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/*------------------------------------------------------------------------- * * relscan.h * POSTGRES relation scan descriptor definitions. * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/access/relscan.h * *------------------------------------------------------------------------- */ #ifndef RELSCAN_H #define RELSCAN_H #include "access/genam.h" #include "access/heapam.h" #include "access/itup.h" #include "access/tupdesc.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 */ bool rs_bitmapscan; /* true if this is really a bitmap scan */ bool rs_pageatatime; /* verify visibility page-at-a-time? */ bool rs_allow_strat; /* allow or disallow use of access strategy */ bool rs_allow_sync; /* allow or disallow use of syncscan */ /* state set up at initscan time */ BlockNumber rs_nblocks; /* number of blocks to scan */ BlockNumber rs_startblock; /* block # to start at */ BufferAccessStrategy rs_strategy; /* access strategy for reads */ bool rs_syncscan; /* report location to syncscan logic? */ /* scan current state */ bool rs_inited; /* false = scan not init'd yet */ HeapTupleData rs_ctup; /* current tuple in scan, if any */ BlockNumber rs_cblock; /* current block # 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 */ /* these fields only used in page-at-a-time mode and for bitmap scans */ int rs_cindex; /* current tuple's index in vistuples */ int rs_mindex; /* marked tuple's saved index */ int rs_ntuples; /* number of visible tuples on page */ OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */ } HeapScanDescData; /* * We use the same IndexScanDescData structure for both amgettuple-based * and amgetbitmap-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 index qualifier conditions */ int numberOfOrderBys; /* number of ordering operators */ ScanKey keyData; /* array of index qualifier descriptors */ ScanKey orderByData; /* array of ordering op descriptors */ bool xs_want_itup; /* caller requests index tuples */ /* 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 */ bool xactStartedInRecovery; /* prevents killing/seeing killed * tuples */ /* index access method's private state */ void *opaque; /* access-method-specific info */ /* in an index-only scan, this is valid after a successful amgettuple */ IndexTuple xs_itup; /* index tuple returned by AM */ TupleDesc xs_itupdesc; /* rowtype descriptor of xs_itup */ /* xs_ctup/xs_cbuf/xs_recheck are valid after a successful index_getnext */ 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 */ bool xs_recheck; /* T means scan keys must be rechecked */ /* state data for traversing HOT chains in index_getnext */ bool xs_continue_hot; /* T if must keep walking HOT chain */ } IndexScanDescData; /* Struct for heap-or-index scans of system tables */ typedef struct SysScanDescData { Relation heap_rel; /* catalog being scanned */ Relation irel; /* NULL if doing heap scan */ HeapScanDesc scan; /* only valid in heap-scan case */ IndexScanDesc iscan; /* only valid in index-scan case */ } SysScanDescData; #endif /* RELSCAN_H */