Hi, Written down notes from discussion about which flags should be enabled by default in the next 5.3 release: - Derived tables and keys in them should be enabled - BKA should not be enabled (doesn't make sense for 'default' query loads) - semi-joins should be enabled - Materialization (base) should be enabled - extra strategies for NULL-aware materialization - ??? - ICP should be enabled - Hash join could be enabled but in the next minor release. - Cost-based MRR should not be enabled as cost model is not tuned. when some feature is considered stable enough, its owner should apply for testing with {$current_optimizer_switch_default+new_feature}, and once that is passed, change the default in the main branch. BR Sergey -- Sergei Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog