ginfuncs.c

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/*
 * ginfuncs.c
 *      Functions to investigate the content of GIN indexes
 *
 * Copyright (c) 2014-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      contrib/pageinspect/ginfuncs.c
 */
#include "postgres.h"
 
#include "access/gin_private.h"
#include "access/htup_details.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pageinspect.h"
#include "utils/array.h"
#include "utils/builtins.h"
 
 
PG_FUNCTION_INFO_V1(gin_metapage_info);
PG_FUNCTION_INFO_V1(gin_page_opaque_info);
PG_FUNCTION_INFO_V1(gin_leafpage_items);
 
 
Datum
gin_metapage_info(PG_FUNCTION_ARGS)
{
    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    TupleDesc   tupdesc;
    Page        page;
    GinPageOpaque opaq;
    GinMetaPageData *metadata;
    HeapTuple   resultTuple;
    Datum       values[10];
    bool        nulls[10];
 
    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to use raw page functions")));
 
    page = get_page_from_raw(raw_page);
 
    if (PageIsNew(page))
        PG_RETURN_NULL();
 
    if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("input page is not a valid GIN metapage"),
                 errdetail("Expected special size %d, got %d.",
                           (int) MAXALIGN(sizeof(GinPageOpaqueData)),
                           (int) PageGetSpecialSize(page))));
 
    opaq = GinPageGetOpaque(page);
 
    if (opaq->flags != GIN_META)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("input page is not a GIN metapage"),
                 errdetail("Flags %04X, expected %04X",
                           opaq->flags, GIN_META)));
 
    /* 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");
 
    metadata = GinPageGetMeta(page);
 
    memset(nulls, 0, sizeof(nulls));
 
    values[0] = Int64GetDatum(metadata->head);
    values[1] = Int64GetDatum(metadata->tail);
    values[2] = Int32GetDatum(metadata->tailFreeSize);
    values[3] = Int64GetDatum(metadata->nPendingPages);
    values[4] = Int64GetDatum(metadata->nPendingHeapTuples);
 
    /* statistics, updated by VACUUM */
    values[5] = Int64GetDatum(metadata->nTotalPages);
    values[6] = Int64GetDatum(metadata->nEntryPages);
    values[7] = Int64GetDatum(metadata->nDataPages);
    values[8] = Int64GetDatum(metadata->nEntries);
 
    values[9] = Int32GetDatum(metadata->ginVersion);
 
    /* Build and return the result tuple. */
    resultTuple = heap_form_tuple(tupdesc, values, nulls);
 
    return HeapTupleGetDatum(resultTuple);
}
 
 
Datum
gin_page_opaque_info(PG_FUNCTION_ARGS)
{
    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    TupleDesc   tupdesc;
    Page        page;
    GinPageOpaque opaq;
    HeapTuple   resultTuple;
    Datum       values[3];
    bool        nulls[3];
    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);
 
    if (PageIsNew(page))
        PG_RETURN_NULL();
 
    if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("input page is not a valid GIN data leaf page"),
                 errdetail("Expected special size %d, got %d.",
                           (int) MAXALIGN(sizeof(GinPageOpaqueData)),
                           (int) PageGetSpecialSize(page))));
 
    opaq = GinPageGetOpaque(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 & GIN_DATA)
        flags[nflags++] = CStringGetTextDatum("data");
    if (flagbits & GIN_LEAF)
        flags[nflags++] = CStringGetTextDatum("leaf");
    if (flagbits & GIN_DELETED)
        flags[nflags++] = CStringGetTextDatum("deleted");
    if (flagbits & GIN_META)
        flags[nflags++] = CStringGetTextDatum("meta");
    if (flagbits & GIN_LIST)
        flags[nflags++] = CStringGetTextDatum("list");
    if (flagbits & GIN_LIST_FULLROW)
        flags[nflags++] = CStringGetTextDatum("list_fullrow");
    if (flagbits & GIN_INCOMPLETE_SPLIT)
        flags[nflags++] = CStringGetTextDatum("incomplete_split");
    if (flagbits & GIN_COMPRESSED)
        flags[nflags++] = CStringGetTextDatum("compressed");
    flagbits &= ~(GIN_DATA | GIN_LEAF | GIN_DELETED | GIN_META | GIN_LIST |
                  GIN_LIST_FULLROW | GIN_INCOMPLETE_SPLIT | GIN_COMPRESSED);
    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] = Int64GetDatum(opaq->rightlink);
    values[1] = Int32GetDatum(opaq->maxoff);
    values[2] = PointerGetDatum(construct_array_builtin(flags, nflags, TEXTOID));
 
