granicus.if.org Git - postgresql/blob - src/backend/access/index/indexam.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * indexam.c
   4  *        general index access method routines
   5  *
   6  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.43 2000/05/28 17:55:52 tgl Exp $
  12  *
  13  * INTERFACE ROUTINES
  14  *              index_open              - open an index relation by relationId
  15  *              index_openr             - open a index relation by name
  16  *              index_close             - close a index relation
  17  *              index_beginscan - start a scan of an index
  18  *              index_rescan    - restart a scan of an index
  19  *              index_endscan   - end a scan
  20  *              index_insert    - insert an index tuple into a relation
  21  *              index_delete    - delete an item from an index relation
  22  *              index_markpos   - mark a scan position
  23  *              index_restrpos  - restore a scan position
  24  *              index_getnext   - get the next tuple from a scan
  25  * **   index_fetch             - retrieve tuple with tid
  26  * **   index_replace   - replace a tuple
  27  * **   index_getattr   - get an attribute from an index tuple
  28  *              index_getprocid - get a support procedure id from the rel tuple
  29  *
  30  *              IndexScanIsValid - check index scan
  31  *
  32  * NOTES
  33  *              This file contains the index_ routines which used
  34  *              to be a scattered collection of stuff in access/genam.
  35  *
  36  *              The ** routines: index_fetch, index_replace, and index_getattr
  37  *              have not yet been implemented.  They may not be needed.
  38  *
  39  * old comments
  40  *              Scans are implemented as follows:
  41  *
  42  *              `0' represents an invalid item pointer.
  43  *              `-' represents an unknown item pointer.
  44  *              `X' represents a known item pointers.
  45  *              `+' represents known or invalid item pointers.
  46  *              `*' represents any item pointers.
  47  *
  48  *              State is represented by a triple of these symbols in the order of
  49  *              previous, current, next.  Note that the case of reverse scans works
  50  *              identically.
  51  *
  52  *                              State   Result
  53  *              (1)             + + -   + 0 0                   (if the next item pointer is invalid)
  54  *              (2)                             + X -                   (otherwise)
  55  *              (3)             * 0 0   * 0 0                   (no change)
  56  *              (4)             + X 0   X 0 0                   (shift)
  57  *              (5)             * + X   + X -                   (shift, add unknown)
  58  *
  59  *              All other states cannot occur.
  60  *
  61  *              Note: It would be possible to cache the status of the previous and
  62  *                        next item pointer using the flags.
  63  *
  64  *-------------------------------------------------------------------------
  65  */
  66
  67 #include "postgres.h"
  68
  69 #include "access/genam.h"
  70 #include "access/heapam.h"
  71 #include "utils/relcache.h"
  72
  73
  74 /* ----------------------------------------------------------------
  75  *                                      macros used in index_ routines
  76  * ----------------------------------------------------------------
  77  */
  78 #define RELATION_CHECKS \
  79 ( \
  80         AssertMacro(RelationIsValid(relation)), \
  81         AssertMacro(PointerIsValid(relation->rd_am)) \
  82 )
  83
  84 #define SCAN_CHECKS \
  85 ( \
  86         AssertMacro(IndexScanIsValid(scan)), \
  87         AssertMacro(RelationIsValid(scan->relation)), \
  88         AssertMacro(PointerIsValid(scan->relation->rd_am)) \
  89 )
  90
  91 #define GET_REL_PROCEDURE(x,y) \
  92 ( \
  93         procedure = relation->rd_am->y, \
  94         (!RegProcedureIsValid(procedure)) ? \
  95                 elog(ERROR, "index_%s: invalid %s regproc", \
  96                         CppAsString(x), CppAsString(y)) \
  97         : (void)NULL \
  98 )
  99
 100 #define GET_SCAN_PROCEDURE(x,y) \
 101 ( \
 102         procedure = scan->relation->rd_am->y, \
 103         (!RegProcedureIsValid(procedure)) ? \
 104                 elog(ERROR, "index_%s: invalid %s regproc", \
 105                         CppAsString(x), CppAsString(y)) \
 106         : (void)NULL \
 107 )
 108
 109
 110 /* ----------------------------------------------------------------
 111  *                                 index_ interface functions
 112  * ----------------------------------------------------------------
 113  */
 114 /* ----------------
 115  *              index_open - open an index relation by relationId
 116  *
 117  *              presently the relcache routines do all the work we need
 118  *              to open/close index relations.  However, callers of index_open
 119  *              expect it to succeed, so we need to check for a failure return.
