In Oracle Database, LOB can be stored in line or out of line. If the LOB data is less than 4000 bytes, then it can be stored in line or on the same database page as the rest of the row data. This means Oracle GoldenGate can capture from the redo log. If LOB data is larger than 4000 bytes, LOB data is stored out of line. Oracle GoldenGate will fetch the data from the database. Fetching operation is in general slower than capturing from the redo log.
Oracle GoldenGate in general captures Secure File LOB from redo log . However, if the SECUREFILE LOBs are de-duplicated in 11g, modified using DBMS_LOB.FRAGMENT_* procedures or NOLOGGING LOBs is used, Oracle GoldenGate then needs to fetch the data from the source table. Again, fetching operation is in general slower than capturing from the redo log. ch the data from the source table.[2]
Oracle GoldenGate captures from redo log.
- Oracle GoldenGate Documenation (12.2) - 1.6.7 Large Object Data Types
- Oracle GoldenGate Documentation (12.2) - 1.5 Summary of Supported Oracle Data Types and Objects Per Capture Mode