# RFC 13: Improved Feature Insertion/Update/Delete Performance in Batch Mode

    Author: Konstantin Baumann

    Contact: konstantin.baumann@hpi.uni-potsdam.de

    Status: Withdrawn

Withdrawn

I have withdrawn this RFC based on some comments from Frank and Tamas on GDAL-dev.

Summary

Some OGR drivers can dramatically increase the speed of and optimize the insertion, update, and deletion of a set of features, if the driver knows, that there is a whole set of features that should/could be inserted, updated, or deleted at once (instead of just one by one).

CreateFeatures()

The following new virtual method is added to the OGRLayer class, with an analogous C function:

    virtual OGRErr CreateFeatures( OGRFeature** papoFeatures, int iFeatureCount );

A default implementation is given as below:

    OGRErr OGRLayer::CreateFeatures(
        OGRFeature **papoFeatures,
        int iFeatureCount
    ) {
        for(int i = 0; i < iFeatureCount; ++i) {
            OGRErr error = CreateFeature( papoFeatures[i] );
            if( error != OGRERR_NONE ) return error;
        }
        return OGRERR_NONE;
    }

This triggers the old behavior of an unoptimized insertion.

Individual drivers can override the default implementation and can implement an optimized algorithm for inserting a set of features.

SetFeatures()

The following new virtual method is added to the OGRLayer class, with an analogous C function:

    virtual OGRErr SetFeatures( OGRFeature** papoFeatures, int iFeatureCount );

A default implementation is given as below:

    OGRErr OGRLayer::SetFeatures(
        OGRFeature **papoFeatures,
        int iFeatureCount
    ) {
        for(int i = 0; i < iFeatureCount; ++i) {
            OGRErr error = SetFeature( papoFeatures[i] );
            if( error != OGRERR_NONE ) return error;
        }
        return OGRERR_NONE;
    }

This triggers the old behavior of an unoptimized update.

Individual drivers can override the default implementation and can implement an optimized algorithm for updating a set of features.

DeleteFeatures()

The following new virtual method is added to the OGRLayer class, with an analogous C function:

    virtual OGRErr DeleteFeatures( long *panFIDs, int iFIDCount );

A default implementation is given as below:

    OGRErr OGRLayer::DeleteFeatures(
        long *panFIDs,
        int iFIDCount
    ) {
        for(int i = 0; i < iFIDCount; ++i) {
            OGRErr error = DeleteFeature( panFIDs[i] );
            if( error != OGRERR_NONE ) return error;
        }
        return OGRERR_NONE;
    }

This triggers the old behavior of an unoptimized deletion.

Individual drivers can override the default implementation and can implement an optimized algorithm for deleting a set of features.

C API functions

The following C functions are added:

    OGRErr OGR_L_CreateFeatures( OGRFeature** papoFeatures, int iFeatureCount );
    OGRErr OGR_L_SetFeatures( OGRFeature** papoFeatures, int iFeatureCount );
    OGRErr OGR_L_DeleteFeatures( long* panFIDs, int iFIDCount );

However, there are some issues with adding plain C arrays to the public OGR interface due to the SWIG based wrapping, see for example GDAL-Dev Mail from Tamas...

Additional Notes

Based in this new interface functions, I was able to increase the insertion speed of features in the MySQL driver from 40 per second to up to 800-2000 per second. I think other drivers can benefit from this change, too.

See also ticket #1633.

Implementation Plan

A patch for the describe additions can be trivially provided.

I can provide another patch based on this interface which contains the optimized implementation for the MySQL driver.

History

14-May-2007: initial version created

15-May-2007: SetFeatures() added

16-May-2007: DeleteFeatures() added

17-May-2007: C API functions added; SWIG wrapping issues mentioned

23-May-2007: Withdrawn due some concerns on GDAL-dev