1 /*-------------------------------------------------------------------------
4 * general index access method routines
6 * Copyright (c) 1994, Regents of the University of California
10 * $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.35 1999/07/16 04:58:28 momjian Exp $
13 * index_open - open an index relation by relationId
14 * index_openr - open a index relation by name
15 * index_close - close a index relation
16 * index_beginscan - start a scan of an index
17 * index_rescan - restart a scan of an index
18 * index_endscan - end a scan
19 * index_insert - insert an index tuple into a relation
20 * index_delete - delete an item from an index relation
21 * index_markpos - mark a scan position
22 * index_restrpos - restore a scan position
23 * index_getnext - get the next tuple from a scan
24 * ** index_fetch - retrieve tuple with tid
25 * ** index_replace - replace a tuple
26 * ** index_getattr - get an attribute from an index tuple
27 * index_getprocid - get a support procedure id from the rel tuple
29 * IndexScanIsValid - check index scan
32 * This file contains the index_ routines which used
33 * to be a scattered collection of stuff in access/genam.
35 * The ** routines: index_fetch, index_replace, and index_getattr
36 * have not yet been implemented. They may not be needed.
39 * Scans are implemented as follows:
41 * `0' represents an invalid item pointer.
42 * `-' represents an unknown item pointer.
43 * `X' represents a known item pointers.
44 * `+' represents known or invalid item pointers.
45 * `*' represents any item pointers.
47 * State is represented by a triple of these symbols in the order of
48 * previous, current, next. Note that the case of reverse scans works
52 * (1) + + - + 0 0 (if the next item pointer is invalid)
53 * (2) + X - (otherwise)
54 * (3) * 0 0 * 0 0 (no change)
55 * (4) + X 0 X 0 0 (shift)
56 * (5) * + X + X - (shift, add unknown)
58 * All other states cannot occur.
60 * Note: It would be possible to cache the status of the previous and
61 * next item pointer using the flags.
63 *-------------------------------------------------------------------------
68 #include "access/genam.h"
69 #include "access/heapam.h"
70 #include "utils/relcache.h"
73 * undefine macros we aren't going to use that would otherwise
74 * get in our way.. delete is defined in c.h and the am's are
88 /* ----------------------------------------------------------------
89 * macros used in index_ routines
90 * ----------------------------------------------------------------
92 #define RELATION_CHECKS \
94 AssertMacro(RelationIsValid(relation)), \
95 AssertMacro(PointerIsValid(relation->rd_am)) \
100 AssertMacro(IndexScanIsValid(scan)), \
101 AssertMacro(RelationIsValid(scan->relation)), \
102 AssertMacro(PointerIsValid(scan->relation->rd_am)) \
105 #define GET_REL_PROCEDURE(x,y) \
107 procedure = relation->rd_am->y, \
108 (!RegProcedureIsValid(procedure)) ? \
109 elog(ERROR, "index_%s: invalid %s regproc", \
110 CppAsString(x), CppAsString(y)) \
114 #define GET_SCAN_PROCEDURE(x,y) \
116 procedure = scan->relation->rd_am->y, \
117 (!RegProcedureIsValid(procedure)) ? \
118 elog(ERROR, "index_%s: invalid %s regproc", \
119 CppAsString(x), CppAsString(y)) \
124 /* ----------------------------------------------------------------
125 * index_ interface functions
126 * ----------------------------------------------------------------
129 * index_open - open an index relation by relationId
131 * presently the relcache routines do all the work we need
132 * to open/close index relations.
136 index_open(Oid relationId)
138 return RelationIdGetRelation(relationId);
142 * index_openr - open a index relation by name
144 * presently the relcache routines do all the work we need
145 * to open/close index relations.
149 index_openr(char *relationName)
151 return RelationNameGetRelation(relationName);
155 * index_close - close a index relation
157 * presently the relcache routines do all the work we need
158 * to open/close index relations.
