Indexes on nicknames in a federated database
You can also create a text index on nicknames in a federated database that
points to tables in a remote database. In this case, the role of the log table
(for incremental index updates) differs from its role for an index on a regular
table. Unlike regular tables, DB2 triggers can not be created on nicknames,
so that change information about documents can not be inserted into a log
table using triggers. Therefore, there are two different ways for incremental
updates to create an index on a nickname:
- The log table is created locally in the federated database and the application
is responsible that the log table contains correct change information on the
nickname. For DB2 views, this is similar to the incremental index update.
This option is the default option.
- DB2 Replication has been set up so that changes to the table referenced
by the nickname are captured in a so-called "Change Data Table" (CD-table)
for DB2 remote databases, or a "Consistent Change Data Table" (CCD-table)
for non-DB2 relational databases. DB2 Net Search Extender can then use the
CD or CCD table instead of creating a log table for an index on a nickname.
In this case, you must specify the capture table characteristics in the DB2TEXT
CREATE INDEX command.