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From "Apache Spark (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (SPARK-7478) Add a SQLContext.getOrCreate to maintain a singleton instance of SQLContext
Date Fri, 08 May 2015 08:28:00 GMT

     [ https://issues.apache.org/jira/browse/SPARK-7478?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Apache Spark reassigned SPARK-7478:
-----------------------------------

    Assignee: Apache Spark  (was: Tathagata Das)

> Add a SQLContext.getOrCreate to maintain a singleton instance of SQLContext
> ---------------------------------------------------------------------------
>
>                 Key: SPARK-7478
>                 URL: https://issues.apache.org/jira/browse/SPARK-7478
>             Project: Spark
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Tathagata Das
>            Assignee: Apache Spark
>            Priority: Blocker
>
> Having a SQLContext singleton would make it easier for applications to use a lazily instantiated
single shared instance of SQLContext when needed. It would avoid problems like 
> 1. In REPL/notebook environment, rerunning the line {{val sqlContext = new SQLContext}}
multiple times created different contexts while overriding the reference to previous context,
leading to issues like registered temp tables going missing.
> 2. In Streaming, creating SQLContext directly leads to serialization/deserialization
issues when attempting to recover from DStream checkpoints. See [SPARK-6770]. Also to get
around this problem I had to suggest creating a singleton instance - https://github.com/apache/spark/blob/master/examples/src/main/scala/org/apache/spark/examples/streaming/SqlNetworkWordCount.scala
> This can be solved by {{SQLContext.getOrCreate}} which get or creates a new singleton
instance of SQLContext using either a given SparkContext or a given SparkConf



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