Github user klinvill commented on a diff in the pull request:
https://github.com/apache/spark/pull/16746#discussion_r98706364
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/jdbc/TeradataDialect.scala ---
@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.jdbc
+
+import java.sql.Types
+import org.apache.spark.sql.types._
+
+
+private case object TeradataDialect extends JdbcDialect {
+
+ override def canHandle(url: String): Boolean = {
url.startsWith("jdbc:teradata") }
+
+ override def getJDBCType(dt: DataType): Option[JdbcType] = dt match {
+ case StringType => Some(JdbcType("VARCHAR(255)",
java.sql.Types.VARCHAR))
+ case BooleanType => Option(JdbcType("CHAR(1)", java.sql.Types.CHAR))
+ case _ => None
+ }
--- End diff --
Hi @dongjoon-hyun,
Teradata still doesn't support LIMIT (it uses TOP instead) but the spark
code that was originally using limit has been changed to use "where 1=0
instead".
```
/**
* Get the SQL query that should be used to find if the given table
exists. Dialects can
* override this method to return a query that works best in a particular
database.
* @param table The name of the table.
* @return The SQL query to use for checking the table.
*/
def getTableExistsQuery(table: String): String = {
s"SELECT * FROM $table WHERE 1=0"
}
/**
* The SQL query that should be used to discover the schema of a table.
It only needs to
* ensure that the result set has the same schema as the table, such as
by calling
* "SELECT * ...". Dialects can override this method to return a query
that works best in a
* particular database.
* @param table The name of the table.
* @return The SQL query to use for discovering the schema.
*/
@Since("2.1.0")
def getSchemaQuery(table: String): String = {
s"SELECT * FROM $table WHERE 1=0"
}
```
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