162 index_close(Relation relation)
164 RelationClose(relation);
168 * index_insert - insert an index tuple into a relation
172 index_insert(Relation relation,
175 ItemPointer heap_t_ctid,
178 RegProcedure procedure;
179 InsertIndexResult specificResult;
182 GET_REL_PROCEDURE(insert, aminsert);
185 * have the am's insert proc do all the work.
188 specificResult = (InsertIndexResult)
189 fmgr(procedure, relation, datum, nulls, heap_t_ctid, heapRel, NULL);
191 /* must be pfree'ed */
192 return specificResult;
196 * index_delete - delete an item from an index relation
200 index_delete(Relation relation, ItemPointer indexItem)
202 RegProcedure procedure;
205 GET_REL_PROCEDURE(delete, amdelete);
207 fmgr(procedure, relation, indexItem);
211 * index_beginscan - start a scan of an index
215 index_beginscan(Relation relation,
220 IndexScanDesc scandesc;
221 RegProcedure procedure;
224 GET_REL_PROCEDURE(beginscan, ambeginscan);
226 LockRelation(relation, AccessShareLock);
228 scandesc = (IndexScanDesc)
229 fmgr(procedure, relation, scanFromEnd, numberOfKeys, key);
235 * index_rescan - restart a scan of an index
239 index_rescan(IndexScanDesc scan, bool scanFromEnd, ScanKey key)
241 RegProcedure procedure;
244 GET_SCAN_PROCEDURE(rescan, amrescan);
246 fmgr(procedure, scan, scanFromEnd, key);
250 * index_endscan - end a scan
254 index_endscan(IndexScanDesc scan)
256 RegProcedure procedure;
259 GET_SCAN_PROCEDURE(endscan, amendscan);
261 fmgr(procedure, scan);
263 UnlockRelation(scan->relation, AccessShareLock);
267 * index_markpos - mark a scan position
271 index_markpos(IndexScanDesc scan)
273 RegProcedure procedure;
276 GET_SCAN_PROCEDURE(markpos, ammarkpos);
278 fmgr(procedure, scan);
282 * index_restrpos - restore a scan position
286 index_restrpos(IndexScanDesc scan)
288 RegProcedure procedure;
291 GET_SCAN_PROCEDURE(restrpos, amrestrpos);
293 fmgr(procedure, scan);
297 * index_getnext - get the next tuple from a scan
299 * A RetrieveIndexResult is a index tuple/heap tuple pair
303 index_getnext(IndexScanDesc scan,
304 ScanDirection direction)
306 RegProcedure procedure;
307 RetrieveIndexResult result;
310 GET_SCAN_PROCEDURE(getnext, amgettuple);
313 * have the am's gettuple proc do all the work.
316 result = (RetrieveIndexResult) fmgr(procedure, scan, direction);
324 * Some indexed access methods may require support routines that are
325 * not in the operator class/operator model imposed by pg_am. These
326 * access methods may store the OIDs of registered procedures they
327 * need in pg_amproc. These registered procedure OIDs are ordered in
328 * a way that makes sense to the access method, and used only by the
329 * access method. The general index code doesn't know anything about
330 * the routines involved; it just builds an ordered list of them for
331 * each attribute on which an index is defined.
333 * This routine returns the requested procedure OID for a particular
338 index_getprocid(Relation irel,
345 natts = irel->rd_rel->relnatts;
347 loc = irel->rd_support;
351 return loc[(natts * (procnum - 1)) + (attnum - 1)];
355 GetIndexValue(HeapTuple tuple,
358 AttrNumber *attrNums,
359 FuncIndexInfo *fInfo,
365 if (PointerIsValid(fInfo) && FIgetProcOid(fInfo) != InvalidOid)
368 Datum *attData = (Datum *) palloc(FIgetnArgs(fInfo) * sizeof(Datum));
370 for (i = 0; i < FIgetnArgs(fInfo); i++)
372 attData[i] = heap_getattr(tuple,
379 returnVal = (Datum) fmgr_array_args(FIgetProcOid(fInfo),
387 returnVal = heap_getattr(tuple, attrNums[attOff], hTupDesc, attNull);