8 Adding to a Streams Replication Environment

Adding Shared Objects to an Existing Single-Source Environment

You add existing database objects to an existing single-source environment by adding the necessary rules to the appropriate capture processes, propagations, and apply processes. Before creating or altering capture or propagation rules in a running Streams environment, make sure any propagations or apply processes that will receive LCRs as a result of the new or altered rules are configured to handle these LCRs. That is, the propagations or apply processes should exist, and each one should be associated with rule sets that handle the LCRs appropriately. If these propagations and apply processes are not configured properly to handle these LCRs, then LCRs can be lost.

For example, suppose you want to add a table to a Streams environment that already captures, propagates, and applies changes to other tables. Assume only one capture process will capture changes to this table, and only one apply process will apply changes to this table. In this case, you must add one or more table rules to the following rule sets:

• The positive rule set for the apply process that will apply changes to the table

• The positive rule set for each propagation that will propagate changes to the table

• The positive rule set for the capture process that will capture changes to the table

If you perform administrative steps in the wrong order, you can lose LCRs. For example, if you add the rule to a capture process rule set first, without stopping the capture process, then the propagation will not propagate the changes if it does not have a rule that instructs it to do so, and the changes can be lost.

This example assumes that the shared database objects are read-only at the destination databases. If the shared objects are read/write at the destination databases, then the replication environment will not stay synchronized because Streams is not configured to replicate the changes made to the shared objects at the destination databases.

Figure 8-1 shows the additional configuration steps that must be completed to add shared database objects to a single-source Streams environment.

To avoid losing LCRs, you should complete the configuration in the following order:

1. At each source database where shared objects are being added, specify supplemental logging for the added shared objects. See "Managing Supplemental Logging in a Streams Replication Environment" for instructions.

2. Either stop the capture process, one of the propagations, or the apply processes:

   • Use the STOP_CAPTURE procedure in the DBMS_CAPTURE_ADM package to stop a capture process.

   • Use the STOP_PROPAGATION procedure in the DBMS_PROPAGATION_ADM package to stop a propagation.

   • Use the STOP_APPLY procedure in the DBMS_APPLY_ADM package to stop an apply process.

     
     

     See Also: Oracle Streams Concepts and Administration for more information about completing these tasks

     
     

3. Add the relevant rules to the rule sets for the apply processes. To add rules to the rule set for an apply process, you can run one of the following procedures:

   • DBMS_STREAMS_ADM.ADD_TABLE_RULES

   • DBMS_STREAMS_ADM.ADD_SUBSET_RULES

   • DBMS_STREAMS_ADM.ADD_SCHEMA_RULES

   • DBMS_STREAMS_ADM.ADD_GLOBAL_RULES

   Excluding the ADD_SUBSET_RULES procedure, these procedures can add rules to the positive or negative rule set for an apply process. The ADD_SUBSET_RULES procedure can add rules only to the positive rule set for an apply process.

4. Add the relevant rules to the rule sets for the propagations. To add rules to the rule set for a propagation, you can run one of the following procedures:

   • DBMS_STREAMS_ADM.ADD_TABLE_PROPAGATION_RULES

   • DBMS_STREAMS_ADM.ADD_SUBSET_PROPAGATION_RULES

   • DBMS_STREAMS_ADM.ADD_SCHEMA_PROPAGATION_RULES

   • DBMS_STREAMS_ADM.ADD_GLOBAL_PROPAGATION_RULES

   Excluding the ADD_SUBSET_PROPAGATION_RULES procedure, these procedures can add rules to the positive or negative rule set for a propagation. The ADD_SUBSET_PROPAGATION_RULES procedure can add rules only to the positive rule set for a propagation.

5. Add the relevant rules to the rule sets used by the capture process. To add rules to a rule set for an existing capture process, you can run one of the following procedures and specify the existing capture process:

   • DBMS_STREAMS_ADM.ADD_TABLE_RULES

   • DBMS_STREAMS_ADM.ADD_SUBSET_RULES

   • DBMS_STREAMS_ADM.ADD_SCHEMA_RULES

   • DBMS_STREAMS_ADM.ADD_GLOBAL_RULES

   Excluding the ADD_SUBSET_RULES procedure, these procedures can add rules to the positive or negative rule set for a capture process. The ADD_SUBSET_RULES procedure can add rules only to the positive rule set for a capture process.