 120  *
 121  *              Note: we acquire no lock on the index.  An AccessShareLock is
 122  *              acquired by index_beginscan (and released by index_endscan).
 123  * ----------------
 124  */
 125 Relation
 126 index_open(Oid relationId)
 127 {
 128         Relation        r;
 129
 130         r = RelationIdGetRelation(relationId);
 131
 132         if (!RelationIsValid(r))
 133                 elog(ERROR, "Index %u does not exist", relationId);
 134
 135         if (r->rd_rel->relkind != RELKIND_INDEX)
 136                 elog(ERROR, "%s is not an index relation", RelationGetRelationName(r));
 137
 138         return r;
 139 }
 140
 141 /* ----------------
 142  *              index_openr - open a index relation by name
 143  *
 144  *              As above, but lookup by name instead of OID.
 145  * ----------------
 146  */
 147 Relation
 148 index_openr(char *relationName)
 149 {
 150         Relation        r;
 151
 152         r = RelationNameGetRelation(relationName);
 153
 154         if (!RelationIsValid(r))
 155                 elog(ERROR, "Index '%s' does not exist", relationName);
 156
 157         if (r->rd_rel->relkind != RELKIND_INDEX)
 158                 elog(ERROR, "%s is not an index relation", RelationGetRelationName(r));
 159
 160         return r;
 161 }
 162
 163 /* ----------------
 164  *              index_close - close a index relation
 165  *
 166  *              presently the relcache routines do all the work we need
 167  *              to open/close index relations.
 168  * ----------------
 169  */
 170 void
 171 index_close(Relation relation)
 172 {
 173         RelationClose(relation);
 174 }
 175
 176 /* ----------------
 177  *              index_insert - insert an index tuple into a relation
 178  * ----------------
 179  */
 180 InsertIndexResult
 181 index_insert(Relation relation,
 182                          Datum *datum,
 183                          char *nulls,
 184                          ItemPointer heap_t_ctid,
 185                          Relation heapRel)
 186 {
 187         RegProcedure procedure;
 188         InsertIndexResult specificResult;
 189
 190         RELATION_CHECKS;
 191         GET_REL_PROCEDURE(insert, aminsert);
 192
 193         /* ----------------
 194          *      have the am's insert proc do all the work.
 195          * ----------------
 196          */
 197         specificResult = (InsertIndexResult)
 198                 fmgr(procedure, relation, datum, nulls, heap_t_ctid, heapRel, NULL);
 199
 200         /* must be pfree'ed */
 201         return specificResult;
 202 }
 203
 204 /* ----------------
 205  *              index_delete - delete an item from an index relation
 206  * ----------------
 207  */
 208 void
 209 index_delete(Relation relation, ItemPointer indexItem)
 210 {
 211         RegProcedure procedure;
 212
 213         RELATION_CHECKS;
 214         GET_REL_PROCEDURE(delete, amdelete);
 215
 216         fmgr(procedure, relation, indexItem);
 217 }
 218
 219 /* ----------------
 220  *              index_beginscan - start a scan of an index
 221  * ----------------
 222  */
 223 IndexScanDesc
 224 index_beginscan(Relation relation,
 225                                 bool scanFromEnd,
 226                                 uint16 numberOfKeys,
 227                                 ScanKey key)
 228 {
 229         IndexScanDesc scandesc;
 230         RegProcedure procedure;
 231
 232         RELATION_CHECKS;
 233         GET_REL_PROCEDURE(beginscan, ambeginscan);
 234
 235         RelationIncrementReferenceCount(relation);
 236
 237         /* ----------------
 238          *      Acquire AccessShareLock for the duration of the scan
 239          *
 240          *      Note: we could get an SI inval message here and consequently have
 241          *      to rebuild the relcache entry.  The refcount increment above
 242          *      ensures that we will rebuild it and not just flush it...
 243          * ----------------
 244          */
 245         LockRelation(relation, AccessShareLock);
 246
 247         scandesc = (IndexScanDesc)
 248                 fmgr(procedure, relation, scanFromEnd, numberOfKeys, key);
 249
 250         return scandesc;
 251 }
 252
 253 /* ----------------
 254  *              index_rescan  - restart a scan of an index
 255  * ----------------
 256  */
 257 void
 258 index_rescan(IndexScanDesc scan, bool scanFromEnd, ScanKey key)
 259 {
 260         RegProcedure procedure;
 261
 262         SCAN_CHECKS;
 263         GET_SCAN_PROCEDURE(rescan, amrescan);
 264
 265         fmgr(procedure, scan, scanFromEnd, key);
 266 }
 267
 268 /* ----------------
 269  *              index_endscan - end a scan
 270  * ----------------
 271  */
 272 void
 273 index_endscan(IndexScanDesc scan)
 274 {
 275         RegProcedure procedure;
 276
 277         SCAN_CHECKS;
 278         GET_SCAN_PROCEDURE(endscan, amendscan);
 279
 280         fmgr(procedure, scan);
 281
 282         /* Release lock and refcount acquired by index_beginscan */
 283
 284         UnlockRelation(scan->relation, AccessShareLock);
 285
 286         RelationDecrementReferenceCount(scan->relation);
 287
 288         /* Release the scan data structure itself */
 289         IndexScanEnd(scan);
 290 }
 291
 292 /* ----------------
 293  *              index_markpos  - mark a scan position
 294  * ----------------
 295  */
 296 void
 297 index_markpos(IndexScanDesc scan)
 298 {
 299         RegProcedure procedure;
 300
 301         SCAN_CHECKS;
 302         GET_SCAN_PROCEDURE(markpos, ammarkpos);
 303
 304         fmgr(procedure, scan);
 305 }
 306
 307 /* ----------------
 308  *              index_restrpos  - restore a scan position
 309  * ----------------
 310  */
 311 void
 312 index_restrpos(IndexScanDesc scan)
 313 {
 314         RegProcedure procedure;
 315
 316         SCAN_CHECKS;
 317         GET_SCAN_PROCEDURE(restrpos, amrestrpos);
 318
 319         fmgr(procedure, scan);
 320 }
 321
 322 /* ----------------
 323  *              index_getnext - get the next tuple from a scan
 324  *
 325  *              A RetrieveIndexResult is a index tuple/heap tuple pair
 326  * ----------------
 327  */
 328 RetrieveIndexResult
 329 index_getnext(IndexScanDesc scan,
 330                           ScanDirection direction)
 331 {
 332         RetrieveIndexResult result;
 333
 334         SCAN_CHECKS;
 335
 336         /* ----------------
 337          *      Look up the access procedure only once per scan.
 338          * ----------------
 339          */
 340         if (scan->fn_getnext.fn_oid == InvalidOid)
 341         {
 342                 RegProcedure procedure;
 343
 344                 GET_SCAN_PROCEDURE(getnext, amgettuple);
 345                 fmgr_info(procedure, &scan->fn_getnext);
 346         }
 347
 348         /* ----------------
 349          *      have the am's gettuple proc do all the work.
