Parquet Dictionary Predicate Pushdown Fixes#1846
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martint merged 2 commits intotrinodb:masterfrom Oct 24, 2019
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Thanks! I'll merge it once the tests pass
findepi
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presto-parquet/src/main/java/io/prestosql/parquet/predicate/PredicateUtils.java
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"Early" is no longer as clear as it was, since there is no "normal"
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nit: ideally code cleanup should go in separate commit
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nit: ideally code cleanup should go in separate commit
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Test failure is from a stuck container, don’t think it’s related to the changes but I haven’t had a chance to look harder yet. |
Commit 0f7982b refactored ParquetPredicateUtils.getDictionaries from getDictionariesByColumnOrdinal, removing a nested loop iteration but accidentally leaving in a break statement. The effect has been that at most 1 dictionary was returned from getDictionaries, limiting the effectiveness of predicate pushdown on dictionaries.
No more parquet dictionaries need to be read once a dictionary predicate pushdown check succeeds.
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Parquet dictionary pushdown was refactored in prestodb/presto#6892 to remove a nested loop iteration but accidentally left the inner loop
breakstatement behind. This meant that dictionary predicate pushdown would read at most 1 dictionary.In addition to fixing the pushdown behavior, this PR adds support for checking the dictionary pushdown on each column skipping additional dictionary reads once the block can already be filtered.