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https://issues.apache.org/jira/browse/SPARK-10849?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apache Spark reassigned SPARK-10849:
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Assignee: Apache Spark
> Allow user to specify database column type for data frame fields when writing
> data to jdbc data sources.
> ---------------------------------------------------------------------------------------------------------
>
> Key: SPARK-10849
> URL: https://issues.apache.org/jira/browse/SPARK-10849
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 1.5.0
> Reporter: Suresh Thalamati
> Assignee: Apache Spark
> Priority: Minor
>
> Mapping data frame field type to database column type is addressed to large
> extent by adding dialects, and Adding maxlength option in SPARK-10101 to
> set the VARCHAR length size.
> In some cases it is hard to determine max supported VARCHAR size , For
> example DB2 Z/OS VARCHAR size depends on the page size. And some databases
> also has ROW SIZE limits for VARCHAR. Specifying default CLOB for all String
> columns will likely make read/write slow.
> Allowing users to specify database type corresponding to the data frame field
> will be useful in cases where users wants to fine tune mapping for one or two
> fields, and is fine with default for all other fields .
> I propose to make the following two properties available for users to set in
> the data frame metadata when writing to JDBC data sources.
> database.column.type -- column type to use for create table.
> jdbc.column.type" -- jdbc type to use for setting null values.
> Example :
> val secdf = sc.parallelize( Array(("Apple","Revenue ..."),
> ("Google","Income:123213"))).toDF("name", "report")
> val metadataBuilder = new MetadataBuilder()
> metadataBuilder.putString("database.column.type", "CLOB(100K)")
> metadataBuilder.putLong("jdbc.type", java.sql.Types.CLOB)
> val metadta = metadataBuilder.build()
> val secReportDF = secdf.withColumn("report", col("report").as("report",
> metadata))
> secReporrDF.write.jdbc("jdbc:mysql://<URL>/secdata", "reports", mysqlProps)
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