[mapserver-users] logging GDAL queries

[Lucena, Ivan]

Sebastian,

Sebastian E. Ovide wrote:
> Hi Ivan,
> 
> 
> 
>     Because of that, to access your GeoRaster object, the GDAL driver is
>     requesting a very large array of BLOB (1000000 approximately). T
> 
> 
> I do not know how <apServer/GDAL works, but I cannot understand this query: 
> 
> 
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40] SELECT RASTERBLOCK
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40] FROM   
> RDT_FLUVD04Q200PJ
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40] WHERE  RASTERID = 
> :1 AND
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40]        
> PYRAMIDLEVEL = :3
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40] ORDER BY
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40]        
> BANDBLOCKNUMBER ASC,
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40]        
> ROWBLOCKNUMBER ASC,
> [Fri Aug 13 13:53:00 2010] [error] [client 10.0.1.40]        
> COLUMNBLOCKNUMBER ASC
> 
> It looks like  MapServer/GDAL is trying to read the whole pyramid level 
> X of the table RDT_FLUVD04Q200PJ ? 
> 
> Am I right ?
> 
> at level 0 it would read the whole raster !!!!
> 

Yes!

and

No!

That query creates a *cursor* to go through the whole raster, meaning, all the rows on the 
RasterDataTable that satisfy that query in the order stipulated by it.

It does require a some memory but it looks like you got it. Right? I assuming that because you said 
that gdal_translate loaded those 51 Gb in 5 minutes.

By the way, how long does it take to produce a geotiff file? Have loaded that image on QuantumGIS 
using the oracle_raster plugin? Hoes does it perform?

> I was expecting to find in the logs some query that reads a subset of 
> the whole image (just the tile/metatile that MapServer is serving) for 
> example using SDO_GEOR.getRasterSubset.. 

That would be very slow. The GDAL driver access the BLOB directly.

I have more questions:

Are you using Mapserver FastCGI with a recent version?

If you do, them the process will remains in memory, the GDALDataset associated with that GeoRaster 
will be keet, the *cursor* you remain alive and all the zooms and pans are going to work faster. 
Like for QGIS. Unless, of course, Mapserver is feeling the need to re-project or produce a new 
overview tiles on the fly. Can you see that on the log?

Regards,

Ivan