    /* Build and return the result tuple. */
    resultTuple = heap_form_tuple(tupdesc, values, nulls);
 
    return HeapTupleGetDatum(resultTuple);
}
 
typedef struct gin_leafpage_items_state
{
    TupleDesc   tupd;
    GinPostingList *seg;
    GinPostingList *lastseg;
} gin_leafpage_items_state;
 
Datum
gin_leafpage_items(PG_FUNCTION_ARGS)
{
    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    FuncCallContext *fctx;
    gin_leafpage_items_state *inter_call_data;
 
    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to use raw page functions")));
 
    if (SRF_IS_FIRSTCALL())
    {
        TupleDesc   tupdesc;
        MemoryContext mctx;
        Page        page;
        GinPageOpaque opaq;
 
        fctx = SRF_FIRSTCALL_INIT();
        mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
 
        page = get_page_from_raw(raw_page);
 
        if (PageIsNew(page))
        {
            MemoryContextSwitchTo(mctx);
            PG_RETURN_NULL();
        }
 
        if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("input page is not a valid GIN data leaf page"),
                     errdetail("Expected special size %d, got %d.",
                               (int) MAXALIGN(sizeof(GinPageOpaqueData)),
                               (int) PageGetSpecialSize(page))));
 
        opaq = GinPageGetOpaque(page);
        if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("input page is not a compressed GIN data leaf page"),
                     errdetail("Flags %04X, expected %04X",
                               opaq->flags,
                               (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
 
        inter_call_data = palloc(sizeof(gin_leafpage_items_state));
 
        /* 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");
 
        inter_call_data->tupd = tupdesc;
 
        inter_call_data->seg = GinDataLeafPageGetPostingList(page);
        inter_call_data->lastseg = (GinPostingList *)
            (((char *) inter_call_data->seg) +
             GinDataLeafPageGetPostingListSize(page));
 
        fctx->user_fctx = inter_call_data;
 
        MemoryContextSwitchTo(mctx);
    }
 
    fctx = SRF_PERCALL_SETUP();
    inter_call_data = fctx->user_fctx;
 
    if (inter_call_data->seg != inter_call_data->lastseg)
    {
        GinPostingList *cur = inter_call_data->seg;
        HeapTuple   resultTuple;
        Datum       result;
        Datum       values[3];
        bool        nulls[3];
        int         ndecoded,
                    i;
        ItemPointer tids;
        Datum      *tids_datum;
 
        memset(nulls, 0, sizeof(nulls));
 
        values[0] = ItemPointerGetDatum(&cur->first);
        values[1] = UInt16GetDatum(cur->nbytes);
 
        /* build an array of decoded item pointers */
        tids = ginPostingListDecode(cur, &ndecoded);
        tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
        for (i = 0; i < ndecoded; i++)
            tids_datum[i] = ItemPointerGetDatum(&tids[i]);
        values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
        pfree(tids_datum);
        pfree(tids);
 
        /* Build and return the result tuple. */
        resultTuple = heap_form_tuple(inter_call_data->tupd, values, nulls);
        result = HeapTupleGetDatum(resultTuple);
 
        inter_call_data->seg = GinNextPostingListSegment(cur);
 
        SRF_RETURN_NEXT(fctx, result);
    }
 
    SRF_RETURN_DONE(fctx);
}