"...and you get an extra WKT->WKB conversion because the select produces a textual representation of the column. ..." You mean "WKB->WKT conversion", don't you? Why is this last conversion needed? Isn't it extra work for monetdb? Is there any way to tweak the code in order to bypass the last conversion ? On Wed, Apr 27, 2011 at 4:36 PM, Sjoerd Mullender <sjoerd@acm.org> wrote:
On 2011-04-27 14:52, Kostis Kyzirakos wrote:
In Postgres the WKB representation of a geometry is returned as a byte array. For example,
LGD=# SELECT ST_AsBinary(ST_GeomFromText('POINT(1 2)',-1)); st_asbinary ---------------------------------------------- \x0101000000000000000000f03f0000000000000040 (1 row)
This is not available in MonetDB (as far as I can tell by quickly looking at the code).
What you get when you do SELECT * FROM t; where t contains a column of type geometry is the string representation of the internal (WKB) representation produced by the function GEOSGeomToWKT(). I.e., one conversion WKB->WKT.
If you do SELECT GeomFromText(g,0) FROM t; where g is a column of type geometry, it does a conversion WKB->WKT->WKB->WKT because an intermediate table is created with the result of GeomFromText. GeomFromText expects a string (varchar) and so an automatic WKB->WKT conversion takes place. GeomFromText itself does the WKT->WKB conversion, and you get an extra WKT->WKB conversion because the select produces a textual representation of the column.
On Wed, Apr 27, 2011 at 3:46 PM, Sjoerd Mullender <sjoerd@acm.org <mailto:sjoerd@acm.org>> wrote:
On 2011-04-27 14:37, Georgios Garmpis wrote: > I have tried GeomFromText but it doesn't seem to return WKB. > > sql>SELECT GeomFromText('POINT(1 2)', 0); >
+----------------------------------------------------------------------------+
> | geomfromtext_single_value | > +======================================+ > | POINT (1.0000000000000000 2.0000000000000000) | >
+----------------------------------------------------------------------------+
> 1 tuple (0.325ms)
Then what do you expect (or wish to get)? What would the WKB look
like
at the SQL level?
> > > On Wed, Apr 27, 2011 at 3:30 PM, Sjoerd Mullender <sjoerd@acm.org <mailto:sjoerd@acm.org> > <mailto:sjoerd@acm.org <mailto:sjoerd@acm.org>>> wrote: > > On 2011-04-27 11:30, Georgios Garmpis wrote: > > In SQL > > > > I need something like that SELECT AsWKB('POINT(1, 2)'); > > What about this: > SELECT GeomFromText('POINT(1 2)', 0); > > The string ('POINT(1 2)') should not have a comma in it, and the extra > argument (0) is ignored. > > > On Wed, Apr 27, 2011 at 12:09 PM, <Stefan.Manegold@cwi.nl <mailto:Stefan.Manegold@cwi.nl> > <mailto:Stefan.Manegold@cwi.nl <mailto:Stefan.Manegold@cwi.nl
> > <mailto:Stefan.Manegold@cwi.nl <mailto:Stefan.Manegold@cwi.nl> <mailto:Stefan.Manegold@cwi.nl <mailto:Stefan.Manegold@cwi.nl>>>> > wrote: > > > > George, > > > > where do you need to get the Well Known Binary representation of a > > geometry? > > As documentation? > > In C? > > In MAL? > > In SQL? > > > > Stefan > > > > On Wed, Apr 27, 2011 at 11:50:53AM +0300, Georgios Garmpis wrote: > > > Hi, > > > > > > I need to get the Well Known Binary representation of a > geometry but > > > I didn't find any function in documentation to do this. > > > Any ideas? > > > > > > -- > > > George Garbis > > > > > > > >
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> > http://p.sf.net/sfu/whatsupgold-sd > > _______________________________________________ > > MonetDB-users mailing list > > MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net> > <mailto:MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net>> > > <mailto:MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net> > <mailto:MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net>>> > >
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> > > > > > > > > > -- > > George Garbis > > > > > > > > >
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> > WhatsUp Gold - Download Free Network Management Software > > The most intuitive, comprehensive, and cost-effective network > > management toolset available today. Delivers lowest initial > > acquisition cost and overall TCO of any competing solution. > > http://p.sf.net/sfu/whatsupgold-sd > > > > > > > > _______________________________________________ > > MonetDB-users mailing list > > MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net> > <mailto:MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net>> > > https://lists.sourceforge.net/lists/listinfo/monetdb-users > > > -- > Sjoerd Mullender > > >
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> WhatsUp Gold - Download Free Network Management Software > The most intuitive, comprehensive, and cost-effective network > management toolset available today. Delivers lowest initial > acquisition cost and overall TCO of any competing solution. > http://p.sf.net/sfu/whatsupgold-sd > _______________________________________________ > MonetDB-users mailing list > MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net> > <mailto:MonetDB-users@lists.sourceforge.net <mailto:MonetDB-users@lists.sourceforge.net>> > https://lists.sourceforge.net/lists/listinfo/monetdb-users > > > > > -- > George Garbis > > > >
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------------------------------------------------------------------------------ WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd _______________________________________________ MonetDB-users mailing list MonetDB-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/monetdb-users
-- George Garbis