[gdal-dev] VRT performance Improvement

[jratike80]

Hi,

I guess that the slowest part is not VRT but your SQL
SELECT * FROM "features" WHERE LegendEntryName 
    IN("V_XX_AR","V_XX_LB","V_DOCIND_PT","V_XX_ML") because GeoJSON does not
support attribute indexes. I would have a try by converting GeoJSON into
GeoPackage or any other database format. Remember to create the index as
well

ogrinfo -sql "create index legendentryname_idx on my_table(legententryname)"
my_geopackage.gpkg

Running attribute queries without index is so expensive that it is waste of
time to begin to optimize anything else. I do not know if GDAL has methods
for creating temporary attribute indexes so that you would not need to
convert GeoJSON physically into some other format.

-Jukka Rahkonen-


MRRAJESH wrote
> Developers,
> 
> We are using VRT file (located in physical disk) as input to
> GDALVectorTranslate in C++. This VRT file pointing JSON file, which is
> little bigger size. How to improve the performance?
> 
>          const char *pszFilename = "C:\\Test\\MVT.vrt";	
>          hSrcDS = (GDALDatasetH *)GDALOpenEx(pszFilename,
> GDAL_OF_READONLY, NULL,NULL, NULL);
> 
>          dst = (GDALDataset *)GDALVectorTranslate(vsibuf, NULL, 1,
> &hSrcDS, opt,NULL);
> 
> *VRT FILE:*
> 
> OGRVRTDataSource>
>   
> <OGRVRTLayer name="Administrative">
>     
> <SrcDataSource relativeToVRT="1">
> features.json
> </SrcDataSource>
>     
> <SrcSQL dialect="sqlite">
> SELECT * FROM "features" WHERE LegendEntryName 
>     IN("V_XX_AR","V_XX_LB","V_DOCIND_PT","V_XX_ML")
> </SrcSQL>
>    
> </OGRVRTLayer>
> .....
> ....
> 
> 
> Regards,
> Rajesh
> 
> 
> 
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