[fdo-users] postgis and performance

[Traian Stanev]

Hi Zac,

The string matching would only be done if MapGuide actually accesses the column. It does do a select *, but it does not necessarily access every column, so the string comparisons is only an overhead for columns that it actually uses for generating the map image.

Traian


> -----Original Message-----
> From: fdo-users-bounces at lists.osgeo.org [mailto:fdo-users-
> bounces at lists.osgeo.org] On Behalf Of Zac Spitzer
> Sent: Monday, July 28, 2008 3:12 AM
> To: FDO Users Mail List
> Subject: Re: [fdo-users] postgis and performance
>
> On Mon, Jul 28, 2008 at 5:07 PM, alucas <alucas at srtec.com> wrote:
> >
> > Hi zac,
> >
> > But... Views are more slowly than tables. The best choice would be to
> change
> > the provider to avoid this string matching.
>
> views are pretty much zero cost, especially when compared to the
> string matching,
> which I completely agree with you on,
>
> but for instant gratification(tm) views will do it for you
>
> >
> > Regards.
> >
> >
> > zspitzer wrote:
> >>
> >> For better performance, try using views on your tables which only
> >> expose the minimal
> >> set of columns you require.
> >>
> >> Mapguide does "select * from table" which slows things down a lot,
> >> because each column
> >> is accessed via name rather than index and that's a lot of string
> >> matching..
> >>
> >> http://trac.osgeo.org/mapguide/ticket/272
> >>
> >> i.e. with a 500k row table, each additional column is now involved
> in
> >> another 500k of string matches
> >>
> >> Regards
> >>
> >> Zac
> >>
> >> On Sat, Jul 26, 2008 at 1:09 AM, alucas <alucas at srtec.com> wrote:
> >>>
> >>> Hello List,
> >>>
> >>> I'm testing postgis to store some Gregraphic layers and publish
> this data
> >>> to
> >>> the internet via Mapguide Enterprise 2009. I've performance
> problems to
> >>> publish some large volumes of vector data. For example, mapguide
> can't
> >>> preview (with Autodesk Mapguide Studio) one layer with 140.000
> records. I
> >>> need to publish some layers with aprox 500.000 records
> >>>
> >>> So, I need to manage large volume data sets with postgis and
> mapguide and
> >>> I've some questions:
> >>>
> >>> - In the unit tests for the postgis provider, what are the volumes
> of
> >>> data
> >>> tested?
> >>> - I've loaded the data into postgis via shp2pgsql. I don't know if
> the
> >>> default database created via shp2pgsql is the best for the postgis
> >>> provider
> >>> performance. It's possible to improve the database performance for
> >>> example
> >>> creating some gist indexes? If yes, how can I create the optimal
> index to
> >>> achieve the best performance in queries?
> >>>
> >>> To summarize, I need some help for optimize my postgis datastore...
> >>>
> >>> Some useful information about the system:
> >>>
> >>> MGE 2009
> >>> Autodesk Mapguide Studio 2009
> >>> Postgis 8.2.9
> >>> Postgis 1.3.3
> >>> FDO provider for postgis: 3.3.0 (Downloaded from GeoMap web page)
> >>>
> >>> Thanks in advance.
> >>>
> >>>
> >>> --
> >>> View this message in context:
> >>> http://www.nabble.com/postgis-and-performance-
> tp18653591p18653591.html
> >>> Sent from the FDO Users mailing list archive at Nabble.com.
> >>>
> >>> _______________________________________________
> >>> fdo-users mailing list
> >>> fdo-users at lists.osgeo.org
> >>> http://lists.osgeo.org/mailman/listinfo/fdo-users
> >>>
> >>
> >>
> >>
> >> --
> >> Zac Spitzer -
> >> http://zacster.blogspot.com (My Blog)
> >> +61 405 847 168
> >> _______________________________________________
> >> fdo-users mailing list
> >> fdo-users at lists.osgeo.org
> >> http://lists.osgeo.org/mailman/listinfo/fdo-users
> >>
> >>
> >
> > --
> > View this message in context: http://www.nabble.com/postgis-and-
> performance-tp18653591p18685149.html
> > Sent from the FDO Users mailing list archive at Nabble.com.
> >
> > _______________________________________________
> > fdo-users mailing list
> > fdo-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/fdo-users
> >
>
>
>
> --
> Zac Spitzer -
> http://zacster.blogspot.com (My Blog)
> +61 405 847 168
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