Paul, Good thought.
Let's see. The default blocking used by the GeoRaster driver is (256, 256, 1). That is good because GeoTiffs doesn't tile on band space. So I would imagine that if I tiled the GeoTiff this way: [EMAIL PROTECTED]:~/Data> time gdal_translate Barcelona_2007_R2C2.TIF Barcelona_2007_R2C2_tiled.TIF -co BLOCKXSIZE=256 -co BLOCKYSIZE=256 Input file size is 14336, 14336 0...10...20...30...40...50...60...70...80...90...100 - done. real 0m42.991s user 0m20.289s sys 0m2.516s The comparison would be fair: [EMAIL PROTECTED]:~/Data> time gdal_translate Barcelona_2007_R2C2_tiled.TIF out2.tif -srcwin 0 0 2000 2000 Input file size is 14336, 14336 0...10...20...30...40...50...60...70...80...90...100 - done. real 0m1.604s user 0m1.156s sys 0m0.444s What do you think? I would imagine that if I run gdaladdo to add Pyramids on the GeoRaster one application could take advantage of it by telling Oracle to cache the BLOB in memory. So the next time a user zoom-in the performance would be even better. I am trying to setup a mapserver experiment on that issue but for now I would like to keep my analysis on that very simple process of extracting a subset. Best regards, Ivan > -------Original Message------- > From: Paul Ramsey <[EMAIL PROTECTED]> > Subject: Re: [OSGeo-Discuss] Raster data on RDBMS > Sent: Oct 29 '08 05:00 > > The data is chunked in Oracle into tiles, so unless you tile the TIFF > as well you aren't really doing a direct comparison. Even if you end > up with the same numbers for both processes, I'll still be impressed, > since I assumed Oracle would have a higher overhead. > > P. > > On Tue, Oct 28, 2008 at 9:54 PM, Lucena, Ivan <[EMAIL PROTECTED]> wrote: > > Hi There, > > > > I would like to return to a discussion that we had months ago about raster > on RDBMS. But this time I would like to present some number. > > > > As long as I could recall there was basically two major arguments contrary > to storing raster on RDBMS. One very pragmatical: "Why waste precious process > time with the overhead of dealing with queries, tables, client-sever back and > forth just to get the data from BLOB fields on a database when you can get it > directly from the file system?". The other argument was semantical: "Why > store raster on RDBMS if in general we are not expecting to have a > transactions on that data?" > > > > I cannot argue against the second one. I basically agreed with that but > after seeing how fragile and complicated even a well defined structure of > folders and files could be I would vote in favor of the good and old > relational model. > > > > That is my experiment. I downloaded two free data samples from Naveteq > website. Two geotiff files with the same size and number of bands (14336, > 14336, 3): > > > > [EMAIL PROTECTED]:~/Data> du -k Barcelona_2007_R2C2.TIF > > 602828 Barcelona_2007_R2C2.TIF > > [EMAIL PROTECTED]:~/Data> du -k San_Francisco_2006_R1C2.TIF > > 602828 San_Francisco_2006_R1C2.TIF > > > > Then I loaded those images to Oracle Spatial GeoRaster using GDAL. The > loading process is comparable than some commercial ETL products on the > market. It took about 2 minutes to load each image. > > > > [EMAIL PROTECTED]:~/Data> time gdal_translate -of georaster > Barcelona_2007_R2C2.TIF georaster:scott,tiger,orcl,RDT_2$,2 > > Input file size is 14336, 14336 > > 0...10...20...30...40...50...60...70...80...90...100 - done. > > Ouput dataset: (georaster:scott,tiger,orcl,RDT_2$,2) on GDAL_IMPORT,RASTER > > real 1m54.973s > > user 0m4.368s > > sys 0m1.936s > > > > If you are a Oracle GeoRaster users you might be excited about those > number already but those are not the numbers I want to show. What I would > like to do is to compare the time that it takes to extract subset from the > original geotiff and compare with the time to extract the same subset from > the RDBMS. He are the numbers: > > > > [EMAIL PROTECTED]:~/Data> time gdal_translate > georaster:scott,tiger,orcl,RDT_2$,2 out.tif -srcwin 0 0 2000 2000 > > Input file size is 14336, 14336 > > 0...10...20...30...40...50...60...70...80...90...100 - done. > > real 0m0.720s > > user 0m0.408s > > sys 0m0.108s > > > > [EMAIL PROTECTED]:~/Data> time gdal_translate Barcelona_2007_R2C2.TIF > out2.tif -srcwin 0 0 2000 2000 > > Input file size is 14336, 14336 > > 0...10...20...30...40...50...60...70...80...90...100 - done. > > real 0m1.177s > > user 0m0.976s > > sys 0m0.188s > > > > And I also checked the integrity of the results to see if I get the same > result: > > > > [EMAIL PROTECTED]:~/Data> gdalinfo -checksum out.tif > > ... > > Band 1 Block=2000x1 Type=Byte, ColorInterp=Red > > Checksum=58248 > > Band 2 Block=2000x1 Type=Byte, ColorInterp=Green > > Checksum=21226 > > Band 3 Block=2000x1 Type=Byte, ColorInterp=Blue > > Checksum=8002 > > > > [EMAIL PROTECTED]:~/Data> gdalinfo -checksum out2.tif > > ... > > Band 1 Block=2000x1 Type=Byte, ColorInterp=Red > > Checksum=58248 > > Band 2 Block=2000x1 Type=Byte, ColorInterp=Green > > Checksum=21226 > > Band 3 Block=2000x1 Type=Byte, ColorInterp=Blue > > Checksum=8002 > > > > What are others test would be interesting to perform? > > > > Best regards, > > > > Ivan > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > Discuss mailing list > > Discuss@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/discuss > > > _______________________________________________ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
