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

    Author: Konstantin Baumann[[BR]]
    Contact: baumann@hpi.uni-potsdam.de[[BR]]
    Status: Proposed 

'''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( OGRFeature** papoFeatures, int iFeatureCount );
}}}

A default implementation is given as below:
{{{
OGRErr OGRLayer::DeleteFeatures(
    OGRFeature **papoFeatures,
    int iFeatureCount
) {
    for(int i = 0; i < iFeatureCount; ++i) {
        OGRErr error = DeleteFeature( papoFeatures[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.

'''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[[BR]]
15-May-2007: !SetFeatures() added[[BR]]
16-May-2007: !DeleteFeatures() added[[BR]]