[GRASS-user] the performance of displaying vector attributes - with MySQL no difference!!

[Brent Wood]

Brad Douglas wrote:
> On Sun, 2006-11-12 at 20:12 +0100, perski at uranos.cto.us.edu.pl wrote:
>   
>> I spent some time on it during last days and I sucesfully introduced MySQL database to grass.
>> Unfortunately during displaying poits with colors from rgb columns THERE IS NO DIFFERENCE in performance comparing to dbf engine. After adding indexes to grassrgb column is still the same.
>>
>> Any other ideas hoe to speed up this task?
>>     
>
> There are a number of things that can be done to speed up database
> queries.  I suggest anyone who is using a true SQL database on the
> backend, learn how to successfully normalize the database.  Here are a
> few links about database normalization:
>
> http://en.wikipedia.org/wiki/Database_normalization
> http://dev.mysql.com/tech-resources/articles/intro-to-normalization.html
>
> Different databases take different approaches to administration and
> performance optimizations, but knowledge of SQL92 generally enough for
> successful normalization.
>
> I suspect that other columns in the query are the source of the slow
> down.
I suggest normalisation is a technique normally used for robust, largely 
error free database implementations. Once a properly normalised model 
has been devised, you then de-normalise the actual implementation as 
appropriate to improve performance.

You might try PostGIS, though I'm not sure if you still need to actually 
import the geometries into GRASS or can just utilise the external db. 
Postgres has largely caught up with MySQL for performance, and the 
PostGIS extension, last time I looked, was way ahead of MySQL spatial in 
functionality.

Also, are you sure you properly indexed the relevant data columns in MySQL?

Cheers,
  
  Brent Wood