[mapserver-users] logging GDAL queries

[Sebastian E. Ovide]

Ivan,



> 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.


mmm... that makes me little bit nervous... I am testing it with a small map.
Its is only UK with 5mx5m pixel.... Just wondering how this approach would
scale to larger maps... US is 40 times bigger than UK... and they have more
accurated maps.... and more than a single layer.... Just wondering how many
manual configuration I'll be forced to do.... (Oracle created Spatial
extention exactly for this reason... so the developer do not to think about
handling blobs for him self anymore... reducing costs and risks)


>
> 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?
>
>
it is not possible to create a TIFF as it would be too big (max size is
4GB)... and UK would be arounf 16GB (300MB in Oracle as I'm using deflate)

I am testing Oracle MapViewer on the same table and it HAS the same
problem.... The strange thing is that using MapBuilder (Oracle software to
prepare the maps to use with MapViewer) the maps are displayed very fast at
ANY zoom level !... therefore there is a way to do it fast (as MapBuilder
does...)


>
>  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.
>

not sure about that... well I guess that at least it releases some work from
the Oracle server...  Anyway, as I have a spatial index, why don't just
query only the right blobs?


> I have more questions:
>
> Are you using Mapserver FastCGI with a recent version?
>
>
nop... I have not tried that yet... I'll try on Monday... I have tried as
cgi and recently as mod_python.


> 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
>
>
regards


-- 
Sebastian E. Ovide
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