   When you a procedure in the DBMS_STREAMS_ADM package to add the capture process rules, it automatically runs the PREPARE_TABLE_INSTANTIATION, PREPARE_SCHEMA_INSTANTIATION, or PREPARE_GLOBAL_INSTANTIATION procedure in the DBMS_CAPTURE_ADM package for the specified table, specified schema, or entire database, respectively, if the capture process is a local capture process or a downstream capture process with a database link to the source database.

   You must run the appropriate procedure to prepare for instantiation manually if any of the following conditions is true:

   • You use DBMS_RULE_ADM to create or modify rules in a capture process rule set.

   • You do not add rules for the added objects to a capture process rule set, because the capture process already captures changes to these objects. In this case, rules for the objects can be added to propagations and apply processes in the environment, but not to the capture process.

   • You use a downstream capture process with no database link to the source database.

   If you must prepare for instantiation manually, then see "Preparing Database Objects for Instantiation at a Source Database" for instructions.

6. At each destination database, either instantiate, or set the instantiation SCN for, each database object you are adding to the Streams environment. If the database objects do not exist at a destination database, then instantiate them using export/import, transportable tablespaces, or RMAN. If the database objects already exist at a destination database, then set the instantiation SCNs for them manually.

   • To instantiate database objects using export/import, first export them at the source database. Next, import them at the destination database. See "Setting Instantiation SCNs Using Export/Import" for information. Also, see "Instantiating Objects in a Streams Replication Environment" for information about instantiating objects using export/import, transportable tablespaces, and RMAN.

     If you use the original Export utility, then set the OBJECT_CONSISTENT export parameter to y. Regardless of whether you use Data Pump export or original export, you can specify a more stringent degree of consistency by using an export parameter such as FLASHBACK_SCN or FLASHBACK_TIME.

     If you use the original Import utility, then set the STREAMS_INSTANTIATION import parameter to y.

   • To set the instantiation SCN for a table, schema, or database manually, run the appropriate procedure or procedures in the DBMS_APPLY_ADM package at a destination database:

     • SET_TABLE_INSTANTIATION_SCN

     • SET_SCHEMA_INSTANTIATION_SCN

     • SET_GLOBAL_INSTANTIATION_SCN

     When you run one of these procedures at a destination database, you must ensure that every added object at the destination database is consistent with the source database as of the instantiation SCN.

     If you run SET_GLOBAL_INSTANTIATION_SCN at a destination database, then set the recursive parameter for this procedure to true so that the instantiation SCN also is set for each schema at the destination database and for the tables owned by these schemas.

     If you run SET_SCHEMA_INSTANTIATION_SCN at a destination database, then set the recursive parameter for this procedure to true so that the instantiation SCN also is set for each table in the schema.

     If you set the recursive parameter to true in the SET_GLOBAL_INSTANTIATION_SCN procedure or the SET_SCHEMA_INSTANTIATION_SCN procedure, then a database link from the destination database to the source database is required. This database link must have the same name as the global name of the source database and must be accessible to the user who executes the procedure. See "Setting Instantiation SCNs Using the DBMS_APPLY_ADM Package" for instructions.

     Alternatively, you can perform a metadata export/import to set the instantiation SCNs for existing database objects. If you choose this option, then make sure no rows are imported. Also, make sure every added object at the importing destination database is consistent with the source database that performed the export at the time of the export. If you are sharing DML changes only, then table level export/import is sufficient. If you are sharing DDL changes also, then additional considerations apply. See "Setting Instantiation SCNs Using Export/Import" for more information about performing a metadata export/import.

7. Start any Streams client you stopped in Step 2:

   • Use the START_CAPTURE procedure in the DBMS_CAPTURE_ADM package to start a capture process.

