[SPARK-59056][SQL] Pre-size HashSets in ParquetFilters IN/InSet pushdown - #58349
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[SPARK-59056][SQL] Pre-size HashSets in ParquetFilters IN/InSet pushdown#58349david-mollitor-db wants to merge 1 commit into
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`ParquetFilters.makeInPredicate` builds a `java.util.HashSet` for each IN predicate pushed down to Parquet and then adds exactly `values.length` elements. The sets start at the default capacity (16) and rehash as they grow. Pre-size each of the 12 sets from the known element count with Guava's `Sets.newHashSetWithExpectedSize(values.length)` so they hold all IN values without rehashing or reallocating the internal bucket array. The Guava helper is used rather than `new HashSet(values.length)` because `java.util.HashSet`'s int constructor treats the argument as bucket capacity, not expected size, so the naive form would still rehash past ~75% load. This mirrors the existing `Maps.newHashMapWithExpectedSize` usage in sql/catalyst.
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What changes were proposed in this pull request?
ParquetFilters.makeInPredicatebuilds ajava.util.HashSetfor eachINpredicate pushed down to Parquet, then adds exactly
values.lengthelements toit. The sets are created without an initial capacity, so they start at the
default capacity (16) and rehash as they grow.
This PR pre-sizes each of those 12 sets from the known element count using
Guava's
Sets.newHashSetWithExpectedSize(values.length), so they hold allINvalues without rehashing or reallocating the internal bucket array.
The Guava helper is used rather than
new HashSet(values.length)becausejava.util.HashSet's int constructor treats the argument as bucket capacity,not expected size, so the naive form would still rehash once the set passes
~75% load. This mirrors the existing
Maps.newHashMapWithExpectedSizeusage insql/catalyst.Why are the changes needed?
makeInPredicateis only reached when theINlist size exceedsspark.sql.parquet.pushdown.inFilterThreshold(default 10); smaller lists takea per-element equality OR-chain and never build a
HashSet. So by constructionthe set always holds more than the threshold's worth of values, and for larger
INlists (dozens to thousands) the default-capacity set rehashes several timesper pushed-down predicate, allocating and discarding bucket arrays, once per
Parquet file split scanned. Pre-sizing removes that avoidable work. The change
is capacity-only and behavior-preserving.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
Existing
ParquetV1FilterSuite, which coversIN/InSetpredicate pushdown,passes. The change is capacity-only, so predicate semantics are unchanged.
Was this patch authored or co-authored using generative AI tooling?
Generated-by: Claude Opus 4.8