RFC 12: Improved File Management

Author: Konstantin Baumann
Contact: baumann@…
Status: Proposed

Summary

Some OGR drivers can dramatically increase the speed of and optimize the insertion of a set of features, if the driver knows, that there is a whole set of features that should/could be inserted 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.

Additional Notes

Based in this new interface function, 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.

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.