   • Use the START_PROPAGATION procedure in the DBMS_PROPAGATION_ADM package start a propagation.

   • Use the START_APPLY procedure in the DBMS_APPLY_ADM package to start an apply process.

     
     

     See Also: Oracle Streams Concepts and Administration for more information about completing these tasks

     
     

You must stop the capture process, disable one of the propagation jobs, or stop the apply process in Step 2 to ensure that the table or schema is instantiated before the first LCR resulting from the added rule(s) reaches the apply process. Otherwise, LCRs could be lost or could result in apply errors, depending on whether the apply process rule(s) have been added.

If you are certain that the added table is not being modified at the source database during this procedure, and that there are no LCRs for the table already in the stream or waiting to be captured, then you can perform Step 7 before Step 6 to reduce the amount of time that a Streams process or propagation job is stopped.

Adding a New Destination Database to a Single-Source Environment

You add a destination database to an existing single-source environment by creating one or more new apply processes at the new destination database and, if necessary, configuring one or more propagations to propagate changes to the new destination database. You might also need to add rules to existing propagations in the stream that propagates to the new destination database.

As in the example that describes "Adding Shared Objects to an Existing Single-Source Environment", before creating or altering propagation rules in a running Streams environment, make sure any propagations or apply processes that will receive LCRs as a result of the new or altered rules are configured to handle these LCRs. Otherwise, LCRs can be lost.

This example assumes that the shared database objects are read-only at the destination databases. If the shared objects are read/write at the destination databases, then the replication environment will not stay synchronized because Streams is not configured to replicate the changes made to the shared objects at the destination databases.

Figure 8-2 shows the additional configuration steps that must be completed to add a destination database to a single-source Streams environment.

To avoid losing LCRs, you should complete the configuration in the following order:

1. Complete the necessary tasks to prepare each database in your environment for Streams:

   • Configure a Streams administrator

   • Set initialization parameters relevant to Streams

   • Configure network connectivity and database links

   Some of these tasks might not be required at certain databases.

   
   

   See Also: Oracle Streams Concepts and Administration for more information about preparing a database for Streams

   
   

2. Create any necessary ANYDATA queues that do not already exist at the destination database. When you create an apply process, you associate the apply process with a specific ANYDATA queue. See "Creating an ANYDATA Queue to Stage LCRs" for instructions.

3. Create one or more apply processes at the new destination database to apply the changes from its source database. Make sure each apply process uses rule sets that are appropriate for applying changes. Do not start any of the apply processes at the new database. See "Creating an Apply Process that Applies LCRs" for instructions.

   Keeping the apply processes stopped prevents changes made at the source databases from being applied before the instantiation of the new database is completed, which would otherwise lead to incorrect data and errors.

4. Configure any necessary propagations to propagate changes from the source databases to the new destination database. Make sure each propagation uses rule sets that are appropriate for propagating changes. See "Creating a Propagation that Propagates LCRs".

5. At the source database, prepare for instantiation each database object for which changes will be applied by an apply process at the new destination database. Run either the PREPARE_TABLE_INSTANTIATION, PREPARE_SCHEMA_INSTANTIATION, or PREPARE_GLOBAL_INSTANTIATION procedure in the DBMS_CAPTURE_ADM package for the specified table, specified schema, or entire database, respectively. See "Preparing Database Objects for Instantiation at a Source Database" for instructions.

6. At the new destination database, either instantiate, or set the instantiation SCNs for, each database object for which changes will be applied by an apply process. If the database objects do not already exist at the new destination database, then instantiate them using export/import, transportable tablespaces, or RMAN. If the database objects exist at the new destination database, then set the instantiation SCNs for them.

   • To instantiate database objects using export/import, first export them at the source database. Next, import them at the destination database. See "Setting Instantiation SCNs Using Export/Import" for information. Also, see "Instantiating Objects in a Streams Replication Environment" for information about instantiating objects using export/import, transportable tablespaces, and RMAN.

