HIVE-26238: Decouple sort filter predicates optimization from digest normalization in CBO #3299
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kgyrtkirk
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Jun 1, 2022
It doesn't really matter if we change the order of predicates in the WHERE clause of an SQL query (JdbcFilter) since in most cases the underlying JDBC engine will decide the evaluation order.
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Oct 28, 2022
…normalization in CBO (Stamatis Zampetakis, reviewed by Zoltan Haindrich) 1. Decouple sort filter optimization from digest normalization by refactoring HiveSortFilterPredicates into a (DFS) visitor. We cannot use planner or rules cause they make use of digest. Performing this optimization using a visitor slightly simplifies the code since there is no need to have a registry since we are not going to visit the same node twice. 2. Move the optimization after all post-join transformations to avoid having other optimizations cancel the benefit of the sort filter predicates. Closes apache#3299
dengzhhu653
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Dec 15, 2022
…normalization in CBO (Stamatis Zampetakis, reviewed by Zoltan Haindrich) 1. Decouple sort filter optimization from digest normalization by refactoring HiveSortFilterPredicates into a (DFS) visitor. We cannot use planner or rules cause they make use of digest. Performing this optimization using a visitor slightly simplifies the code since there is no need to have a registry since we are not going to visit the same node twice. 2. Move the optimization after all post-join transformations to avoid having other optimizations cancel the benefit of the sort filter predicates. Closes apache#3299
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What changes were proposed in this pull request and why?
Decouple sort filter optimization from digest normalization by refactoring
HiveSortFilterPredicatesinto a (DFS) visitor. We cannot use planner or rules cause they make use of digest. Performing this optimization using a visitor slightly simplifies the code since there is no need to have a registry since we are not going to visit a node twice.Move the optimization after all post-join transformations to avoid having other optimizations cancel the benefit of the sort filter predicates. As shown by the plan changes here, now we can see some additional cases where the optimization is effective and wasn't done previously.
Does this PR introduce any user-facing change?
Possibly more efficient plan in certain cases.
How was this patch tested?
Existing CBO tests by enabling (0091373), disabling (7567730) normalization and checking plan changes.