[jira] [Commented] (SPARK-16196) Optimize in-memory scan performance using ColumnarBatches
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https://issues.apache.org/jira/browse/SPARK-16196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16611633#comment-16611633
]
Kazuaki Ishizaki commented on SPARK-16196:
--
[~cloud_fan] This PR in the Jira entry proposes two fixes
# Read data in a table cache directry from a columnar storage
# Generate code to build a table cache
We already implemented 1. But, we have not implmented 2. yet. Let us address 2.
in the next release.
> Optimize in-memory scan performance using ColumnarBatches
> -
>
> Key: SPARK-16196
> URL: https://issues.apache.org/jira/browse/SPARK-16196
> Project: Spark
> Issue Type: Bug
> Components: SQL
>Affects Versions: 2.0.0
>Reporter: Andrew Or
>Assignee: Andrew Or
>Priority: Major
>
> A simple benchmark such as the following reveals inefficiencies in the
> existing in-memory scan implementation:
> {code}
> spark.range(N)
> .selectExpr("id", "floor(rand() * 1) as k")
> .createOrReplaceTempView("test")
> val ds = spark.sql("select count(k), count(id) from test").cache()
> ds.collect()
> ds.collect()
> {code}
> There are many reasons why caching is slow. The biggest is that compression
> takes a long time. The second is that there are a lot of virtual function
> calls in this hot code path since the rows are processed using iterators.
> Further, the rows are converted to and from ByteBuffers, which are slow to
> read in general.
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[jira] [Commented] (SPARK-16196) Optimize in-memory scan performance using ColumnarBatches
[
https://issues.apache.org/jira/browse/SPARK-16196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16611494#comment-16611494
]
Kazuaki Ishizaki commented on SPARK-16196:
--
I see. I will check this.
> Optimize in-memory scan performance using ColumnarBatches
> -
>
> Key: SPARK-16196
> URL: https://issues.apache.org/jira/browse/SPARK-16196
> Project: Spark
> Issue Type: Bug
> Components: SQL
>Affects Versions: 2.0.0
>Reporter: Andrew Or
>Assignee: Andrew Or
>Priority: Major
>
> A simple benchmark such as the following reveals inefficiencies in the
> existing in-memory scan implementation:
> {code}
> spark.range(N)
> .selectExpr("id", "floor(rand() * 1) as k")
> .createOrReplaceTempView("test")
> val ds = spark.sql("select count(k), count(id) from test").cache()
> ds.collect()
> ds.collect()
> {code}
> There are many reasons why caching is slow. The biggest is that compression
> takes a long time. The second is that there are a lot of virtual function
> calls in this hot code path since the rows are processed using iterators.
> Further, the rows are converted to and from ByteBuffers, which are slow to
> read in general.
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[jira] [Commented] (SPARK-16196) Optimize in-memory scan performance using ColumnarBatches
[
https://issues.apache.org/jira/browse/SPARK-16196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16610702#comment-16610702
]
Wenchen Fan commented on SPARK-16196:
-
I believe it has been fixed, [~kiszk] can you confirm?
> Optimize in-memory scan performance using ColumnarBatches
> -
>
> Key: SPARK-16196
> URL: https://issues.apache.org/jira/browse/SPARK-16196
> Project: Spark
> Issue Type: Bug
> Components: SQL
>Affects Versions: 2.0.0
>Reporter: Andrew Or
>Assignee: Andrew Or
>Priority: Major
>
> A simple benchmark such as the following reveals inefficiencies in the
> existing in-memory scan implementation:
> {code}
> spark.range(N)
> .selectExpr("id", "floor(rand() * 1) as k")
> .createOrReplaceTempView("test")
> val ds = spark.sql("select count(k), count(id) from test").cache()
> ds.collect()
> ds.collect()
> {code}
> There are many reasons why caching is slow. The biggest is that compression
> takes a long time. The second is that there are a lot of virtual function
> calls in this hot code path since the rows are processed using iterators.
> Further, the rows are converted to and from ByteBuffers, which are slow to
> read in general.
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[jira] [Commented] (SPARK-16196) Optimize in-memory scan performance using ColumnarBatches
[
https://issues.apache.org/jira/browse/SPARK-16196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15348703#comment-15348703
]
Apache Spark commented on SPARK-16196:
--
User 'andrewor14' has created a pull request for this issue:
https://github.com/apache/spark/pull/13899
> Optimize in-memory scan performance using ColumnarBatches
> -
>
> Key: SPARK-16196
> URL: https://issues.apache.org/jira/browse/SPARK-16196
> Project: Spark
> Issue Type: Bug
> Components: SQL
>Affects Versions: 2.0.0
>Reporter: Andrew Or
>Assignee: Andrew Or
>
> A simple benchmark such as the following reveals inefficiencies in the
> existing in-memory scan implementation:
> {code}
> spark.range(N)
> .selectExpr("id", "floor(rand() * 1) as k")
> .createOrReplaceTempView("test")
> val ds = spark.sql("select count(k), count(id) from test").cache()
> ds.collect()
> ds.collect()
> {code}
> There are many reasons why caching is slow. The biggest is that compression
> takes a long time. The second is that there are a lot of virtual function
> calls in this hot code path since the rows are processed using iterators.
> Further, the rows are converted to and from ByteBuffers, which are slow to
> read in general.
--
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