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Glossary of Terms

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

TermDescription
Source databaseThe 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 databaseThe 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 processThe 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 processThe 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 ConsoleAll 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 processFETCHER 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.
PLOGMINE 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.
The PLOGs are transferred to the target server where they are used by the APPLY process.
Source ServerThe host or server that runs the source database. Dbvisit Replicate will be installed on this server.
Target ServerThe host or server that runs the target database. Dbvisit Replicate will be installed on this server.
Install directoryThe directory where Dbvisit Replicate will be installed.
ORACLE_HOMEThe directory where the Oracle software or executables are installed.
TNS_ADMINThe directory where the Oracle network configuration files are located (sqlnet.ora, tnsnames.ora)
Oracle software ownerThis 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 keyEvery 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.
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 schemaA 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.
DMLData Manipulation Language. These are SQL statements that update or insert data into existing tables or objects.
Example:
INSERT INTO SCOTT.TEST VALUES (1, "TEST");
DDLData 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.
Event StreamingEvent Streaming also known as CDC/Audit. The Replicate MINE engine gathers the required data as normal and the Replicate APPLY engine turns all DML statement into inserts. Along with metadata surrounding these transactions this data is applied to a staging table where it is typically picked up by an ETL tool to be loaded into a data warehouse.

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

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