gistfuncs.c

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/*
 * gistfuncs.c
 *      Functions to investigate the content of GiST indexes
 *
 * Copyright (c) 2014-2021, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      contrib/pageinspect/gistfuncs.c
 */
#include "postgres.h"

#include "access/gist.h"
#include "access/gist_private.h"
#include "access/htup.h"
#include "access/relation.h"
#include "catalog/namespace.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pageinspect.h"
#include "storage/itemptr.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/pg_lsn.h"
#include "utils/varlena.h"

PG_FUNCTION_INFO_V1(gist_page_opaque_info);
PG_FUNCTION_INFO_V1(gist_page_items);
PG_FUNCTION_INFO_V1(gist_page_items_bytea);

#define ItemPointerGetDatum(X)   PointerGetDatum(X)


Datum
gist_page_opaque_info(PG_FUNCTION_ARGS)
{
    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    TupleDesc   tupdesc;
    Page        page;
    GISTPageOpaque opaq;
    HeapTuple   resultTuple;
    Datum       values[4];
    bool        nulls[4];
    Datum       flags[16];
    int         nflags = 0;
    uint16      flagbits;

    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to use raw page functions")));

    page = get_page_from_raw(raw_page);

    opaq = (GISTPageOpaque) PageGetSpecialPointer(page);

    /* Build a tuple descriptor for our result type */
    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    /* Convert the flags bitmask to an array of human-readable names */
    flagbits = opaq->flags;
    if (flagbits & F_LEAF)
        flags[nflags++] = CStringGetTextDatum("leaf");
    if (flagbits & F_DELETED)
        flags[nflags++] = CStringGetTextDatum("deleted");
    if (flagbits & F_TUPLES_DELETED)
        flags[nflags++] = CStringGetTextDatum("tuples_deleted");
    if (flagbits & F_FOLLOW_RIGHT)
        flags[nflags++] = CStringGetTextDatum("follow_right");
    if (flagbits & F_HAS_GARBAGE)
        flags[nflags++] = CStringGetTextDatum("has_garbage");
    flagbits &= ~(F_LEAF | F_DELETED | F_TUPLES_DELETED | F_FOLLOW_RIGHT | F_HAS_GARBAGE);
    if (flagbits)
    {
        /* any flags we don't recognize are printed in hex */
        flags[nflags++] = DirectFunctionCall1(to_hex32, Int32GetDatum(flagbits));
    }

    memset(nulls, 0, sizeof(nulls));

    values[0] = LSNGetDatum(PageGetLSN(page));
    values[1] = LSNGetDatum(GistPageGetNSN(page));
    values[2] = Int64GetDatum(opaq->rightlink);
    values[3] = PointerGetDatum(construct_array(flags, nflags,
                                                TEXTOID,
                                                -1, false, TYPALIGN_INT));

    /* Build and return the result tuple. */
    resultTuple = heap_form_tuple(tupdesc, values, nulls);

    return HeapTupleGetDatum(resultTuple);
}

Datum
gist_page_items_bytea(PG_FUNCTION_ARGS)
{
    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    bool        randomAccess;
    TupleDesc   tupdesc;
    Tuplestorestate *tupstore;
    MemoryContext oldcontext;
    Page        page;
    OffsetNumber offset;
    OffsetNumber maxoff = InvalidOffsetNumber;

    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to use raw page functions")));

    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize))
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("materialize mode required, but it is not allowed in this context")));

    /* The tupdesc and tuplestore must be created in ecxt_per_query_memory */
    oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);

    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    randomAccess = (rsinfo->allowedModes & SFRM_Materialize_Random) != 0;
    tupstore = tuplestore_begin_heap(randomAccess, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = tupdesc;

    MemoryContextSwitchTo(oldcontext);

    page = get_page_from_raw(raw_page);