     If you use the original Export utility, then set the OBJECT_CONSISTENT export parameter to y. Regardless of whether you use Data Pump export or original export, you can specify a more stringent degree of consistency by using an export parameter such as FLASHBACK_SCN or FLASHBACK_TIME.

     If you use the original Import utility, then set the STREAMS_INSTANTIATION import parameter to y.

   • To set the instantiation SCN for a table, schema, or database manually, run the appropriate procedure or procedures in the DBMS_APPLY_ADM package at the new destination database:

     • SET_TABLE_INSTANTIATION_SCN

     • SET_SCHEMA_INSTANTIATION_SCN

     • SET_GLOBAL_INSTANTIATION_SCN

     When you run one of these procedures, you must ensure that the shared objects at the new destination database are consistent with the source database as of the instantiation SCN.

     If you run SET_GLOBAL_INSTANTIATION_SCN at a destination database, then set the recursive parameter for this procedure to true so that the instantiation SCN also is set for each schema at the destination database and for the tables owned by these schemas.

     If you run SET_SCHEMA_INSTANTIATION_SCN at a destination database, then set the recursive parameter for this procedure to true so that the instantiation SCN also is set for each table in the schema.

     If you set the recursive parameter to true in the SET_GLOBAL_INSTANTIATION_SCN procedure or the SET_SCHEMA_INSTANTIATION_SCN procedure, then a database link from the destination database to the source database is required. This database link must have the same name as the global name of the source database and must be accessible to the user who executes the procedure. See "Setting Instantiation SCNs Using the DBMS_APPLY_ADM Package" for instructions.

     Alternatively, you can perform a metadata export/import to set the instantiation SCNs for existing database objects. If you choose this option, then make sure no rows are imported. Also, make sure the shared objects at the importing destination database are consistent with the source database that performed the export at the time of the export. If you are sharing DML changes only, then table level export/import is sufficient. If you are sharing DDL changes also, then additional considerations apply. See "Setting Instantiation SCNs Using Export/Import" for more information about performing a metadata export/import.

7. Start the apply processes you created in Step 3 using the START_APPLY procedure in the DBMS_APPLY_ADM package.

   
   

   See Also: "Add a Database to an Existing Streams Replication Environment" for detailed example that adds a database to an existing single-source environment

   
   

Adding Shared Objects to an Existing Multiple-Source Environment

You add existing database objects to an existing multiple-source environment by adding the necessary rules to the appropriate capture processes, propagations, and apply processes.

This example uses the following terms:

• Populated database: A database that already contains the shared database objects being added to the multiple-source environment. You must have at least one populated database to add the objects to the environment.

• Export database: A populated database on which you perform an export of the database objects you are adding to the environment. This export is used to instantiate the added database objects at the import databases. You might not have an export database if all of the databases in the environment are populated databases.

• Import database: A database that does not contain the shared database objects before they are added to the multiple-source environment. You instantiate the shared database objects at an import database by performing an import of these database objects. You might not have any import databases if all of the databases in the environment are populated databases.

Before creating or altering capture or propagation rules in a running Streams environment, make sure any propagations or apply processes that will receive LCRs as a result of the new or altered rules are configured to handle these LCRs. That is, the propagations or apply processes should exist, and each one should be associated with rule sets that handle the LCRs appropriately. If these propagations and apply processes are not configured properly to handle these LCRs, then LCRs can be lost.

For example, suppose you want to add a new table to a Streams environment that already captures, propagates, and applies changes to other tables. Assume multiple capture processes in the environment will capture changes to this table, and multiple apply processes will apply changes to this table. In this case, you must add one or more table rules to the following rule sets:

• The positive rule set for each apply process that will apply changes to the table.

• The positive rule set for each propagation that will propagate changes to the table

• The positive rule set for each capture process that will capture changes to the table

If you perform administrative steps in the wrong order, you can lose LCRs. For example, if you add the rule to a capture process rule set first, without stopping the capture process, then the propagation will not propagate the changes if it does not have a rule that instructs it to do so, and the changes can be lost.

Figure 8-3 shows the additional configuration steps that must be completed to add shared database objects to a multiple-source Streams environment.

