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[SPARK-37001][SQL] Disable two level of map for final hash aggregation by default #34270

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[SPARK-37001][SQL] Disable two level of map for final hash aggregation by default #34270

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255daac
Disable two level map for final hash aggregation by default
c21 Oct 13, 2021
d02f108
Address all comments
c21 Oct 13, 2021
889adbe
Address all comments and fix unit test failure
c21 Oct 14, 2021
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14 changes: 13 additions & 1 deletion sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1705,11 +1705,21 @@ object SQLConf {
.doc("Enable two-level aggregate hash map. When enabled, records will first be " +
"inserted/looked-up at a 1st-level, small, fast map, and then fallback to a " +
"2nd-level, larger, slower map when 1st level is full or keys cannot be found. " +
"When disabled, records go directly to the 2nd level.")
"When disabled, records go directly to the 2nd level. Enable for partial aggregate only.")
.version("2.3.0")
.booleanConf
.createWithDefault(true)

val ENABLE_TWOLEVEL_FINAL_AGG_MAP =
buildConf("spark.sql.codegen.aggregate.final.map.twolevel.enabled")
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@cloud-fan cloud-fan Oct 13, 2021

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how about park.sql.codegen.aggregate.map.twolevel.partialOnly

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@c21 c21 Oct 13, 2021

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@cloud-fan - sure, updated. So given the new meaning of config, changed the default config value to true as well.

.internal()
.doc("Enable two-level aggregate hash map for final aggregate as well. Disable by default " +
"because final aggregate might get more distinct keys compared to partial aggregate. " +
"Overhead of looking up 1st-level map might dominate when having a lot of distinct keys.")
.version("3.2.0")
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@cloud-fan cloud-fan Oct 13, 2021

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3.2.1

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@c21 c21 Oct 13, 2021

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@cloud-fan - yes, updated.

.booleanConf
.createWithDefault(false)

val ENABLE_VECTORIZED_HASH_MAP =
buildConf("spark.sql.codegen.aggregate.map.vectorized.enable")
.internal()
Expand Down Expand Up @@ -3865,6 +3875,8 @@ class SQLConf extends Serializable with Logging {

def enableTwoLevelAggMap: Boolean = getConf(ENABLE_TWOLEVEL_AGG_MAP)

def enableTwoLevelFinalAggMap: Boolean = getConf(ENABLE_TWOLEVEL_FINAL_AGG_MAP)

def enableVectorizedHashMap: Boolean = getConf(ENABLE_VECTORIZED_HASH_MAP)

def useObjectHashAggregation: Boolean = getConf(USE_OBJECT_HASH_AGG)
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9 changes: 8 additions & 1 deletion sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/HashAggregateExec.scala
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Expand Up @@ -667,7 +667,14 @@ case class HashAggregateExec(
val isNotByteArrayDecimalType = bufferSchema.map(_.dataType).filter(_.isInstanceOf[DecimalType])
.forall(!DecimalType.isByteArrayDecimalType(_))

isSupported && isNotByteArrayDecimalType
val isEnabledForAggModes =
if (modes.forall(mode => mode == Partial || mode == PartialMerge)) {
true
} else {
conf.enableTwoLevelFinalAggMap
}

isSupported && isNotByteArrayDecimalType && isEnabledForAggModes
}

private def enableTwoLevelHashMap(ctx: CodegenContext): Unit = {
Expand Down