    /* Avoid bogus PageGetMaxOffsetNumber() call with deleted pages */
    if (GistPageIsDeleted(page))
        elog(NOTICE, "page is deleted");
    else
        maxoff = PageGetMaxOffsetNumber(page);

    for (offset = FirstOffsetNumber;
         offset <= maxoff;
         offset++)
    {
        Datum       values[5];
        bool        nulls[5];
        ItemId      id;
        IndexTuple  itup;
        bytea      *tuple_bytea;
        int         tuple_len;

        id = PageGetItemId(page, offset);

        if (!ItemIdIsValid(id))
            elog(ERROR, "invalid ItemId");

        itup = (IndexTuple) PageGetItem(page, id);
        tuple_len = IndexTupleSize(itup);

        memset(nulls, 0, sizeof(nulls));

        values[0] = DatumGetInt16(offset);
        values[1] = ItemPointerGetDatum(&itup->t_tid);
        values[2] = Int32GetDatum((int) IndexTupleSize(itup));

        tuple_bytea = (bytea *) palloc(tuple_len + VARHDRSZ);
        SET_VARSIZE(tuple_bytea, tuple_len + VARHDRSZ);
        memcpy(VARDATA(tuple_bytea), itup, tuple_len);
        values[3] = BoolGetDatum(ItemIdIsDead(id));
        values[4] = PointerGetDatum(tuple_bytea);

        tuplestore_putvalues(tupstore, tupdesc, values, nulls);
    }

    return (Datum) 0;
}

Datum
gist_page_items(PG_FUNCTION_ARGS)
{
    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    Oid         indexRelid = PG_GETARG_OID(1);
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    bool        randomAccess;
    Relation    indexRel;
    TupleDesc   tupdesc;
    Tuplestorestate *tupstore;
    MemoryContext oldcontext;
    Page        page;
    OffsetNumber offset;
    OffsetNumber maxoff = InvalidOffsetNumber;

    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to use raw page functions")));

    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize))
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("materialize mode required, but it is not allowed in this context")));

    /* The tupdesc and tuplestore must be created in ecxt_per_query_memory */
    oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);

    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    randomAccess = (rsinfo->allowedModes & SFRM_Materialize_Random) != 0;
    tupstore = tuplestore_begin_heap(randomAccess, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = tupdesc;

    MemoryContextSwitchTo(oldcontext);

    /* Open the relation */
    indexRel = index_open(indexRelid, AccessShareLock);

    page = get_page_from_raw(raw_page);

    /* Avoid bogus PageGetMaxOffsetNumber() call with deleted pages */
    if (GistPageIsDeleted(page))
        elog(NOTICE, "page is deleted");
    else
        maxoff = PageGetMaxOffsetNumber(page);

    for (offset = FirstOffsetNumber;
         offset <= maxoff;
         offset++)
    {
        Datum       values[5];
        bool        nulls[5];
        ItemId      id;
        IndexTuple  itup;
        Datum       itup_values[INDEX_MAX_KEYS];
        bool        itup_isnull[INDEX_MAX_KEYS];
        char       *key_desc;

        id = PageGetItemId(page, offset);

        if (!ItemIdIsValid(id))
            elog(ERROR, "invalid ItemId");

        itup = (IndexTuple) PageGetItem(page, id);

        index_deform_tuple(itup, RelationGetDescr(indexRel),
                           itup_values, itup_isnull);

        memset(nulls, 0, sizeof(nulls));

        values[0] = DatumGetInt16(offset);
        values[1] = ItemPointerGetDatum(&itup->t_tid);
        values[2] = Int32GetDatum((int) IndexTupleSize(itup));
        values[3] = BoolGetDatum(ItemIdIsDead(id));

        key_desc = BuildIndexValueDescription(indexRel, itup_values, itup_isnull);
        if (key_desc)
            values[4] = CStringGetTextDatum(key_desc);
        else
        {
            values[4] = (Datum) 0;
            nulls[4] = true;
        }

        tuplestore_putvalues(tupstore, tupdesc, values, nulls);
    }

    relation_close(indexRel, AccessShareLock);

    return (Datum) 0;
}