[1571] Fix COUNT(*) aggregate queries to use metadata-only optimization for .show() command
#1643
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scottsand-db
commented
Mar 9, 2023
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| protected def getDeltaScanGenerator(index: TahoeLogFileIndex): DeltaScanGenerator | ||
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| /** Return the number of rows in the table or `None` if we cannot calculate it from stats */ | ||
| private def extractGlobalCount(tahoeLogFileIndex: TahoeLogFileIndex): Option[Long] = { |
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vkorukanti
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Mar 13, 2023
core/src/test/scala/org/apache/spark/sql/delta/perf/OptimizeMetadataOnlyDeltaQuerySuite.scala
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core/src/test/scala/org/apache/spark/sql/delta/perf/OptimizeMetadataOnlyDeltaQuerySuite.scala
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zsxwing
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Mar 15, 2023
core/src/test/scala/org/apache/spark/sql/delta/perf/OptimizeMetadataOnlyDeltaQuerySuite.scala
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| val showPlans = DeltaTestUtils.withLogicalPlansCaptured(spark, optimizedPlan = true) { | ||
| spark.sql(s"SELECT COUNT(*) FROM $testTableName").show() | ||
| } | ||
| assert(showPlans.collect { case x: LocalRelation => x }.size === 1) |
core/src/main/scala/org/apache/spark/sql/delta/perf/OptimizeMetadataOnlyDeltaQuery.scala
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zsxwing
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Mar 17, 2023
allisonport-db
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Mar 21, 2023
Previously, metadata-only aggregate pushdown was only working for `COUNT(*)` queries when you were collecting the result, as opposed to calling `.show()`. This PR fixes that bug.
Added a UT that captures the optimized logical plan and checks that it is using the LocalRelation created by OptimizeMetadataOnlyDeltaQuery.
Also did a performance test locally. Created a table with 100M rows and 100K files and ran the query `sql("SELECT COUNT(*) FROM <delta-table>").show()`
- master took ms ~161 seconds.
- this PR took ~16 seconds. Thus, this is a ~10x improvement.
Resolves delta-io#1571.
Closes delta-io#1643
Signed-off-by: Scott Sandre <[email protected]>
GitOrigin-RevId: e266e5d82220ca331e117f202abc6f085a99448c
(cherry picked from commit 48388b9)
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Description
Resolves #1571. Previously, metadata-only aggregate pushdown was only working for
COUNT(*)queries when you were collecting the result, as opposed to calling.show(). This PR fixes that bug.How was this patch tested?
Added a UT that captures the optimized logical plan and checks that it is using the LocalRelation created by OptimizeMetadataOnlyDeltaQuery.
Also did a performance test locally. Created a table with 100M rows and 100K files and ran the query
sql("SELECT COUNT(*) FROM <delta-table>").show()