 350          * ----------------
 351          */
 352         result = (RetrieveIndexResult)
 353                 (*fmgr_faddr(&scan->fn_getnext)) (scan, direction);
 354
 355         return result;
 356 }
 357
 358 /* ----------------
 359  *              index_cost_estimator
 360  *
 361  *              Fetch the amcostestimate procedure OID for an index.
 362  *
 363  *              We could combine fetching and calling the procedure,
 364  *              as index_insert does for example; but that would require
 365  *              importing a bunch of planner/optimizer stuff into this file.
 366  * ----------------
 367  */
 368 RegProcedure
 369 index_cost_estimator(Relation relation)
 370 {
 371         RegProcedure procedure;
 372
 373         RELATION_CHECKS;
 374         GET_REL_PROCEDURE(cost_estimator, amcostestimate);
 375
 376         return procedure;
 377 }
 378
 379 /* ----------------
 380  *              index_getprocid
 381  *
 382  *              Some indexed access methods may require support routines that are
 383  *              not in the operator class/operator model imposed by pg_am.      These
 384  *              access methods may store the OIDs of registered procedures they
 385  *              need in pg_amproc.      These registered procedure OIDs are ordered in
 386  *              a way that makes sense to the access method, and used only by the
 387  *              access method.  The general index code doesn't know anything about
 388  *              the routines involved; it just builds an ordered list of them for
 389  *              each attribute on which an index is defined.
 390  *
 391  *              This routine returns the requested procedure OID for a particular
 392  *              indexed attribute.
 393  * ----------------
 394  */
 395 RegProcedure
 396 index_getprocid(Relation irel,
 397                                 AttrNumber attnum,
 398                                 uint16 procnum)
 399 {
 400         RegProcedure *loc;
 401         int                     natts;
 402
 403         natts = irel->rd_rel->relnatts;
 404
 405         loc = irel->rd_support;
 406
 407         Assert(loc != NULL);
 408
 409         return loc[(natts * (procnum - 1)) + (attnum - 1)];
 410 }
 411
 412 Datum
 413 GetIndexValue(HeapTuple tuple,
 414                           TupleDesc hTupDesc,
 415                           int attOff,
 416                           AttrNumber *attrNums,
 417                           FuncIndexInfo *fInfo,
 418                           bool *attNull)
 419 {
 420         Datum           returnVal;
 421
 422         if (PointerIsValid(fInfo) && FIgetProcOid(fInfo) != InvalidOid)
 423         {
 424                 FmgrInfo                                flinfo;
 425                 FunctionCallInfoData    fcinfo;
 426                 int                                             i;
 427                 bool                                    anynull = false;
 428
 429                 /*
 430                  * XXX ought to store lookup info in FuncIndexInfo so it need not
 431                  * be repeated on each call?
 432                  */
 433                 fmgr_info(FIgetProcOid(fInfo), &flinfo);
 434
 435                 MemSet(&fcinfo, 0, sizeof(fcinfo));
 436                 fcinfo.flinfo = &flinfo;
 437                 fcinfo.nargs = FIgetnArgs(fInfo);
 438
 439                 for (i = 0; i < FIgetnArgs(fInfo); i++)
 440                 {
 441                         fcinfo.arg[i] = heap_getattr(tuple,
 442                                                                                  attrNums[i],
 443                                                                                  hTupDesc,
 444                                                                                  &fcinfo.argnull[i]);
 445                         anynull |= fcinfo.argnull[i];
 446                 }
 447                 if (flinfo.fn_strict && anynull)
 448                 {
 449                         /* force a null result for strict function */
 450                         returnVal = (Datum) 0;
 451                         *attNull = true;
 452                 }
 453                 else
 454                 {
 455                         returnVal = FunctionCallInvoke(&fcinfo);
 456                         *attNull = fcinfo.isnull;
 457                 }
 458         }
 459         else
 460                 returnVal = heap_getattr(tuple, attrNums[attOff], hTupDesc, attNull);
 461
 462         return returnVal;
 463 }