[GitHub] [spark] huaxingao commented on a diff in pull request #36556: [SPARK-39162][SQL][3.3] Jdbc dialect should decide which function could be pushed down

[GitBox <gi...@apache.org>]

huaxingao commented on code in PR #36556:
URL: https://github.com/apache/spark/pull/36556#discussion_r873942747


##########
sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala:
##########
@@ -240,8 +240,27 @@ abstract class JdbcDialect extends Serializable with Logging{
         getJDBCType(dataType).map(_.databaseTypeDefinition).getOrElse(dataType.typeName)
       s"CAST($l AS $databaseTypeDefinition)"
     }
+
+    override def visitSQLFunction(funcName: String, inputs: Array[String]): String = {
+      if (isSupportedFunction(funcName)) {
+        s"""$funcName(${inputs.mkString(", ")})"""
+      } else {
+        // The framework will catch the error and give up the push-down.
+        // Please see `JdbcDialect.compileExpression(expr: Expression)` for more details.
+        throw new UnsupportedOperationException(
+          s"${this.getClass.getSimpleName} does not support function: $funcName")
+      }
+    }
   }
 
+  /**
+   * Returns whether the database supports function.
+   * @param funcName Upper-cased function name
+   * @return True if the database supports function.
+   */
+  @Since("3.3.0")

Review Comment:
   Let's hope this can still make RC2.



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