Glossary of Terms

Certain terms are used during the installation and replication process. This section lists the common terms used and their description.

Term	Description
Source database	The database that contains the “source” data. This is the database that Dbvisit Replicate will be replicating FROM. This is also called the “MINE” database. The source database must always be Oracle.
Target database	The database that will be the “target” for the replicating. This is the database that Dbvisit Replicate will be replicating TO. This is also called the “APPLY” database.
MINE process	The MINE process reads the Oracle redo logs at the source database. The MINE process converts information from the Oracle redo log into a Dbvisit Replicate internal format called a PLOG.
	Example:
	To start the MINE process, the normal Dbvisit Replicate command is:
	dbvrep --daemon --ddcfile orcl.ddc start mine
	Where orcl.ddc is the DDC file (or configuration file) for a replication called orcl.
	In more complicated topologies, there can be more than one MINE process. Each MINE process will have a unique name which is determined by the user. Example: MINE, MINE2, etc.
APPLY process	The APPLY process takes the PLOG (created by the MINE process) and converts this information into SQL which can be run against the target database.
	Example:
	To start the APPLY process, the normal Dbvisit Replicate command is:
	dbvrep --daemon --ddcfile orcl.ddc start apply
	Where orcl.ddc is the DDC file (or configuration file) for a replication called orcl.
	There can be more than one APPLY process. Each APPLY process will have a unique name which is determined by the user. Example: APPLY, APPLY2, etc
Dbvisit Replicate Command Console	All Dbvisit Replicate commands are given through the Dbvisit Replicate Command Console (DRCC). To start the DRCC type:
	dbvrep
	To list progress of the replication:
	dbvrep> list progress
	To start the Dbvisit Replicate configure wizard:
	dbvrep> setup wizard
	To read and set the environment for a specific replication:
	dbvrep> readddc w112g.ddc
	(where w112g.ddc is the DDC file name)
	or:
	dbvrep --ddcfile orcl.ddc
FETCHER process	FETCHER is an optional component. It can be used to offload the mining of the source database to another server.
	Example:
	To start the FETCHER process, the normal Dbvisit Replicate command is:
	dbvrep --daemon --ddcfile orcl.ddc start fetcher
	Where orcl.ddc is the DDC file (or configuration file) for a replication called orcl.
	There can be more than one FETCHER process. Each FETCHER process will have a unique name which is determined by the user. Example: FETCHER, FETCHER2, etc.
PLOG	MINE reads oracle redo logs and creates PLOGs (parsed logs). These logs contain parsed information and are filtered to contain information about replicated tables only. PLOGs are binary logs specific to Dbvisit Replicate.
PLOG	The PLOGs are transferred to the target server where they are used by the APPLY process.
Source Server	The host or server that runs the source database. Dbvisit Replicate will be installed on this server.
Target Server	The host or server that runs the target database. Dbvisit Replicate will be installed on this server.
Install directory	The directory where Dbvisit Replicate will be installed.
ORACLE_HOME	The directory where the Oracle software or executables are installed.
TNS_ADMIN	The directory where the Oracle network configuration files are located (sqlnet.ora, tnsnames.ora)
Oracle software owner	This is the Windows user or account that owns the Oracle Software. In most cases this is oracle.
Dbvisit Database Configuration file (DDC)	A Dbvisit Replicated created text file which contains all the settings for the replication.
	The DDC file contains all the necessary configuration information for the replication. The file(s) will be in the Dbvisit Replicate install directory and has the format:
	replication_name.ddc
	Where replication_name is the name of the replication (which is in most cases the name of the source database).
	Contents of this file is by default stored in source database (called “DDC DB”) and the DDC file itself contains only credentials to this database.
	The DDC file must be manually copied to the target server.
Table key	Every row in a replicated table must be uniquely identifiable – in case of duplicates, APPLY would not be able to pick up the correct row to update/delete.
Table key	It is desirable that every replicated table has a primary key defined. If there is no primary key, then each row in the table must be uniquely identifiable.
Dbvisit Replicate schema	A dedicated schema in the replicated database (both source and target). Contains various pieces of information required for operation of Dbvisit Replicate.
	Dbvisit Replicate logs into the database as this schema owner and performs all operations in the source and target database under this credentials.
	It is strongly recommended to use a dedicated user for this, to make it possible to drop and recreate the whole configuration if needed.
DML	Data Manipulation Language. These are SQL statements that update or insert data into existing tables or objects.
	Example:
	INSERT INTO SCOTT.TEST VALUES (1, "TEST");
DDL	Data Definition Language. These are SQL statements that change the structure of the database. For example to create a new table or create a new user in the database.

Watch this explanatory video for an alternative overview of our Glossary of Terms: