gserialized_gist_geog_distance()

Datum gserialized_gist_geog_distance

(

PG_FUNCTION_ARGS

)

Definition at line 1268 of file gserialized_gist_nd.c.

{
        GISTENTRY *entry = (GISTENTRY *)PG_GETARG_POINTER(0);
        Datum query_datum = PG_GETARG_DATUM(1);
        StrategyNumber strategy = (StrategyNumber)PG_GETARG_UINT16(2);
        bool *recheck = (bool *)PG_GETARG_POINTER(4);
        char query_box_mem[GIDX_MAX_SIZE];
        GIDX *query_box = (GIDX *)query_box_mem;
        GIDX *entry_box;
        double distance;
 
        POSTGIS_DEBUGF(3, "[GIST] '%s' function called", __func__);
 
        /* We are using '13' as the gist geography distance <-> strategy number */
        if (strategy != 13)
        {
                elog(ERROR, "unrecognized strategy number: %d", strategy);
                PG_RETURN_FLOAT8(FLT_MAX);
        }
 
        /* Null box should never make this far. */
        if (gserialized_datum_get_gidx_p(query_datum, query_box) == LW_FAILURE)
        {
                POSTGIS_DEBUG(2, "[GIST] null query_gbox_index!");
                PG_RETURN_FLOAT8(FLT_MAX);
        }
 
        /* When we hit leaf nodes, it's time to turn on recheck */
        if (GIST_LEAF(entry))
                *recheck = true;
 
        /* Get the entry box */
        entry_box = (GIDX *)PG_DETOAST_DATUM(entry->key);
 
        /* Return distances from key-based tests should always be */
        /* the minimum possible distance, box-to-box */
        /* We scale up to "world units" so that the box-to-box distances */
        /* compare reasonably with the over-the-spheroid distances that */
        /* the recheck process will turn up */
        distance = WGS84_RADIUS * gidx_distance(entry_box, query_box, 0);
        POSTGIS_DEBUGF(2, "[GIST] '%s' got distance %g", __func__, distance);
 
        PG_RETURN_FLOAT8(distance);
}

References distance(), gidx_distance(), LW_FAILURE, and WGS84_RADIUS.

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