indexing.c

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/*-------------------------------------------------------------------------
 *
 * indexing.c
 *    This file contains routines to support indexes defined on system
 *    catalogs.
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/catalog/indexing.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "executor/executor.h"
#include "utils/rel.h"


/*
 * CatalogOpenIndexes - open the indexes on a system catalog.
 *
 * When inserting or updating tuples in a system catalog, call this
 * to prepare to update the indexes for the catalog.
 *
 * In the current implementation, we share code for opening/closing the
 * indexes with execUtils.c.  But we do not use ExecInsertIndexTuples,
 * because we don't want to create an EState.  This implies that we
 * do not support partial or expressional indexes on system catalogs,
 * nor can we support generalized exclusion constraints.
 * This could be fixed with localized changes here if we wanted to pay
 * the extra overhead of building an EState.
 */
CatalogIndexState
CatalogOpenIndexes(Relation heapRel)
{
    ResultRelInfo *resultRelInfo;

    resultRelInfo = makeNode(ResultRelInfo);
    resultRelInfo->ri_RangeTableIndex = 1;      /* dummy */
    resultRelInfo->ri_RelationDesc = heapRel;
    resultRelInfo->ri_TrigDesc = NULL;  /* we don't fire triggers */

    ExecOpenIndices(resultRelInfo);

    return resultRelInfo;
}

/*
 * CatalogCloseIndexes - clean up resources allocated by CatalogOpenIndexes
 */
void
CatalogCloseIndexes(CatalogIndexState indstate)
{
    ExecCloseIndices(indstate);
    pfree(indstate);
}

/*
 * CatalogIndexInsert - insert index entries for one catalog tuple
 *
 * This should be called for each inserted or updated catalog tuple.
 *
 * This is effectively a cut-down version of ExecInsertIndexTuples.
 */
void
CatalogIndexInsert(CatalogIndexState indstate, HeapTuple heapTuple)
{
    int         i;
    int         numIndexes;
    RelationPtr relationDescs;
    Relation    heapRelation;
    TupleTableSlot *slot;
    IndexInfo **indexInfoArray;
    Datum       values[INDEX_MAX_KEYS];
    bool        isnull[INDEX_MAX_KEYS];

    /* HOT update does not require index inserts */
    if (HeapTupleIsHeapOnly(heapTuple))
        return;

    /*
     * Get information from the state structure.  Fall out if nothing to do.
     */
    numIndexes = indstate->ri_NumIndices;
    if (numIndexes == 0)
        return;
    relationDescs = indstate->ri_IndexRelationDescs;
    indexInfoArray = indstate->ri_IndexRelationInfo;
    heapRelation = indstate->ri_RelationDesc;

    /* Need a slot to hold the tuple being examined */
    slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation));
    ExecStoreTuple(heapTuple, slot, InvalidBuffer, false);

    /*
     * for each index, form and insert the index tuple
     */
    for (i = 0; i < numIndexes; i++)
    {
        IndexInfo  *indexInfo;

        indexInfo = indexInfoArray[i];

        /* If the index is marked as read-only, ignore it */
        if (!indexInfo->ii_ReadyForInserts)
            continue;

        /*
         * Expressional and partial indexes on system catalogs are not
         * supported, nor exclusion constraints, nor deferred uniqueness
         */
        Assert(indexInfo->ii_Expressions == NIL);
        Assert(indexInfo->ii_Predicate == NIL);
        Assert(indexInfo->ii_ExclusionOps == NULL);
        Assert(relationDescs[i]->rd_index->indimmediate);

        /*
         * FormIndexDatum fills in its values and isnull parameters with the
         * appropriate values for the column(s) of the index.
         */
        FormIndexDatum(indexInfo,
                       slot,
                       NULL,    /* no expression eval to do */
                       values,
                       isnull);

        /*
         * The index AM does the rest.
         */
        index_insert(relationDescs[i],  /* index relation */
                     values,    /* array of index Datums */
                     isnull,    /* is-null flags */
                     &(heapTuple->t_self),      /* tid of heap tuple */
                     heapRelation,
                     relationDescs[i]->rd_index->indisunique ?
                     UNIQUE_CHECK_YES : UNIQUE_CHECK_NO);
    }

    ExecDropSingleTupleTableSlot(slot);
}

/*
 * CatalogUpdateIndexes - do all the indexing work for a new catalog tuple
 *
 * This is a convenience routine for the common case where we only need
 * to insert or update a single tuple in a system catalog.  Avoid using it for
 * multiple tuples, since opening the indexes and building the index info
 * structures is moderately expensive.
 */
void
CatalogUpdateIndexes(Relation heapRel, HeapTuple heapTuple)
{
    CatalogIndexState indstate;

    indstate = CatalogOpenIndexes(heapRel);
    CatalogIndexInsert(indstate, heapTuple);
    CatalogCloseIndexes(indstate);
}