sumeetgajjar commented on a change in pull request #35047:
URL: https://github.com/apache/spark/pull/35047#discussion_r779813781
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
##########
@@ -3380,6 +3380,17 @@ object SQLConf {
.checkValue(_ >= 0, "The value must be non-negative.")
.createWithDefault(8)
+ val HASHED_RELATION_REORDER_FACTOR =
buildConf("spark.sql.hashedRelationReorderFactor")
+ .doc("The HashedRelation will be reordered if the number of unique keys
times this factor is " +
+ "less than equal to the total number of rows in the HashedRelation. " +
+ "The reordering places all rows with the same key adjacent to each other
to improve " +
+ "spatial locality. This provides a performance boost while iterating
over the rows for a " +
+ "given key due to increased cache hits")
+ .version("3.3.0")
+ .doubleConf
+ .checkValue(_ > 1, "The value must be greater than 1.")
+ .createOptional
Review comment:
As per the SQL benchmarks (not the micro-benchmark) that I ran, 4 is a
good default value for this config.
A value of 4 reduces the query processing time to half.
This was not set at query level but at the spark application level.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
