PreSQL is an SQL command that runs against a Hive source before the mapping reads from the source.

For example, you might use a Hive source in a mapping. The data stored in the Hive source changes regularly and you must update the data in the Hive source before the mapping reads from the source to make sure that the mapping reads the latest records. To update the Hive source, you can configure a PreSQL command.

PostSQL is an SQL command that runs against a Hive source after the mapping writes to the target.

For example, you might use a Hive source in a mapping. After the mapping writes to a target, you might want to delete the stage records stored in the Hive source. You want to run the command only after the mapping writes the data to the target to make sure that the data is not removed prematurely from the Hive source. To delete the records in the Hive source table after the mapping writes to the target, you can configure a PostSQL command.

Consider the following restrictions when you run PreSQL and PostSQL commands against Hive sources:

When you create an SQL override on a Hive source, you must enclose keywords or special characters in backtick (`) characters.
When you run a mapping with a Hive source in the Hadoop environment, references to a local path in pre-mapping SQL commands are relative to the Data Integration Service node. When you run a mapping with a Hive source in the native environment, references to local path in pre-mapping SQL commands are relative to the Hive server node.