[
https://issues.apache.org/jira/browse/SPARK-23309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16350901#comment-16350901
]
Thomas Graves commented on SPARK-23309:
---------------------------------------
I should ask is there a log statement or query plan I can dump out just to make
sure spark.sql.inMemoryColumnarStorage.enableVectorizedReader=false was applied
properly?
> Spark 2.3 cached query performance 20-30% worse then spark 2.2
> --------------------------------------------------------------
>
> Key: SPARK-23309
> URL: https://issues.apache.org/jira/browse/SPARK-23309
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.3.0
> Reporter: Thomas Graves
> Priority: Blocker
>
> I was testing spark 2.3 rc2 and I am seeing a performance regression in sql
> queries on cached data.
> The size of the data: 10.4GB input from hive orc files /18.8 GB cached/5592
> partitions
> Here is the example query:
> val dailycached = spark.sql("select something from table where dt =
> '20170301' AND something IS NOT NULL")
> dailycached.createOrReplaceTempView("dailycached")
> spark.catalog.cacheTable("dailyCached")
> spark.sql("SELECT COUNT(DISTINCT(something)) from dailycached").show()
>
> On spark 2.2 I see queries times average 13 seconds
> On the same nodes I see spark 2.3 queries times average 17 seconds
> Note these are times of queries after the initial caching. so just running
> the last line again:
> spark.sql("SELECT COUNT(DISTINCT(something)) from dailycached").show()
> multiple times.
>
> I also ran a query over more data (335GB input/587.5 GB cached) and saw a
> similar discrepancy in the performance of querying cached data between spark
> 2.3 and spark 2.2, where 2.2 was better by like 20%.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
