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 * genam.h
 *      POSTGRES generalized index access method definitions.
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 * $PostgreSQL$
#ifndef GENAM_H
#define GENAM_H

#include "access/sdir.h"
#include "access/skey.h"
#include "nodes/tidbitmap.h"
#include "storage/buf.h"
#include "storage/lock.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"

 * Struct for statistics returned by ambuild
typedef struct IndexBuildResult
      double            heap_tuples;      /* # of tuples seen in parent table */
      double            index_tuples;     /* # of tuples inserted into index */
} IndexBuildResult;

 * Struct for input arguments passed to ambulkdelete and amvacuumcleanup
 * Note that num_heap_tuples will not be valid during ambulkdelete,
 * only amvacuumcleanup.
typedef struct IndexVacuumInfo
      Relation    index;                  /* the index being vacuumed */
      bool        vacuum_full;      /* VACUUM FULL (we have exclusive lock) */
      bool        analyze_only;     /* ANALYZE (without any actual vacuum) */
      int               message_level;    /* ereport level for progress messages */
      double            num_heap_tuples;  /* tuples remaining in heap */
      BufferAccessStrategy strategy;            /* access strategy for reads */
} IndexVacuumInfo;

 * Struct for statistics returned by ambulkdelete and amvacuumcleanup
 * This struct is normally allocated by the first ambulkdelete call and then
 * passed along through subsequent ones until amvacuumcleanup; however,
 * amvacuumcleanup must be prepared to allocate it in the case where no
 * ambulkdelete calls were made (because no tuples needed deletion).
 * Note that an index AM could choose to return a larger struct
 * of which this is just the first field; this provides a way for ambulkdelete
 * to communicate additional private data to amvacuumcleanup.
 * Note: pages_removed is the amount by which the index physically shrank,
 * if any (ie the change in its total size on disk).  pages_deleted and
 * pages_free refer to free space within the index file.
typedef struct IndexBulkDeleteResult
      BlockNumber num_pages;        /* pages remaining in index */
      BlockNumber pages_removed;    /* # removed during vacuum operation */
      double            num_index_tuples;       /* tuples remaining */
      double            tuples_removed; /* # removed during vacuum operation */
      BlockNumber pages_deleted;    /* # unused pages in index */
      BlockNumber pages_free;       /* # pages available for reuse */
} IndexBulkDeleteResult;

/* Typedef for callback function to determine if a tuple is bulk-deletable */
typedef bool (*IndexBulkDeleteCallback) (ItemPointer itemptr, void *state);

/* struct definitions appear in relscan.h */
typedef struct IndexScanDescData *IndexScanDesc;
typedef struct SysScanDescData *SysScanDesc;

 * generalized index_ interface routines (in indexam.c)

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

extern Relation index_open(Oid relationId, LOCKMODE lockmode);
extern void index_close(Relation relation, LOCKMODE lockmode);

extern bool index_insert(Relation indexRelation,
                   Datum *values, bool *isnull,
                   ItemPointer heap_t_ctid,
                   Relation heapRelation,
                   bool check_uniqueness);

extern IndexScanDesc index_beginscan(Relation heapRelation,
                        Relation indexRelation,
                        Snapshot snapshot,
                        int nkeys, ScanKey key);
extern IndexScanDesc index_beginscan_bitmap(Relation indexRelation,
                                Snapshot snapshot,
                                int nkeys, ScanKey key);
extern void index_rescan(IndexScanDesc scan, ScanKey key);
extern void index_endscan(IndexScanDesc scan);
extern void index_markpos(IndexScanDesc scan);
extern void index_restrpos(IndexScanDesc scan);
extern HeapTuple index_getnext(IndexScanDesc scan, ScanDirection direction);
extern int64 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap);

extern IndexBulkDeleteResult *index_bulk_delete(IndexVacuumInfo *info,
                          IndexBulkDeleteResult *stats,
                          IndexBulkDeleteCallback callback,
                          void *callback_state);
extern IndexBulkDeleteResult *index_vacuum_cleanup(IndexVacuumInfo *info,
                               IndexBulkDeleteResult *stats);
extern RegProcedure index_getprocid(Relation irel, AttrNumber attnum,
                        uint16 procnum);
extern FmgrInfo *index_getprocinfo(Relation irel, AttrNumber attnum,
                          uint16 procnum);

 * index access method support routines (in genam.c)
extern IndexScanDesc RelationGetIndexScan(Relation indexRelation,
                               int nkeys, ScanKey key);
extern void IndexScanEnd(IndexScanDesc scan);

 * heap-or-index access to system catalogs (in genam.c)
extern SysScanDesc systable_beginscan(Relation heapRelation,
                           Oid indexId,
                           bool indexOK,
                           Snapshot snapshot,
                           int nkeys, ScanKey key);
extern HeapTuple systable_getnext(SysScanDesc sysscan);
extern bool systable_recheck_tuple(SysScanDesc sysscan, HeapTuple tup);
extern void systable_endscan(SysScanDesc sysscan);
extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
                                                                    Relation indexRelation,
                                                                    Snapshot snapshot,
                                                                    int nkeys, ScanKey key);
extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
                                                              ScanDirection direction);
extern void systable_endscan_ordered(SysScanDesc sysscan);

#endif   /* GENAM_H */

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