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
