/*------------------------------------------------------------------------- * * indexam.c * general index access method routines * * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.47 2001/01/24 19:42:48 momjian Exp $ * * INTERFACE ROUTINES * index_open - open an index relation by relationId * index_openr - open a index relation by name * index_close - close a index relation * index_beginscan - start a scan of an index * index_rescan - restart a scan of an index * index_endscan - end a scan * index_insert - insert an index tuple into a relation * index_delete - delete an item from an index relation * index_markpos - mark a scan position * index_restrpos - restore a scan position * index_getnext - get the next tuple from a scan * ** index_fetch - retrieve tuple with tid * ** index_replace - replace a tuple * ** index_getattr - get an attribute from an index tuple * index_getprocid - get a support procedure id from the rel tuple * * IndexScanIsValid - check index scan * * NOTES * This file contains the index_ routines which used * to be a scattered collection of stuff in access/genam. * * The ** routines: index_fetch, index_replace, and index_getattr * have not yet been implemented. They may not be needed. * * old comments * Scans are implemented as follows: * * `0' represents an invalid item pointer. * `-' represents an unknown item pointer. * `X' represents a known item pointers. * `+' represents known or invalid item pointers. * `*' represents any item pointers. * * State is represented by a triple of these symbols in the order of * previous, current, next. Note that the case of reverse scans works * identically. * * State Result * (1) + + - + 0 0 (if the next item pointer is invalid) * (2) + X - (otherwise) * (3) * 0 0 * 0 0 (no change) * (4) + X 0 X 0 0 (shift) * (5) * + X + X - (shift, add unknown) * * All other states cannot occur. * * Note: It would be possible to cache the status of the previous and * next item pointer using the flags. * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/genam.h" #include "access/heapam.h" #include "utils/relcache.h" /* ---------------------------------------------------------------- * macros used in index_ routines * ---------------------------------------------------------------- */ #define RELATION_CHECKS \ ( \ AssertMacro(RelationIsValid(relation)), \ AssertMacro(PointerIsValid(relation->rd_am)) \ ) #define SCAN_CHECKS \ ( \ AssertMacro(IndexScanIsValid(scan)), \ AssertMacro(RelationIsValid(scan->relation)), \ AssertMacro(PointerIsValid(scan->relation->rd_am)) \ ) #define GET_REL_PROCEDURE(x,y) \ ( \ procedure = relation->rd_am->y, \ (!RegProcedureIsValid(procedure)) ? \ elog(ERROR, "index_%s: invalid %s regproc", \ CppAsString(x), CppAsString(y)) \ : (void)NULL \ ) #define GET_SCAN_PROCEDURE(x,y) \ ( \ procedure = scan->relation->rd_am->y, \ (!RegProcedureIsValid(procedure)) ? \ elog(ERROR, "index_%s: invalid %s regproc", \ CppAsString(x), CppAsString(y)) \ : (void)NULL \ ) /* ---------------------------------------------------------------- * index_ interface functions * ---------------------------------------------------------------- */ /* ---------------- * index_open - open an index relation by relationId * * presently the relcache routines do all the work we need * to open/close index relations. However, callers of index_open * expect it to succeed, so we need to check for a failure return. * * Note: we acquire no lock on the index. An AccessShareLock is * acquired by index_beginscan (and released by index_endscan). * ---------------- */ Relation index_open(Oid relationId) { Relation r; r = RelationIdGetRelation(relationId); if (!RelationIsValid(r)) elog(ERROR, "Index %u does not exist", relationId); if (r->rd_rel->relkind != RELKIND_INDEX) elog(ERROR, "%s is not an index relation", RelationGetRelationName(r)); return r; } /* ---------------- * index_openr - open a index relation by name * * As above, but lookup by name instead of OID. * ---------------- */ Relation index_openr(char *relationName) { Relation r; r = RelationNameGetRelation(relationName); if (!RelationIsValid(r)) elog(ERROR, "Index '%s' does not exist", relationName); if (r->rd_rel->relkind != RELKIND_INDEX) elog(ERROR, "%s is not an index relation", RelationGetRelationName(r)); return r; } /* ---------------- * index_close - close a index relation * * presently the relcache routines do all the work we need * to open/close index relations. * ---------------- */ void index_close(Relation relation) { RelationClose(relation); } /* ---------------- * index_insert - insert an index tuple into a relation * ---------------- */ InsertIndexResult index_insert(Relation relation, Datum *datum, char *nulls, ItemPointer heap_t_ctid, Relation heapRel) { RegProcedure procedure; InsertIndexResult specificResult; RELATION_CHECKS; GET_REL_PROCEDURE(insert, aminsert); /* ---------------- * have the am's insert proc do all the