[postgis-users] several SRID on one table

[Chris Hermansen]

Steve;

Do you have the concept of a "master" SRID?  In other words, is there a 
projection in which you do all of your maintenance / updates?

If so, you could consider keeping that as your "main" / "master" table, 
and either creating your other "tables" as views with on-the-fly 
projections from that table, or create the entries automatically in 
other tables using insert / update / delete triggers.

A problem to consider with keeping everything in one table is that the 
wider your rows, the more I/O you have to do to read and write rows.  So 
if you have application A reading SRID 1 and application B reading SRID 
2 you will probably find better throughput by physically separating the 
table.  Worth testing, anyway.

Also, with separate tables, especially tables that are not heavily 
maintained, you can try clustering your indexes to improve your performance.

Steve.Toutant at inspq.qc.ca wrote:
>
> Hello,
> We need to use a table for several purposes with different SRID.
> Is it a good practice to have several geometry columns on one table or 
> should we create one table per SRID?
> What are the pros and cons of using several geometry columns on one 
> table?
>
> thanks
> Steve
>
> /Steve Toutant, M. Sc./
> Analyste en géomatique
> Secteur environnement
> Direction des risques biologiques, environnementaux et occupationnels
> Institut national de santé publique du Québec
> 945, avenue Wolfe
> Québec, Qc G1V 5B3
>
> Tél.: (418) 650-5115 #5281
> Fax.: (418) 654-3144_
> __steve.toutant at inspq.qc.ca_ <mailto:steve.toutant at inspq.qc.ca>_
> __http://www.inspq.qc.ca_ <http://www.inspq.qc.ca/>
>
>  
>
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Chris Hermansen         mailto:chris.hermansen at timberline.ca
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