Rule based optimizations
openLooKeng supports one rule based optimization, described below.
Join Conversion
Inner-join is a mature operation with great efficiency in our newest version. To utilize the advantage, the semi-join queries can be converted to inner-join for better performance.
With rule-based join conversion, openLooKeng automatically converts the semi-join query to inner-join with equal purpose.
The join conversion is governed by the rewrite_filtering_semi_join_to_inner_join session property, with optimizer.rewrite-filtering-semi-join-to-inner-join configuration property providing the default value.
The valid values are:
true- enable join conversionfalse(default) - disable join conversion
Ranking with TopNRankingNumberNode
Ranking operation is optimized with predicate with TopNRankingNumberNode. It boosted the performance greatly on ranking queries.
The TopNRankingNumberNode ranking is governed by the optimize_top_n_ranking_number session property, with optimizer.optimize-top-n-ranking-function configuration property providing the default value.
The valid values are:
true(default) - enable ranking withTopNRankingNunmberNodefalse- disable ranking withTopNRankingNumberNode