Enabling large object data types to be writable after upgrading

After you upgrade, the large object data types of your remote data sources are mapped to CLOB, BLOB, or DBCLOB data types, depending on the data source that you are accessing.

About this task

With the exception of the Oracle NET8 wrapper and the DRDA wrapper, federated servers cannot write to Db2® CLOB, BLOB, or DBCLOB data types in nicknames.

If you need to write to these large object data types after you upgrade, you can alter the local CLOB and BLOB data type columns to VARCHAR and VARCHAR FOR BIT DATA data types.

You can alter CLOB and BLOB data types to VARCHAR data types with lengths up to 32672 bytes. If the CLOB, BLOB, or DBCLOB data type contains data that is larger than 32672 bytes, the data is truncated.

To enable replication of large object data types, you must allow write operations on these large object data type columns. Db2 replication requires insert and update privileges on the column values that it replicates to target tables.

To allow write operations on large object data types:

Procedure

Issue the ALTER NICKNAME statement.

For example:

ALTER NICKNAME nickname1
      ALTER COLUMN column1
       LOCAL TYPE VARCHAR(32672)

You might receive SQL statement warnings when you attempt to alter large object data types depending on the size of the data and the data source that you are accessing.