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/*-------------------------------------------------------------------------
*
* geo_selfuncs.c
* Selectivity routines registered in the operator catalog in the
* "oprrest" and "oprjoin" attributes.
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/utils/adt/geo_selfuncs.c
*
* XXX These are totally bogus. Perhaps someone will make them do
* something reasonable, someday.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "utils/builtins.h"
#include "utils/geo_decls.h"
/*
* Selectivity functions for geometric operators. These are bogus -- unless
* we know the actual key distribution in the index, we can't make a good
* prediction of the selectivity of these operators.
*
* Note: the values used here may look unreasonably small. Perhaps they
* are. For now, we want to make sure that the optimizer will make use
* of a geometric index if one is available, so the selectivity had better
* be fairly small.
*
* In general, GiST needs to search multiple subtrees in order to guarantee
* that all occurrences of the same key have been found. Because of this,
* the estimated cost for scanning the index ought to be higher than the
* output selectivity would indicate. gistcostestimate(), over in selfuncs.c,
* ought to be adjusted accordingly --- but until we can generate somewhat
* realistic numbers here, it hardly matters...
*/
/*
* Selectivity for operators that depend on area, such as "overlap".
*/
Datum
areasel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(0.005);
}
Datum
areajoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(0.005);
}
/*
* positionsel
*
* How likely is a box to be strictly left of (right of, above, below)
* a given box?
*/
Datum
positionsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(0.1);
}
Datum
positionjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(0.1);
}
/*
* contsel -- How likely is a box to contain (be contained by) a given box?
*
* This is a tighter constraint than "overlap", so produce a smaller
* estimate than areasel does.
*/
Datum
contsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(0.001);
}
Datum
contjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(0.001);
}
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