brin_2d.c

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#include "postgis_brin.h"

/*
 * As we index geometries but store either a BOX2DF or GIDX according to the
 * operator class, we need to overload the original brin_inclusion_add_value()
 * function to be able to do this. Other original mandatory support functions
 * doesn't need to be overloaded.
 *
 * The previous limitation might be lifted, but we also eliminate some overhead
 * by doing it this way, namely calling different functions through the
 * FunctionCallInvoke machinery for each heap tuple.
 */

PG_FUNCTION_INFO_V1(geom2d_brin_inclusion_add_value);
Datum
geom2d_brin_inclusion_add_value(PG_FUNCTION_ARGS)
{
        BrinValues *column = (BrinValues *) PG_GETARG_POINTER(1);
        Datum      newval = PG_GETARG_DATUM(2);
        bool       isnull = PG_GETARG_BOOL(3);
        BOX2DF     box_geom, *box_key;

        /*
         * If the new value is null, we record that we saw it if it's the first
         * one; otherwise, there's nothing to do.
         */
        if (isnull)
        {
                if (column->bv_hasnulls)
                        PG_RETURN_BOOL(false);

                column->bv_hasnulls = true;
                PG_RETURN_BOOL(true);
        }

        /*
         * check other cases where it is not possible to retrieve a box
         */
        if (gserialized_datum_get_box2df_p(newval, &box_geom) == LW_FAILURE)
        {
                /*
                 * Empty entries have to be supported in the opclass: test the passed
                 * new value for emptiness; if it returns true, we need to set the
                 * "contains empty" flag in the element (unless already set).
                 */
                if (is_gserialized_from_datum_empty(newval)) {
                        if (!DatumGetBool(column->bv_values[INCLUSION_CONTAINS_EMPTY]))
                        {
                                column->bv_values[INCLUSION_CONTAINS_EMPTY] = BoolGetDatum(true);
                                PG_RETURN_BOOL(true);
                        }

                        PG_RETURN_BOOL(false);
                } else
                {
                        /*
                         * in case the entry is not empty and it is not possible to
                         * retrieve a box, raise an error
                         */
                        elog(ERROR, "Error while extracting the box2df from the geom");
                }
        }

        /* if the recorded value is null, we just need to store the box2df */
        if (column->bv_allnulls)
        {
                column->bv_values[INCLUSION_UNION] = datumCopy((Datum) &box_geom, false,
                                sizeof(BOX2DF));
                column->bv_values[INCLUSION_UNMERGEABLE] = BoolGetDatum(false);
                column->bv_values[INCLUSION_CONTAINS_EMPTY] = BoolGetDatum(false);
                column->bv_allnulls = false;
                PG_RETURN_BOOL(true);
        }

        box_key = (BOX2DF *) column->bv_values[INCLUSION_UNION];

        /* Check if the stored bouding box already contains the geometry's one */
        if (box2df_contains(box_key, &box_geom))
                        PG_RETURN_BOOL(false);

        /*
         * Otherwise, we need to enlarge the stored box2df to make it contains the
         * current geometry
         */
        box_key->xmin = Min(box_key->xmin, box_geom.xmin);
        box_key->xmax = Max(box_key->xmax, box_geom.xmax);
        box_key->ymin = Min(box_key->ymin, box_geom.ymin);
        box_key->ymax = Max(box_key->ymax, box_geom.ymax);

        PG_RETURN_BOOL(true);
}