fix: preserve byte-size statistics in AggregateExec #18885
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Tamar-Posen
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Thanks for opening the PR! I fired the tests |
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Hey @Dandandan, could you retrigger the tests? |
Tamar-Posen
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Nov 23, 2025
| assert_snapshot!( | ||
| pretty_format_batches(&sql_results).unwrap(), | ||
| @r" | ||
| +---------------+-------------------------------------------------------------------------------------------------------------------------+ |
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The physical plan changed bc join selection now uses available byte stats.
Which leads to a more optimal join order - ensuring the smaller side is chosen as the build side.
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Done |
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Same here @Dandandan, @alamb - could one of you please retrigger the CI? (Unless there’s a way for me to do it myself?) |
Previously, AggregateExec dropped total_byte_size statistics (Precision::Absent) through aggregation operations, preventing the optimizer from making informed decisions about memory allocation and execution strategies(join side selection -> dynamic filters). This commit implements proportional byte-size scaling based on row count ratios: - Added calculate_scaled_byte_size helper with inline optimization - Scales byte size for Final/FinalPartitioned without GROUP BY - Scales byte size proportionally for all other aggregation modes - Always returns Precision::Inexact for estimates (semantically correct) - Returns Precision::Absent when insufficient input statistics Added test coverage for edge cases (absent statistics, zero rows).
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Dandandan
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@Dandandan Thanks for the review! |
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Previously, AggregateExec dropped total_byte_size statistics (Precision::Absent) through aggregation operations, preventing the optimizer from making informed decisions about memory allocation and execution strategies(join side selection -> dynamic filters).
This commit implements proportional byte-size scaling based on row count ratios:
Added test coverage for edge cases (absent statistics, zero rows).
Which issue does this PR close?
#18850
Rationale for this change
Without byte-size statistics, the optimizer cannot estimate memory requirements for join-side selection, dynamic filter generation, and memory allocation decisions. This preserves statistics using proportional scaling (bytes_per_row × output_rows).
What changes are included in this PR?
statistics_innerto calculate proportional byte size instead of returningPrecision::Absentcalculate_scaled_byte_sizehelper (inline optimized, guards against division by zero)Are these changes tested?
Yes:
test_aggregate_statistics_edge_casescovers edge cases scenariosAre there any user-facing changes?
No breaking changes.
Internal optimization that may improve query planning and provide more accurate memory estimates in EXPLAIN output.