Parquet Dictionary Predicate Pushdown Fixes#13594
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zhenxiao merged 2 commits intoprestodb:masterfrom Oct 24, 2019
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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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@pettyjamesm does this fix #13457 ? |
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Unlikely, the query referenced in that issue has no predicates and the bug it does fix was introduced in 0.174 |
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Oct 24, 2019
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nice catch, @pettyjamesm
This was referenced Nov 11, 2019
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Port of trinodb/trino#1846.
Parquet dictionary pushdown was refactored in #6892 to remove a nested loop iteration but accidentally left the inner loop break statement 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.