[postgis-users] [!! SPAM] Re: may have postgis store limits for a big project?

[salas]

Hi, this topic is very interesting but in my situation we need to know about
the vectorial data, not storing of raster data.
could someone tell me about this? store limits for vectorial data.

yuriesky

----- Original Message ----- 
From: "Pierre Racine" <Pierre.Racine at sbf.ulaval.ca>
To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
Sent: Monday, July 19, 2010 10:25 AM
Subject: [!! SPAM] Re: [postgis-users] may have postgis store limits for a
big project?


> >We do not know yet.. it could be even hundreds !
>
> WKT Raster is not really limited in size. But we still have to test on
> datasets the size you are using.
>
>>each region (european country, US state, province, etc...) would have few
>>raster (even 20) >representing different kind of information... (each
>>pixel would be 5mx5rm)...
>
> With WKT Raster, you can store all those rasters as a unique tiled
> coverage. In Oracle probably you stored them one table per raster?
>
>>and I need to know the value of a pixel for all the rasters in that
>>particular coordinates...
>
> For this you typically use ST_Value() like this:
>
> SELECT ST_Value(rast, ST_Geomfromtext('Point(-78.1 58.1)', 4326))
> FROM srtm_tiled_100x100
> WHERE ST_Intersects(rast::geometry, ST_Geomfromtext('Point(-78.1 58.1)',
> 4326))
>
> One query like this takes 16 milliseconds on my machine on a 100 pixels x
> 100 pixels tiled coverage. There are 46800 tiles.
>
> Don't forget to assign a reference system to your raster when converting
> it to .sql (-s gdal2wktraster's option) and to construct an index on the
> table (-I option).
>
>>with Oracle 11g GEORaster it is possible to compress the rasters (and get
>>lower performance of >course)... in my case the compression rate is up to
>>600 !!!... so the amount of data is >drastically reduced...
>
> WKT Raster relies on PostgreSQL for compression. I don't know the
> compression rate.
>
>>nevertheless I need to be able to do a few (up to 20) queries like this at
>>the same time in in a >fraction of second...: select pixel from raster
>>where (x=X and y=Y). One query for each raster, >representing a different
>>information
>
> If you tile and index everything properly that should not be a big deal.
> Let us know!
>
>>If WKTRaster is mature enough, we can create a cluster without the need of
>>paying a prohibitive license per CPU as for Oracle !
>
> If you save extra money by not having buying an Oracle license and you are
> interested in collaborating in the development of WKT Raster, let us know
> ;-)
>
> Pierre
>
> Sebastian
> On Mon, Jul 19, 2010 at 5:00 PM, Pierre Racine
> <Pierre.Racine at sbf.ulaval.ca> wrote:
> Hi Sebastian,
>
> What kind of query are you planning on the raster? You know you can also
> use WKT Raster to simply "register" filesystem rasters, creating a king of
> geospatial catalog, without actually storing them in the database...
>
> How many 16GB raster do you have? Are your raster all representing the
> same theme? Are they overlapping (or they form a regular grid)?
>
> We don't know of that many users cases up to now, but WKT Raster prooved
> to be very stable working on 1 GB raster coverage (see the tutorial).
>
> Pierre
>
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
> Sebastian E. Ovide
> Sent: 19 juillet 2010 11:34
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] may have postgis store limits for a big
> project?
>
> Hi All,
>
> I am interesting too... I am considering PostGIS+WKTRaster instead of
> Oracle GeoRaster... but for that can happen, Postgresql must be able of
> managing some simple tables of 30+M (Millions) rows plus a lot of Rasters
> of 16GB each... (16GB not compress data... so are huge images !). Each
> query (simple look up) must response in a fraction of second....
>
> any successful case ?
>
> Thanks !
> On Fri, Jul 16, 2010 at 1:13 AM, salas <fsalas at geocuba.cu> wrote:
> Hello to all:
> I am working in a project where they are managed more than 20 geoespatials
> thematics. Each thematic one has a considerable volume of since
> information it is of the whole country (I am speaking of a lot more than a
> million of records). In the project we need to make (mostly) intersection
> consultations keeping in mind literal attributes.
> I need to know the experience of somebody in a project of this span and if
> PostGIS would present some limitation therewith.
>
> regards yuriesky
>
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> --
> Sebastian E. Ovide
>
>
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> Sebastian E. Ovide
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