core: Make NDV non-zero #1985
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core: Make NDV non-zero #1985
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joshua-spacetime
approved these changes
Nov 12, 2024
Centril
approved these changes
Nov 12, 2024
2 tasks
gefjon
approved these changes
Nov 13, 2024
Change `TxId::num_distinct_values` to return `Option<NonZeroU64>`. It will now return `None` if either the table doesn't exist, no index exists for the given column list, or the index is empty. Otherwise, `Some` non-zero number of distinct values is returned. Fixes a division-by-zero bug in the query row estimation.
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Change
TxId::num_distinct_valuesto returnOption<NonZeroU64>.It will now return
Noneif either the table doesn't exist, no indexexists for the given column list, or the index is empty.
Otherwise,
Somenon-zero number of distinct values is returned.Fixes a division-by-zero bug in the query row estimation.
Expected complexity level and risk
1
Testing
No functional change,
estimation::index_row_estis now statically guaranteedto not panic due to division-by-zero