Hi luchen.xu SubstitutionVisitor: based on pattern, and bottom-up visit. MaterializedViewRule: analyze semantics with relnode, such as SPJA
I have focused on the way of SubstitutionVisitor, let me talk about the advantages and disadvantages: Advantages: 1. Expand easily: you can define a custom pattern to match and rewrite the query's plan with mv. 2. Support out join: SubstitutionVisitor could pull-up condition under join. 3. Transcending the pattern of 'SPJA': SubstitutionVisitor support more pattern, such as: Sort, Union Disadvantages: 1. Not support compensate with union, which is implemented in 'MaterializedViewRule' 2. Affected by order of join, eg: query(a join b), mv(b join a) 3. Strong depending on normalization, such as project-pushdown, filter-pushdown. By the way, I have read the paper and code. MaterializedViewRule is limited to the pattern of 'SPJA', and the type of join must be inner-join. In my project, we have tried to expand it for the left-join case, and this work is going on. More relnode need be integrated into the MaterializedViewRule, such Sort. MaterializedViewRule has too long a way to go, we could discuss it continuously, and keep it better. I hope it could help you. Thanks XuRenhe 徐保荣 <[email protected]> 于2022年1月21日周五 11:04写道： > hello, > This problems keeps making me puzzled. > > question1: what is the differences between the two implemenrations > of view-based query rewriting?Advantages and disadvantages > based on view substitution( SubstitutionVisitor、rules:unifyrule） > Rewriting using plan structural information(rules:MaterializedViewRule) > > question2: Is there some materialized rewriting example where the first > one not work but the second work? if can list , very thanks > > I look forward to hearing from you very much > thanks > > > > > > rules transformation > Permalink > > >
