1 /*-------------------------------------------------------------------------
4 * Selectivity routines registered in the operator catalog in the
5 * "oprrest" and "oprjoin" attributes.
7 * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
12 * $PostgreSQL: pgsql/src/backend/utils/adt/geo_selfuncs.c,v 1.23 2004/08/29 04:12:51 momjian Exp $
14 * XXX These are totally bogus. Perhaps someone will make them do
15 * something reasonable, someday.
17 *-------------------------------------------------------------------------
21 #include "utils/geo_decls.h"
25 * Selectivity functions for rtrees. These are bogus -- unless we know
26 * the actual key distribution in the index, we can't make a good prediction
27 * of the selectivity of these operators.
29 * Note: the values used here may look unreasonably small. Perhaps they
30 * are. For now, we want to make sure that the optimizer will make use
31 * of an r-tree index if one is available, so the selectivity had better
34 * In general, rtrees need to search multiple subtrees in order to guarantee
35 * that all occurrences of the same key have been found. Because of this,
36 * the estimated cost for scanning the index ought to be higher than the
37 * output selectivity would indicate. rtcostestimate(), over in selfuncs.c,
38 * ought to be adjusted accordingly --- but until we can generate somewhat
39 * realistic numbers here, it hardly matters...
44 * Selectivity for operators that depend on area, such as "overlap".
48 areasel(PG_FUNCTION_ARGS)
50 PG_RETURN_FLOAT8(0.005);
54 areajoinsel(PG_FUNCTION_ARGS)
56 PG_RETURN_FLOAT8(0.005);
62 * How likely is a box to be strictly left of (right of, above, below)
67 positionsel(PG_FUNCTION_ARGS)
69 PG_RETURN_FLOAT8(0.1);
73 positionjoinsel(PG_FUNCTION_ARGS)
75 PG_RETURN_FLOAT8(0.1);
79 * contsel -- How likely is a box to contain (be contained by) a given box?
81 * This is a tighter constraint than "overlap", so produce a smaller
82 * estimate than areasel does.
86 contsel(PG_FUNCTION_ARGS)
88 PG_RETURN_FLOAT8(0.001);
92 contjoinsel(PG_FUNCTION_ARGS)
94 PG_RETURN_FLOAT8(0.001);