Oracle Data Guard: Difference between revisions

Revision as of 15:35, 29 October 2015

Revision as of 15:36, 29 October 2015

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Logical standby databases convert the redo generated at the primary database into data and SQL and then re-apply those SQL transactions on the logical standby. Thus, physical structures and organization will be different from the primary database. Users can read from logical standby databases while the changes are being applied and, if the GUARD is set to STANDBY (ALTER DATABASE GUARD STANDBY;), write to tables in the logical standby database that are not being maintained by SQL Apply.

Unfortunately there are a number upportedof '''unsupported objects''' (e.g. tables or sequences owned by SYS, tables that use table compression, tables that underlie a materialized view or Global temporary tables (GTTs)) and '''unsupported data types''' (i.e.: datatypes BFILE, ROWID, and UROWID, user-defined TYPEs, multimedia data types like Oracle Spatial, ORDDICOM, and Oracle Text Collections (e.g. nested tables, VARRAYs), SecureFile LOBs, OBJECT RELATIONAL XMLTypes and BINARY XML).<ref>

{{cite web

| url = http://www.databasejournal.com/features/oracle/article.php/3860251/Leveraging-Logical-Standby-Databases-in-Oracle-11g-Data-Guard.htm