rs_key; /* array of scan key descriptors */
31 bool rs_bitmapscan; /* true if this is really a bitmap scan */
32 bool rs_pageatatime; /* verify visibility page-at-a-time? */
33 bool rs_allow_strat; /* allow or disallow use of access strategy */
34 bool rs_allow_sync; /* allow or disallow use of syncscan */
35 bool rs_temp_snap; /* unregister snapshot at scan end? */
37 /* state set up at initscan time */
38 BlockNumber rs_nblocks; /* number of blocks to scan */
39 BlockNumber rs_startblock; /* block # to start at */
40 BufferAccessStrategy rs_strategy; /* access strategy for reads */
41 bool rs_syncscan; /* report location to syncscan logic? */
43 /* scan current state */
44 bool rs_inited; /* false = scan not init'd yet */
45 HeapTupleData rs_ctup; /* current tuple in scan, if any */
46 BlockNumber rs_cblock; /* current block # in scan, if any */
47 Buffer rs_cbuf; /* current buffer in scan, if any */
48 /* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
49 ItemPointerData rs_mctid; /* marked scan position, if any */
51 /* these fields only used in page-at-a-time mode and for bitmap scans */
52 int rs_cindex; /* current tuple's index in vistuples */
53 int rs_mindex; /* marked tuple's saved index */
54 int rs_ntuples; /* number of visible tuples on page */
55 OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */
59 * We use the same IndexScanDescData structure for both amgettuple-based
60 * and amgetbitmap-based index scans. Some fields are only relevant in
61 * amgettuple-based scans.
63 typedef struct IndexScanDescData
66 Relation heapRelation; /* heap relation descriptor, or NULL */
67 Relation indexRelation; /* index relation descriptor */
68 Snapshot xs_snapshot; /* snapshot to see */
69 int numberOfKeys; /* number of index qualifier conditions */
70 int numberOfOrderBys; /* number of ordering operators */
71 ScanKey keyData; /* array of index qualifier descriptors */
72 ScanKey orderByData; /* array of ordering op descriptors */
73 bool xs_want_itup; /* caller requests index tuples */
75 /* signaling to index AM about killing index tuples */
76 bool kill_prior_tuple; /* last-returned tuple is dead */
77 bool ignore_killed_tuples; /* do not return killed entries */
78 bool xactStartedInRecovery; /* prevents killing/seeing killed
81 /* index access method's private state */
82 void *opaque; /* access-method-specific info */
84 /* in an index-only scan, this is valid after a successful amgettuple */
85 IndexTuple xs_itup; /* index tuple returned by AM */
86 TupleDesc xs_itupdesc; /* rowtype descriptor of xs_itup */
88 /* xs_ctup/xs_cbuf/xs_recheck are valid after a successful index_getnext */
89 HeapTupleData xs_ctup; /* current heap tuple, if any */
90 Buffer xs_cbuf; /* current heap buffer in scan, if any */
91 /* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
92 bool xs_recheck; /* T means scan keys must be rechecked */
94 /* state data for traversing HOT chains in index_getnext */
95 bool xs_continue_hot; /* T if must keep walking HOT chain */
98 /* Struct for heap-or-index scans of system tables */
99 typedef struct SysScanDescData
101 Relation heap_rel; /* catalog being scanned */
102 Relation irel; /* NULL if doing heap scan */
103 HeapScanDesc scan; /* only valid in heap-scan case */
104 IndexScanDesc iscan; /* only valid in index-scan case */
105 Snapshot snapshot; /* snapshot to unregister at end of scan */
108 #endif /* RELSCAN_H */