[postgis-devel] Prepared Geometry API

[Paul Ramsey]

I see the datum numbers are also consistently tracking changes when I
add those in:

POSTGIS_DEBUGF(1, "arg 1 pointer(%x) datum(%d)     arg 2 pointer(%x)
datum(%d)", PG_GETARG_POINTER(0), PG_GETARG_DATUM(0),
PG_GETARG_POINTER(1), PG_GETARG_DATUM(1));


Does this mean that using the datum numbers is a possible sol'n?

postgis2=#
                                         postgis2=# SELECT a.val as a,
b.val as b, _st_containsprepared(a.val, b.val,0)postgis2-#
FROMpostgis2-#  (SELECT 'POINT(0 0)'::geometry as val UNION SELECT
'POINT(1 1)'::geometry as val) a,
postgis2-#  (SELECT 'POINT(3 4)'::geometry as val UNION SELECT
'POINT(1 1)'::geometry as val) b;
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3931] arg 1 pointer(731d7c)
datum(7544188)     arg 2 pointer(732e9c) datum(7548572)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3934] arg 1 ewkt: POINT(0 0)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3936] arg 2 ewkt: POINT(1 1)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3931] arg 1 pointer(731d7c)
datum(7544188)     arg 2 pointer(732e54) datum(7548500)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3934] arg 1 ewkt: POINT(0 0)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3936] arg 2 ewkt: POINT(3 4)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3931] arg 1 pointer(73302c)
datum(7548972)     arg 2 pointer(8586f4) datum(8750836)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3934] arg 1 ewkt: POINT(1 1)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3936] arg 2 ewkt: POINT(1 1)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3931] arg 1 pointer(73302c)
datum(7548972)     arg 2 pointer(732f4c) datum(7548748)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3934] arg 1 ewkt: POINT(1 1)
NOTICE:  [lwgeom_geos_c.c:containsPrepared:3936] arg 2 ewkt: POINT(3 4)
                     a                      |                     b
                  | _st_containsprepared
--------------------------------------------+--------------------------------------------+----------------------
 010100000000000000000000000000000000000000 |
0101000000000000000000F03F000000000000F03F | f
 010100000000000000000000000000000000000000 |
010100000000000000000008400000000000001040 | f
 0101000000000000000000F03F000000000000F03F |
0101000000000000000000F03F000000000000F03F | t
 0101000000000000000000F03F000000000000F03F |
010100000000000000000008400000000000001040 | f
(4 rows)



On Tue, Oct 7, 2008 at 1:29 PM, Mark Cave-Ayland
<mark.cave-ayland at siriusit.co.uk> wrote:
> Obe, Regina wrote:
>>
>> Paul,
>>
>> Something is bugging me about your choice of example.  Not that it is
>> important, but your a and b tables are the same constant so I would expect a
>> planner to realize that and make a and b point to the same thing.  I'm not
>> sure how that muddies your analysis. Also your constant gets cast as a
>> geometry only when it gets into ST_Contains and you are doing a UNION
>> instead of a UNION ALL.
>>
>> What does the revised query give you
>>
>> SELECT a.val as a, b.val as b, st_contains(a.val, b.val,0)
>> FROM
>>  (SELECT 'POINT(0 0)'::geometry as val UNION ALL SELECT 'POINT(1
>> 1)'::geometry as val) a,
>>  (SELECT 'POINT(3 4)'::geometry as val UNION ALL SELECT 'POINT(1
>> 1)'::geometry as val) b;
>>
>> Thanks,
>> Regina
>
> The UNION ALL seems to work for me. Using the attached patch against SVN
> trunk and EXPLAIN, it is possible to see that it is the Materialize node
> which causes the Datum pointers to change. Also it's worth noting that
> st_contains() invokes the bounding box filter first which is a little
> confusing when looking at this - things were a lot clearer to me using the
> following queries:
>
>
> SELECT a.val as a, b.val as b, _st_containsprepared(a.val, b.val,0)
> FROM
>  (SELECT 'POINT(0 0)'::geometry as val UNION SELECT 'POINT(1 1)'::geometry
> as val) a,
>  (SELECT 'POINT(3 4)'::geometry as val UNION SELECT 'POINT(1 1)'::geometry
> as val) b;
>
>
> SELECT a.val as a, b.val as b, _st_containsprepared(a.val, b.val,0)
> FROM
>  (SELECT 'POINT(0 0)'::geometry as val UNION ALL SELECT 'POINT(1
> 1)'::geometry as val) a,
>  (SELECT 'POINT(3 4)'::geometry as val UNION ALL SELECT 'POINT(1
> 1)'::geometry as val) b;
>
>
> ATB,
>
> Mark.
>
> --
> Mark Cave-Ayland
> Sirius Corporation - The Open Source Experts
> http://www.siriusit.co.uk
> T: +44 870 608 0063
>
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