Learn how to prepare your database for Oracle GoldenGate, including how to configure connections and logging, how to enable Oracle GoldenGate in your database, how to set the flashback query, and how to manage server resources.
Topics
tnsnames.ora
file.If you will be using integrated capture and integrated Replicat, each requires a dedicated server connection in the tnsnames.ora
file.
You direct the processes to use these connections with the USERID
or USERIDALIAS
parameter in the Extract and Replicat parameter files when you configure those processes.
The following is an example of the dedicated connection required for integrated capture (Extract) and integrated Replicat.
TEST = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = test2)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = test) ) )
The following are the security options for specifying the connection string in the Extract or Replicat parameter file.
Password encryption method:
USERID intext@test, PASSWORD mypassword
Credential store method:
USERIDALIAS ext
In the case of USERIDALIAS
, the alias ext
is stored in the Oracle GoldenGate credential store with the actual connection string, as in the following example:
GGSCI> INFO CREDENTIALSTORE DOMAIN support Domain: Support Alias: ext Userid: intext@test
For more information about specifying database connection information in the parameter file, see Administering Oracle GoldenGate.
Parent topic: Preparing the Database for Oracle GoldenGate
Oracle GoldenGate relies on the redo logs to capture the data that it needs to replicate source transactions. The Oracle redo logs on the source system must be configured properly before you start Oracle GoldenGate processing.
This section addresses the following logging levels that apply to Oracle GoldenGate. Which logging level that you use is dependent on the Oracle GoldenGate feature or features that you are using.
Note:
Redo volume is increased as the result of this required logging. You can wait until you are ready to start Oracle GoldenGate processing to enable the logging.
This table shows the Oracle GoldenGate use cases for the different logging properties.
Logging option | GGSCI command | What it does | Use case |
---|---|---|---|
Forced logging mode |
None; enable through the database. |
Forces the logging of all transactions and loads. |
Strongly recommended for all Oracle GoldenGate use cases. |
Minimum database-level supplemental logging |
None; enable through the database. |
Enables minimal supplemental logging to add row-chaining information to the redo log. |
Required for all Oracle GoldenGate use cases |
Schema-level supplemental logging, default setting |
|
Enables unconditional supplemental logging of the primary key and conditional supplemental logging of unique key(s) and foreign key(s) of all tables in a schema. All of these keys together are known as the scheduling columns. |
Enables the logging for all current and future tables in the schema. If the primary key, unique key, and foreign key columns are not identical at both source and target, use |
Schema-level supplemental logging with unconditional logging for all supported columns. (See Enabling Schema-level Supplemental Logging for non-supported column types.) |
|
Enables unconditional supplemental logging of all of the columns in a table, for all of the tables in a schema. |
Used for bidirectional and active-active configurations where all column values are checked, not just the changed columns, when attempting to perform an update or delete. This takes more resources though allows for the highest level of real-time data validation and thus conflict detection. It can also be used when the source and target primary, unique, and foreign keys are not the same or are constantly changing between source and target. |
Schema-level supplemental logging, minimal setting |
|
Enables unconditional supplemental logging of the primary key and all valid unique indexes of all tables in a schema. |
Use only for nonintegrated Replicat. This is the minimum required schema-level logging. |
Table-level supplemental logging with built-in support for integrated Replicat |
|
Enables unconditional supplemental logging of the primary key and conditional supplemental logging of unique key(s) and foreign key(s) of a table. All of these keys together are known as the scheduling columns. |
Required for all Oracle GoldenGate use cases unless schema-level supplemental logging is used. If the primary key, unique key, and foreign key columns are not identical at both source and target, use |
Table-level supplemental logging with unconditional logging for all supported columns. (See Enabling Table-level Supplemental Logging for non-supported column types.) |
|
Enables unconditional supplemental logging of all of the columns of the table. |
Used for bidirectional and active-active configurations where all column values are checked, not just the changed columns, when attempting to perform an update or delete. This takes more resources though allows for the highest level of real-time data validation and thus conflict detection. It can also be used when the source and target primary, unique, and foreign keys are not the same or are constantly changing between source and target. |
Table-level supplemental logging, minimal setting |
|
Enables unconditional supplemental logging of the primary key and all valid unique indexes of a table. |
Use only for nonintegrated Replicat. This is the minimum required table-level logging. |
Note:
Oracle Databases must be in ARCHIVELOG
mode so that Extract can process the log files.
