gserialized_estimated_extent()

Datum gserialized_estimated_extent

(

PG_FUNCTION_ARGS

)

Definition at line 2441 of file gserialized_estimate.c.

{
        text *coltxt = NULL;
        char *col = NULL;
        int16 attnum, idx_attnum;
        Oid atttypid = InvalidOid;
        char nsp_tbl[2*NAMEDATALEN+6];
        char *tbl = NULL;
        Oid tbl_oid, idx_oid = 0;
        ND_STATS *nd_stats;
        GBOX *gbox = NULL;
        bool only_parent = false;
        int key_type;
        Oid geographyOid = postgis_oid(GEOGRAPHYOID);
        Oid geometryOid = postgis_oid(GEOMETRYOID);
 
        /* We need to initialize the internal cache to access it later via postgis_oid() */
        postgis_initialize_cache();
 
        if (PG_NARGS() < 2 || PG_NARGS() > 4)
                elog(ERROR, "ST_EstimatedExtent() called with wrong number of arguments");
 
        if ( PG_NARGS() == 4 )
        {
                only_parent = PG_GETARG_BOOL(3);
        }
        if ( PG_NARGS() >= 3 )
        {
                char *nsp = text_to_cstring(PG_GETARG_TEXT_P(0));
                tbl = text_to_cstring(PG_GETARG_TEXT_P(1));
                coltxt = PG_GETARG_TEXT_P(2);
                snprintf(nsp_tbl, sizeof(nsp_tbl), "\"%s\".\"%s\"", nsp, tbl);
        }
        if ( PG_NARGS() == 2 )
        {
                tbl = text_to_cstring(PG_GETARG_TEXT_P(0));
                coltxt = PG_GETARG_TEXT_P(1);
                snprintf(nsp_tbl, sizeof(nsp_tbl), "\"%s\"", tbl);
        }
 
        /* Parse the namespace/table strings and lookup in system catalogs */
        tbl_oid = DatumGetObjectId(DirectFunctionCall1(regclassin, CStringGetDatum(nsp_tbl)));
        if (!tbl_oid)
                elog(ERROR, "cannot lookup table %s", nsp_tbl);
 
    /* Get the attribute number and type from the column name */
    col = text_to_cstring(coltxt);
    if (!get_attnum_attypid(tbl_oid, col, &attnum, &atttypid))
        elog(ERROR, "column %s.\"%s\" does not exist", nsp_tbl, col);
 
    /* We can only do estimates on geograpy and geometry */
    if ((atttypid != geographyOid) && (atttypid != geometryOid))
    {
        elog(ERROR, "column %s.\"%s\" must be a geometry or geography", nsp_tbl, col);
    }
 
        /* Read the extent from the head of the spatial index */
        /* works if there is a spatial index */
        idx_oid = table_get_spatial_index(tbl_oid, attnum, &key_type, &idx_attnum);
        if (idx_oid != InvalidOid)
        {
                /* TODO: how about only_parent ? */
                gbox = spatial_index_read_extent(idx_oid, idx_attnum, key_type);
                elog(DEBUG3, "index for %s.\"%s\" exists, reading gbox from there", nsp_tbl, col);
                if (!gbox) PG_RETURN_NULL();
        }
        /* Read the extent from the stats tables, */
        /* works if ANALYZE has been run */
        else
        {
                int stats_mode = 2;
                elog(DEBUG3, "index for %s.\"%s\" does not exist", nsp_tbl, col);
 
                /* For a geography column, we need the XYZ geocentric bounds */
                if (atttypid == geographyOid)
                        stats_mode = 3;
 
                /* ND stats include an extent for the histogram */
                nd_stats = pg_get_nd_stats_by_name(tbl_oid, coltxt, stats_mode, only_parent);
 
                /* Error out on no stats */
                if (!nd_stats)
                {
                        elog(WARNING, "stats for \"%s.%s\" do not exist", tbl, col);
                        PG_RETURN_NULL();
                }
 
                /* Construct the box */
                gbox = gbox_new(0);
                gbox->xmin = nd_stats->extent.min[0];
                gbox->xmax = nd_stats->extent.max[0];
                gbox->ymin = nd_stats->extent.min[1];
                gbox->ymax = nd_stats->extent.max[1];
                if (stats_mode != 2)
                {
                        FLAGS_SET_Z(gbox->flags, 1);
                        gbox->zmin = nd_stats->extent.min[2];
                        gbox->zmax = nd_stats->extent.max[2];
                }
 
                pfree(nd_stats);
        }
 
        /* Convert geocentric geography box into a planar box */
        /* that users understand */
        if (atttypid == geographyOid)
        {
                GBOX *gbox_planar = gbox_new(0);
                gbox_geocentric_get_gbox_cartesian(gbox, gbox_planar);
                PG_RETURN_POINTER(gbox_planar);
        }
        else
                PG_RETURN_POINTER(gbox);
}

References ND_STATS_T::extent, GBOX::flags, FLAGS_SET_Z, gbox_geocentric_get_gbox_cartesian(), gbox_new(), get_attnum_attypid(), ND_BOX_T::max, ND_BOX_T::min, pg_get_nd_stats_by_name(), spatial_index_read_extent(), table_get_spatial_index(), GBOX::xmax, GBOX::xmin, GBOX::ymax, GBOX::ymin, GBOX::zmax, and GBOX::zmin.

Referenced by geometry_estimated_extent().

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