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https://issues.apache.org/jira/browse/SPARK-29185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17090252#comment-17090252
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Shashanka Balakuntala Srinivasa commented on SPARK-29185:
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Hi, is there anyone working on this issue? If not i will take this up.
> Add new SaveMode types for Spark SQL jdbc datasource
>
>
> Key: SPARK-29185
> URL: https://issues.apache.org/jira/browse/SPARK-29185
> Project: Spark
> Issue Type: New Feature
> Components: SQL
>Affects Versions: 3.1.0
>Reporter: Timothy Zhang
>Priority: Major
>
> It is necessary to add new SaveMode for Delete, Update, and Upsert, such as:
> * SaveMode.Delete
> * SaveMode.Update
> * SaveMode.Upsert
> So that Spark SQL could support legacy RDBMS much betters, e.g. Oracle, DB2,
> MySQL etc. Actually code implementation of current SaveMode.Append types is
> very flexible. All types could share the same savePartition function, add
> only add new getStatement functions for Delete, Update, Upsert with SQL
> statements DELETE FROM, UPDATE, MERGE INTO respectively. We have an initial
> implementations for them:
> {code:java}
> def getDeleteStatement(table: String, rddSchema: StructType, dialect:
> JdbcDialect): String = {
> val columns = rddSchema.fields.map(x => dialect.quoteIdentifier(x.name) +
> "=?").mkString(" AND ")
> s"DELETE FROM ${table.toUpperCase} WHERE $columns"
> }
> def getUpdateStatement(table: String, rddSchema: StructType, priKeys:
> Seq[String], dialect: JdbcDialect): String = {
> val fullCols = rddSchema.fields.map(x => dialect.quoteIdentifier(x.name))
> val priCols = priKeys.map(dialect.quoteIdentifier(_))
> val columns = (fullCols diff priCols).map(_ + "=?").mkString(",")
> val cnditns = priCols.map(_ + "=?").mkString(" AND ")
> s"UPDATE ${table.toUpperCase} SET $columns WHERE $cnditns"
> }
> def getMergeStatement(table: String, rddSchema: StructType, priKeys:
> Seq[String], dialect: JdbcDialect): String = {
> val fullCols = rddSchema.fields.map(x => dialect.quoteIdentifier(x.name))
> val priCols = priKeys.map(dialect.quoteIdentifier(_))
> val nrmCols = fullCols diff priCols
> val fullPart = fullCols.map(c =>
> s"${dialect.quoteIdentifier("SRC")}.$c").mkString(",")
> val priPart = priCols.map(c =>
> s"${dialect.quoteIdentifier("TGT")}.$c=${dialect.quoteIdentifier("SRC")}.$c").mkString("
> AND ")
> val nrmPart = nrmCols.map(c =>
> s"$c=${dialect.quoteIdentifier("SRC")}.$c").mkString(",")
> val columns = fullCols.mkString(",")
> val placeholders = fullCols.map(_ => "?").mkString(",")
> s"MERGE INTO ${table.toUpperCase} AS ${dialect.quoteIdentifier("TGT")} " +
> s"USING TABLE(VALUES($placeholders)) " +
> s"AS ${dialect.quoteIdentifier("SRC")}($columns) " +
> s"ON $priPart " +
> s"WHEN NOT MATCHED THEN INSERT ($columns) VALUES ($fullPart) " +
> s"WHEN MATCHED THEN UPDATE SET $nrmPart"
> }
> {code}
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