Parent topic: Preparing the Database for Oracle GoldenGate
Oracle strongly recommends putting the Oracle source database into forced logging mode. Forced logging mode forces the logging of all transactions and loads, overriding any user or storage settings to the contrary. This ensures that no source data in the Extract configuration gets missed.
In addition, minimal supplemental logging, a database-level option, is required for an Oracle source database when using Oracle GoldenGate. This adds row chaining information, if any exists, to the redo log for update operations.
Note:
Database-level primary key (PK) and unique index (UI) logging is strongly discouraged because of the excessive additional overhead it creates on tables outside of replication. Unless those logging options are required for business purposes, you only need to enable minimal supplemental logging at the database level and force logging for Oracle GoldenGate.
Perform the following steps to verify and enable, if necessary, minimal supplemental logging and forced logging.
Parent topic: Configuring Logging Properties
Oracle GoldenGate supports schema-level supplemental logging. Schema-level logging is required for an Oracle source database when using the Oracle GoldenGate DDL replication feature. In all other use cases, it is optional, but then you must use table-level logging instead (see Enabling Table-level Supplemental Logging).
By default, schema-level logging automatically enables unconditional supplemental logging of the primary key and conditional supplemental logging of unique key(s) and foreign key(s) of all tables in a schema. Options enable you to alter the logging as needed.
Note:
Oracle strongly recommends using schema-level logging rather than table-level logging, because it ensures that any new tables added to a schema are captured if they satisfy wildcard specifications.
Perform the following steps on the source system to enable schema-level supplemental logging.
Parent topic: Configuring Logging Properties
Enable table-level supplemental logging on the source system in the following cases:
To enable the required level of logging when not using schema-level logging (see Enabling Schema-level Supplemental Logging). Either schema-level or table-level logging must be used. By default, table-level logging automatically enables unconditional supplemental logging of the primary key and conditional supplemental logging of unique key(s) and foreign key(s) of a table. Options enable you to alter the logging as needed.
To prevent the logging of the primary key for any given table.
To log non-key column values at the table level to support specific Oracle GoldenGate features, such as filtering and conflict detection and resolution logic.
Perform the following steps on the source system to enable table-level supplemental logging or use the optional features of the command.
Run GGSCI on the source system.
Issue the DBLOGIN
command using the alias of a user in the credential store who has privilege to enable table-level supplemental logging.
DBLOGIN USERIDALIAS alias
See USERIDALIAS in Reference for Oracle GoldenGatefor more information about DBLOGIN
and additional options.
Issue the ADD TRANDATA
command.
ADD TRANDATA [container.]schema.table [, COLS (columns)] [, NOKEY] [, ALLCOLS | NOSCHEDULINGCOLS]
Where:
container
is the name of the root container or pluggable database if the table is in a multitenant container database.
schema
is the source schema that contains the table.
table
is the name of the table. See Specifying Object Names in Oracle GoldenGate Input in Administering Oracle GoldenGate for instructions for specifying object names.
ADD TRANDATA
without other options automatically enables unconditional supplemental logging of the primary key and conditional supplemental logging of unique key(s) and foreign key(s) of the table. Unconditional logging forces the primary key values to the log whether or not the key was changed in the current operation. Conditional logging logs all of the column values of a foreign or unique key if at least one of them was changed in the current operation. The default is optional to support nonintegrated Replicat (see also NOSCHEDULINGCOLS
) but is required to support integrated Replicat because primary key, unique keys, and foreign keys must all be available to the inbound server to compute dependencies. For more information about integrated Replicat, see Deciding Which Apply Method to Use.
ALLCOLS
enables the unconditional supplemental logging of all of the columns of the table. Use to support integrated Replicat when the source and target tables have different scheduling columns. (Scheduling columns are the primary key, the unique key, and the foreign key.)
