Metadata

Basic

• Target table schema: The schema on the target to which the source tables will be replicated if you do not want to use the source table schema (or if there is no schema in the source database).

  Information noteWhen replicating to an Oracle target, the default target table schema is "system". Note also that if you leave this field empty (in which case the source schema will be used), you must make sure that the source schema already exists on the target. Otherwise, the task will fail.
  Information noteThe maximum permitted length for the schema name is 128 characters.

Replicate LOB columns

• Do not include LOB columns: Select this if you do not want source LOB columns to be replicated.

• Limit LOB column size to (KB): This is the default. Select this option if you only need to replicate small LOBs or if the target platform does not support unlimited LOB size. The maximum permitted value for this field is 102400 KB (100 MB).

  When replicating small LOBs, this option is more efficient than the Allow unlimited LOB size option since the LOBs are replicated "inline" as opposed to via "lookup" from the source. During Change Processing, small LOBs are usually replicated via "lookup" from the source.

  As the value of the Limit LOB size to is in bytes, the size should be calculated according to the following formulas:

  • BLOB: The length of the largest LOB.
  • NCLOB: The length of the longest TEXT in characters multiplied by two (as each character is handled as a double-byte). If the data includes 4-byte characters, multiply it by four.
  • CLOB: The length of the longest TEXT in characters (as each character is handled as a UTF8 character). If the data includes 4-byte characters, multiply it by two.
  Information note

  • Any LOBs larger than the specified size will be truncated.
  • During Change Processing from Oracle source, inline BLOBs are replicated inline.
  • Changes to this setting will only affect existing tables after they are reloaded.

• Do not limit LOB column size: When this option is selected, LOB columns will be replicated, regardless of size.

  Information noteReplicating LOB columns may impact performance. This is especially true in the case of the large LOB columns which require Qlik Talend Data Integration to perform a lookup from the source table in order to retrieve the source LOB value.

  • Optimize when LOB size is less than: Select this option when you need to replicate both small and large LOBs, and most of the LOBs are small.

    Information note

    This option is supported with the following sources and targets only:

    • Sources: Oracle, Microsoft SQL server, MySQL, PostgreSQL, and IBM DB2 for LUW

    • Targets: Oracle, Microsoft SQL Server, MySQL, PostgreSQL.

    When this option is selected, during Full Load, the small LOBs will be replicated "inline" (which is more efficient), and the large LOBs will be replicated by performing a lookup from the source table. During Change Processing, however, both small and large LOBs will be replicated by performing a lookup from the source table.

    Information note

    When this option is selected, Qlik Talend Data Integration will check all of the LOB sizes to determine which ones to transfer "inline". LOBs larger than the specified size will be replicated using Full LOB mode.

    Therefore, if you know that most of the LOBs are larger than the specified setting, it is preferable to use the Replicate unlimited LOB columns option instead.

  • Chunk size (KB): Optionally, change the size of the LOB chunks to use when replicating the data to the target. The default chunk size should suffice in most cases, but if you encounter performance issues, adjusting the size may improve performance.

    Information note

    With some databases, data type validation occurs when the data is inserted or updated. In such cases, replication of structured data types (e.g. XML, JSON, GEOGRAPHY, etc.) may fail if the data is bigger than the specified chunk size.

Advanced

Control table settings

• Control tables schema: Specify the target schema for the Control Tables if you do not want them to be created in the source schema (the default), or in the target schema.

  Information noteThe maximum permitted length for the schema name is 128 characters.
• Create target control tables in tablespace: ​ When the replication target is Oracle, specify the tablespace where you want the target control tables to be created. If you do not enter any information in this field, the tables will be created in the default tablespace in the target database.
• Create indexes for target control tables in tablespace: When the replication target is Oracle, specify the tablespace where you want the control table indexes to be created. If you do not enter any information in this field, the indexes will be created in the same tablespace as the control tables.
• Replication history timeslot (minutes): The length of each time slot in the Replication history Control Table. The default is 5 minutes.

Control table selection