feat: support grouping() and grouping_id() indicator functions#4815
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andygrove wants to merge 1 commit into
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feat: support grouping() and grouping_id() indicator functions#4815andygrove wants to merge 1 commit into
andygrove wants to merge 1 commit into
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Add SQL file test coverage for grouping/grouping_id with ROLLUP, CUBE, and GROUPING SETS, and mark both as supported in the expressions guide. These are Unevaluable expressions that the analyzer rewrites into arithmetic over the virtual spark_grouping_id column, so the constituent operators and expressions (ExpandExec, Cast, BitwiseAnd, ShiftRight, Literal) already run natively in Comet.
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Which issue does this PR close?
Closes #4814.
Rationale for this change
The
grouping()andgrouping_id()indicator functions used withROLLUP,CUBE, andGROUPING SETSwere marked as unsupported in the expressions guide. In practice they areUnevaluableexpressions that Spark's analyzer rewrites before physical planning:grouping(col)becomesCast(BitwiseAnd(ShiftRight(spark_grouping_id, n-1-i), 1L), ByteType)grouping_id()becomes a reference to thespark_grouping_idvirtual columnEvery constituent piece is already supported by Comet: the
ExpandExecoperator thatROLLUP/CUBE/GROUPING SETSlower to, plusCast,BitwiseAnd,ShiftRight, andLiteral. As a result these queries already run natively end-to-end, so no Scala serde or Rust work is required. This PR adds the missing test coverage and updates the documentation to reflect the actual support level.What changes are included in this PR?
spark/src/test/resources/sql-tests/expressions/aggregate/grouping.sqlcoveringgrouping(col)andgrouping_id()withCUBE,ROLLUP, andGROUPING SETS, multi-column grouping, the explicit-columngrouping_id(a, b)form, combinedgrouping+grouping_idusage, use inHAVING, and NULL input data.groupingandgrouping_idas supported (✅) indocs/source/user-guide/latest/expressions.md.This change was scaffolded using the
implement-comet-expressionskill.How are these changes tested?
The new SQL file test runs each query through both Spark and Comet in the default
querymode, which asserts that the whole plan executes natively on Comet (no fallback) and that results match Spark exactly. All queries pass: