30. DataPumper
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## 30. DataPumper

### 30.1. Overview

The export and import features are useful if you cannot connect to the source and the target database at once. If your source and target are both reachable at the same time, it is more efficient to use the DataPumper to copy data between two systems. With the DataPumper no intermediate files are necessary. Especially with large tables this can be an advantage.

To open the DataPumper, select Tools → DataPumper

The DataPumper lets you copy data from a single table (or SELECT query) to a table in the target database. The mapping between source columns and target columns can be specified as well

Everything that can be done with the DataPumper, can also be accomplished with the `WbCopy` command. The DataPumper can also generate a script which executes the `WbCopy` command with the correct parameters according to the current settings in the window. This can be used to create scripts which copy several tables.

The DataPumper can also be started as a stand-alone application - without the main window - by specifying -datapumper=true in the command line when starting SQL Workbench/J.

When opening the DatPumper from the main window, the main window's current connection will be used as the initial source connection. You can disable the automatic connection upon startup with the property `workbench.datapumper.autoconnect` in the `workbench.settings` file.

### 30.2. Selecting source and target connection

The DataPumper window is divided in three parts: the upper left part for defining the source of the data, the upper right part for defining the target, and the lower part to adjust various settings which influence the way, the data is copied.

After you have opened the DataPumper window it will automatically connect the source to the currently selected connection from the main window. If the DataPumper is started as a separate application, no initial connection will be made.

To select the source connection, press the ellipsis right next to the source profile label. The standard connection dialog will appear. Select the connection you want to use as the source, and click OK. The DataPumper will then connect to the database. Connecting to the target database works similar. Simply click on the ellipsis next to the target profile box.

Instead of a database connection as the source, you can also select a text or XML file as the source for the DataPumper. Thus it can also be used as a replacement of the WbImport command.

The drop down for the target table includes an entry labeled "(Create new table)". For details on how to create a new table during the copy process please refer to the advanced tasks section.

After source and target connection are established you can specify the tables and define the column mapping between the tables.

### 30.3. Copying a complete table

To copy a single table select the source and target table in the dropdowns (which are filled as soon as the connection is established)

After both tables are selected, the middle part of the window will display the available columns from the source and target table. This grid display represents the column mapping between source and target table.

#### 30.3.1. Mapping source to target columns

Each row in the display maps a source column to a target column. Initially the DataPumper tries to match those columns which have the same name and data type. If no match is found for a target column, the source column will display `(Skip target column)` This means that the column from the target table will not be included when inserting data into the target table (technically speaking: it will be excluded from the column list in the INSERT statement).

#### 30.3.2. Restricting the data to be copied

You can restrict the number of rows to be copied by specifying a `WHERE` clause which will be used when retrieving the data from the source table. The `WHERE` clause can be entered in the SQL editor in the lower part of the window.

#### 30.3.3. Deleting all rows from the target table

When you select the option "Delete target table", all rows from the target table will be deleted before the copy process is started. This is done with a `DELETE FROM <tablename>;` When you select this option, make sure the data can be deleted in this way, otherwise the copy process will fail.

The `DELETE` will not be committed right away, but at the end of the copy process. This is obviously only of interest if the connection is not done with autocommit = true

#### 30.3.4. Continuing when an insert fails

In some cases inserting of individual rows in the target table might fail (e.g. a primary key violation if the table is not empty). When selecting the option "Continue on error", the copy process will continue even if rows fail to insert

#### 30.3.5. Committing changes

By default all changes are committed at the end, when all rows have been copied. By supplying a value in the field "Commit every" SQL Workbench/J will commit changes every time the specified number of rows has been inserted into the target. When a value of 50 rows has been specified, and the source table contains 175 rows, SQL Workbench/J will send 4 `COMMIT`s to the target database. After inserting row 50, row 100, row 150 and after the last row.

#### 30.3.6. Batch execution

If the JDBC driver supports batch updates, you can enable the use of batch updates with this check box. The check box will be disabled, if the JDBC driver does not support batch updates, or if a combined update mode (insert,update, update,insert) is selected.

Batch execution is only available if either INSERT or UPDATE mode is selected.

#### 30.3.7. Update mode

Just like the WbImport and WbCopy commands, the data pumper can optionally update the data in the target table. Select the approriate update strategy from the `Mode` drop down. The DataPumper will use the key columns defined in the column mapper to generate the `UPDATE` command. When using update you have to select at least one key column.

You cannot use the update mode, if you select only key columns, The values from the source are used to build up the `WHERE` clause for the `UPDATE` statement. If ony key columns are defined, then there would be nothing to update.

For maximum performance, choose the update strategy that will result in a successful first statement more often. As a rule of thumb:

- Use `-mode=insert,update`, if you expect more rows to be inserted then updated.
- Use `-mode=update,insert`, if you expect more rows to be updated then inserted.

### 30.4. Advanced copy tasks

#### 30.4.1. Populating a column with a constant

To populate a target column with a constant value. The name of the source columns can be edited in order to supply a constant value instead of a column name. Any expression understood by the source database can be entered there. Note that if (Skip target column) is selected, the field cannot be edited.

#### 30.4.2. Creating the target table

You can create the target table "on the fly" by selecting `(Create target table)` from the list of target tables. You will be prompted for the name of the new table. If you later want to use a different name for the table, click on the button to the right of the drop down.

The target table will be created without any primary key definitions, indexes of foreign key constraints.

The DataPumper tries to map the column types from the source columns to data types available on the target database. For this mapping it relies on information returned from the JDBC driver. The functions used for this may not be implemented fully in the driver. If you experience problems during the creation of the target tables, please create the tables manually before copying the data. It will work best if the source and target system are the same (e.g. PostgreSQL to PostgreSQL, Oracle to Oracle, etc).

Most JDBC drivers map a single JDBC data type to more then one native datatype. MySql maps its `VARCHAR`, `ENUM` and `SET` type to java.sql.Types.VARCHAR. The DataPumper will take the first mapping which is returned by the driver and will ignore all subsequent ones. Any datatype that is returned twice by the driver is logged as a warning in the log file. The actual mappings used, are logged with type INFO.

To customize the mapping of generic JDBC datatypes to DBMS specific datatypes, please refer to Customizing data type mapping

#### 30.4.3. Using a query as the source

If you want to copy the data from several tables into one table, you can use a SELECT query as the source of your data. To do this, select the option `Use SQL query as source` below the SQL editor. After you have entered you query into the editor, click the button Retrieve columns from query. The columns resulting from the query will then be put into the source part of the column mapping. Make sure, the columns are named uniquely when creating the query. If you select columns from different tables with the same name, make sure you use a column alias to rename the columns.

Creating the target table "on the fly" is not available when using a SQL query as the source of the data

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