work. * ---------------- */ specificResult = (InsertIndexResult) DatumGetPointer(OidFunctionCall5(procedure, PointerGetDatum(relation), PointerGetDatum(datum), PointerGetDatum(nulls), PointerGetDatum(heap_t_ctid), PointerGetDatum(heapRel))); /* must be pfree'ed */ return specificResult; } /* ---------------- * index_delete - delete an item from an index relation * ---------------- */ void index_delete(Relation relation, ItemPointer indexItem) { RegProcedure procedure; RELATION_CHECKS; GET_REL_PROCEDURE(delete, amdelete); OidFunctionCall2(procedure, PointerGetDatum(relation), PointerGetDatum(indexItem)); } /* ---------------- * index_beginscan - start a scan of an index * ---------------- */ IndexScanDesc index_beginscan(Relation relation, bool scanFromEnd, uint16 numberOfKeys, ScanKey key) { IndexScanDesc scandesc; RegProcedure procedure; RELATION_CHECKS; GET_REL_PROCEDURE(beginscan, ambeginscan); RelationIncrementReferenceCount(relation); /* ---------------- * Acquire AccessShareLock for the duration of the scan * * Note: we could get an SI inval message here and consequently have * to rebuild the relcache entry. The refcount increment above * ensures that we will rebuild it and not just flush it... * ---------------- */ LockRelation(relation, AccessShareLock); scandesc = (IndexScanDesc) DatumGetPointer(OidFunctionCall4(procedure, PointerGetDatum(relation), BoolGetDatum(scanFromEnd), UInt16GetDatum(numberOfKeys), PointerGetDatum(key))); return scandesc; } /* ---------------- * index_rescan - restart a scan of an index * ---------------- */ void index_rescan(IndexScanDesc scan, bool scanFromEnd, ScanKey key) { RegProcedure procedure; SCAN_CHECKS; GET_SCAN_PROCEDURE(rescan, amrescan); OidFunctionCall3(procedure, PointerGetDatum(scan), BoolGetDatum(scanFromEnd), PointerGetDatum(key)); } /* ---------------- * index_endscan - end a scan * ---------------- */ void index_endscan(IndexScanDesc scan) { RegProcedure procedure; SCAN_CHECKS; GET_SCAN_PROCEDURE(endscan, amendscan); OidFunctionCall1(procedure, PointerGetDatum(scan)); /* Release lock and refcount acquired by index_beginscan */ UnlockRelation(scan->relation, AccessShareLock); RelationDecrementReferenceCount(scan->relation); /* Release the scan data structure itself */ IndexScanEnd(scan); } /* ---------------- * index_markpos - mark a scan position * ---------------- */ void index_markpos(IndexScanDesc scan) { RegProcedure procedure; SCAN_CHECKS; GET_SCAN_PROCEDURE(markpos, ammarkpos); OidFunctionCall1(procedure, PointerGetDatum(scan)); } /* ---------------- * index_restrpos - restore a scan position * ---------------- */ void index_restrpos(IndexScanDesc scan) { RegProcedure procedure; SCAN_CHECKS; GET_SCAN_PROCEDURE(restrpos, amrestrpos); OidFunctionCall1(procedure, PointerGetDatum(scan)); } /* ---------------- * index_getnext - get the next tuple from a scan * * A RetrieveIndexResult is a index tuple/heap tuple pair * ---------------- */ RetrieveIndexResult index_getnext(IndexScanDesc scan, ScanDirection direction) { RetrieveIndexResult result; SCAN_CHECKS; /* ---------------- * Look up the access procedure only once per scan. * ---------------- */ if (scan->fn_getnext.fn_oid == InvalidOid) { RegProcedure procedure; GET_SCAN_PROCEDURE(getnext, amgettuple); fmgr_info(procedure, &scan->fn_getnext); } /* ---------------- * have the am's gettuple proc do all the work. * ---------------- */ result = (RetrieveIndexResult) DatumGetPointer(FunctionCall2(&scan->fn_getnext, PointerGetDatum(scan), Int32GetDatum(direction))); return result; } /* ---------------- * index_cost_estimator * * Fetch the amcostestimate procedure OID for an index. * * We could combine fetching and calling the procedure, * as index_insert does for example; but that would require * importing a bunch of planner/optimizer stuff into this file. * ---------------- */ RegProcedure index_cost_estimator(Relation relation) { RegProcedure procedure; RELATION_CHECKS; GET_REL_PROCEDURE(cost_estimator, amcostestimate); return procedure; } /* ---------------- * index_getprocid * * Some indexed access methods may require support routines that are * not in the operator class/operator model imposed by pg_am. These * access methods may store the OIDs of registered procedures they * need in pg_amproc. These registered procedure OIDs are ordered in * a way that makes sense to the access method, and used only by the * access method. The general index code doesn't know anything about * the routines involved; it just builds an ordered list of them for * each attribute on which an index is defined. * * This routine returns the requested procedure OID for a particular * indexed attribute. * ---------------- */ RegProcedure index_getprocid(Relation irel, AttrNumber attnum, uint16 procnum) { RegProcedure *loc; int natts; natts = irel->rd_rel->relnatts; loc = irel->rd_support; Assert(loc != NULL); return loc[(natts * (procnum - 1)) + (attnum - 1)]; }