Internally, the Capture mechanism or
architecture has four main components: Reader server; Preparer
server; Builder server; and Capture process.
Each Reader server, Preparer server, and
Builder server is a parallel execution server. The Capture
process (Cnnn) is an Oracle background process.
Reader Server: Reads the redo log
file and divides the log into multiple regions.
One or more Preparer Servers: Scan
the regions defined by the Reader server in parallel and sends
information about objects and schema changes to the rules
Builder Servers: Merges redo records
from the preparer servers and evaluates them. It does initial
The following section presents details on
how the Capture process works.
After receiving the merged records from the
preparer servers, the Capture process: