Metabases are repositories of database tables and objects that define, enable, and manage data distribution replication projects. Metabases contain change data capture (replication) backlogs and metadata about what tables are enabled for capture on the source, allowing Connect replication projects to connect to the source databases and retrieve the necessary schemas and tables needed for the projects.
Db2 for IBM i, Db2 for LUW, Oracle, and SQL Server JDBC data connections used for a replication project must be associated with a metabase. You create metabases in Connect to be saved on the database server accessed by the JDBC data connection. Metabases are stored in the database on the source system. Each metabase for Db2 for IBM i and Db2 for LUW connections is assigned a journal and that journal is associated with a log reader. Each time replication project changes are committed, information is written to the metabase. The metabase includes:
- XML metadata files accessible to all the replication components.
- One or more indexes, views, trigger tables,and data replication backlog tables. The backlog tables contain changed data updates by column that are linked together by row, table, and transaction ID, queued (waiting) to be replicated.
- The status and number of tables that are enabled for capture.
- Information about the replication project, stored in memory.