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Oracle Goldengate's thought sky--feeling the essence of Ogg
The title of this article, the high imitation of the white total "dba of the Mind of the sky-the understanding of Oracle Database Essence", hey.
In this article, I would like to say that the understanding of Ogg is likely to be incorrect, and you are welcome to criticize.
1.OGG is data synchronization software, or logical replication software, its competitors have IBM Cdc,dell Shareplex,dsg,dds and so on.
2.OGG software is required to be installed on the operating system, Oracle DB software does not have its own OGG software (at least for now)
3.OGG software has three major processes (say four processes also line):
Three major processes: source extraction process, source transfer process, destination application process (i.e.: replication process)
Four processes: Source extraction process, source transfer process, destination server process (responsible for writing trail files on destination), destination application process (i.e., replication process)
There are two types of trail file for 4.OGG software
Trail file at Source: written by the source extraction process.
Destination Trail File: The source transfer process is transmitted to the destination, and the server process on the destination is written to the destination operating system under the specified path.
The three major processes in 5.OGG software have their own checkpoint (i.e. checkpoint, which is used to record where each process is read and where it is written)
Source extraction process: Read checkpoint and write checkpoint.
SOURCE transfer process: There are read checkpoints and write checkpoints.
Destination application process: have read Check point
The process of handling trail file in the three major processes of 6.OGG software:
Source extraction Process: Read the Oracle Redo log (assuming the source database is Oracle), combined with the extraction process parameter file, the contents of the redo log into Ogg-formatted file (that is: Trail file), and written to the source operating system under the specified path
SOURCE transfer process: Read the "source extraction process Write Trail file", in conjunction with the transfer process parameters file, send the data that needs to be synchronized to the destination, at the destination is the server process responsible for writing.
Destination application process: Read the trail file under the specified path of the destination operating system, and combine the application process's parameter file to form an SQL statement that executes these SQL statements on the destination DB.
