Manager:-
The Manager process must be running on both the
source as well as target systems before the Extract or Replicat process can be
started and performs several functions including monitoring and starting other
GoldenGate processes, managing the trail files and also reporting.
Extract:-
The Extract process runs on the source system and
is the data capture mechanism of GoldenGate. It can be configured both for the initial loading of the source data as well as to synchronize the changed data
on the source with the target. This can be configured to also propagate any DDL
changes on those databases where DDL change support is available.
Replicat:-
The Replicat process runs on the target system and
reads transactional data changes as well as DDL changes and replicates then to
the target database. Like the Extract process, the Replicat process can also be
configured for Initial Load as well as Change Synchronization.
Collector:-
The Collector is a background process which runs on
the target system and is started automatically by the Manager (Dynamic
Collector) or it can be configured to start manually (Static Collector). It
receives extracted data changes that are sent via TCP/IP and writes then to the
trail files from where they are processed by the Replicat process.
Trails:-
Trails are series of files that GoldenGate
temporarily stores on disks and these files are written to and read from by the
Extract and Replicat processes. Depending on the configuration chosen, these
trail files can exist on the source as well as on the target systems. If it
exists on the local system, it will be known an Extract Trail or as Remote
Trail if it exists on the target system.
Data Pumps:-
Data Pumps are secondary extract mechanisms which
exist in the source configuration. This is optional component and if Data Pump
is not used then Extract sends data via TCP/IP to the remote trail on the
target. When Data Pump is configured, the Primary Extract process will write to
the Local Trail and then this trail is read by the Data Pump and data is sent
over the network to Remote Trails on the target system.
In the absence of Data Pump, the data that the
Extract process extracts resides in memory alone and there is no storage of
this data anywhere on the source system. In case of network of target failures,
there could be cases where the primary extract process can abort or abend. Data
Pump can also be useful in those cases where we are doing complex filtering and
transformation of data as well as when we are consolidating data from many
sources to a central target.
Data source:-
When processing transactional data changes, the
Extract process can obtain data directly from the database transaction logs
(Oracle, DB2, SQL Server, MySQL etc) or from a GoldenGate Vendor Access Module
(VAM) where the database vendor (for
example Teradata) will provide the required components that will be used by
Extract to extract the data changes.
Groups:-
To differentiate between the number of different
Extract and Replicat groups which can potentially co-exist on a system, we can
define processing groups. For instance, if we want to replicate different sets
of data in parallel, we can create two Replicat groups.
A processing group consists of a process which
could be either a Extract or Replicat process, a corresponding parameter file,
checkpoint file or checkpoint table (for Replicat) and other files which could
be associated with the process.