NOSCHEDULINGCOLS
is valid for Replicat in nonintegrated mode only. It issues an ALTER TABLE
command with an ADD SUPPLEMENTAL LOG DATA ALWAYS
clause that is appropriate for the type of unique constraint that is defined for the table, or all columns in the absence of a unique constraint. This command satisfies the basic table-level logging requirements of Oracle GoldenGate when schema-level logging will not be used. See Ensuring Row Uniqueness in Source and Target Tables for how Oracle GoldenGate selects a key or index.
COLS
columns
logs non-key columns that are required for a KEYCOLS
clause or for filtering and manipulation. The parentheses are required. These columns will be logged in addition to the primary key unless the NOKEY
option is also present.
NOKEY
prevents the logging of the primary key or unique key. Requires a KEYCOLS
clause in the TABLE
and MAP
parameters and a COLS
clause in the ADD TRANDATA
command to log the alternate KEYCOLS
columns.
If using ADD TRANDATA
with the COLS
option, create a unique index for those columns on the target to optimize row retrieval. If you are logging those columns as a substitute key for a KEYCOLS
clause, make a note to add the KEYCOLS
clause to the TABLE
and MAP
statements when you configure the Oracle GoldenGate processes.
Parent topic: Configuring Logging Properties
The database services required to support Oracle GoldenGate capture and apply must be enabled explicitly for an Oracle 11.2.0.4 or greater database.
The database services required to support Oracle GoldenGate capture and apply must be enabled explicitly for an Oracle 11.2.0.4 or greater database. This is required for all modes of Extract and Replicat.
To enable Oracle GoldenGate, set the following database initialization parameter. All instances in Oracle RAC must have the same setting.
ENABLE_GOLDENGATE_REPLICATION=true
For more information about this parameter, see Initialization Parameters.
Parent topic: Preparing the Database for Oracle GoldenGate
To process certain update records, Extract fetches additional row data from the source database.
Oracle GoldenGate fetches data for the following:
User-defined types
Nested tables
XMLType objects
By default, Oracle GoldenGate uses Flashback Query to fetch the values from the undo (rollback) tablespaces. That way, Oracle GoldenGate can reconstruct a read-consistent row image as of a specific time or SCN to match the redo record.
For best fetch results, configure the source database as follows:
Oracle GoldenGate provides the following parameters to manage fetching.
Parameter or Command | Description |
---|---|
|
Shows Extract fetch statistics on demand. |
|
Sets the |
|
Controls the number of open cursors for prepared queries that Extract maintains in the source database, and also for |
|
Controls the default fetch behavior of Extract: whether Extract performs a flashback query or fetches the current image from the table. |
|
Handles the failure of an Extract flashback query, such as if the undo retention expired or the structure of a table changed. Extract can fetch the current image from the table or ignore the failure. |
|
Controls the response by Replicat when it processes trail records that include fetched data or column-missing conditions. |
Parent topic: Preparing the Database for Oracle GoldenGate
In integrated mode, Extract interacts with an underlying logmining server in the source database and Replicat interacts with an inbound server in the target database. This section provides guidelines for managing the shared memory consumed by the these servers.
The shared memory that is used by the servers comes from the Streams pool portion of the System Global Area (SGA) in the database. Therefore, you must set the database initialization parameter STREAMS_POOL_SIZE
high enough to keep enough memory available for the number of Extract and Replicat processes that you expect to run in integrated mode. Note that Streams pool is also used by other components of the database (like Oracle Streams, Advanced Queuing, and Datapump export/import), so make certain to take them into account while sizing the Streams pool for Oracle GoldenGate.
By default, one integrated capture Extract requests the logmining server to run with MAX_SGA_SIZE
of 1GB. Thus, if you are running three Extracts in integrated capture mode in the same database instance, you need at least 3 GB of memory allocated to the Streams pool. As a best practice, keep 25 percent of the Streams pool available. For example, if there are 3 Extracts in integrated capture mode, set STREAMS_POOL_SIZE
for the database to the following value:
3 GB * 1.25 = 3.75 GB
Parent topic: Preparing the Database for Oracle GoldenGate