To avoid losing LCRs, you should complete the configuration in the following order:

1. At each populated database, specify any necessary supplemental logging for the objects being added to the environment. See "Managing Supplemental Logging in a Streams Replication Environment" for instructions.

2. Either stop all of the capture processes that will capture changes to the added objects, stop all of the propagations that will propagate changes to the added objects, or stop all of the apply process that will apply changes to the added objects:

   • Use the STOP_CAPTURE procedure in the DBMS_CAPTURE_ADM package to stop a capture process.

   • Use the STOP_PROPAGATION procedure in the DBMS_PROPAGATION_ADM package to stop a propagation.

   • Use the STOP_APPLY procedure in the DBMS_APPLY_ADM package to stop an apply process.

     
     

     See Also: Oracle Streams Concepts and Administration for more information about completing these tasks

     
     

3. Add the relevant rules to the rule sets for the apply processes that will apply changes to the added objects. To add rules to the rule set for an apply process, you can run one of the following procedures:

   • DBMS_STREAMS_ADM.ADD_TABLE_RULES

   • DBMS_STREAMS_ADM.ADD_SUBSET_RULES

   • DBMS_STREAMS_ADM.ADD_SCHEMA_RULES

   • DBMS_STREAMS_ADM.ADD_GLOBAL_RULES

   Excluding the ADD_SUBSET_RULES procedure, these procedures can add rules to the positive or negative rule set for an apply process. The ADD_SUBSET_RULES procedure can add rules only to the positive rule set for an apply process.

4. Add the relevant rules to the rule sets for the propagations that will propagate changes to the added objects. To add rules to the rule set for a propagation, you can run one of the following procedures:

   • DBMS_STREAMS_ADM.ADD_TABLE_PROPAGATION_RULES

   • DBMS_STREAMS_ADM.ADD_SUBSET_PROPAGATION_RULES

   • DBMS_STREAMS_ADM.ADD_SCHEMA_PROPAGATION_RULES

   • DBMS_STREAMS_ADM.ADD_GLOBAL_PROPAGATION_RULES

   Excluding the ADD_SUBSET_PROPAGATION_RULES procedure, these procedures can add rules to the positive or negative rule set for a propagation. The ADD_SUBSET_PROPAGATION_RULES procedure can add rules only to the positive rule set for a propagation.

5. Add the relevant rules to the rule sets used by each capture process that will capture changes to the added objects. To add rules to a rule set for an existing capture process, you can run one of the following procedures and specify the existing capture process:

   • DBMS_STREAMS_ADM.ADD_TABLE_RULES

   • DBMS_STREAMS_ADM.ADD_SUBSET_RULES

   • DBMS_STREAMS_ADM.ADD_SCHEMA_RULES

   • DBMS_STREAMS_ADM.ADD_GLOBAL_RULES

   Excluding the ADD_SUBSET_RULES procedure, these procedures can add rules to the positive or negative rule set for a capture process. The ADD_SUBSET_RULES procedure can add rules only to the positive rule set for a capture process.

   When you a procedure in the DBMS_STREAMS_ADM package to add the capture process rules, it automatically runs the PREPARE_TABLE_INSTANTIATION, PREPARE_SCHEMA_INSTANTIATION, or PREPARE_GLOBAL_INSTANTIATION procedure in the DBMS_CAPTURE_ADM package for the specified table, specified schema, or entire database, respectively, if the capture process is a local capture process or a downstream capture process with a database link to the source database.

   You must run the appropriate procedure to prepare for instantiation manually if any of the following conditions is true:

   • You use DBMS_RULE_ADM to create or modify rules in a capture process rule set.

   • You do not add rules for the added objects to a capture process rule set, because the capture process already captures changes to these objects. In this case, rules for the objects can be added to propagations and apply processes in the environment, but not to the capture process.

   • You use a downstream capture process with no database link to the source database.

   If you must prepare for instantiation manually, then see "Preparing Database Objects for Instantiation at a Source Database" for instructions.

After completing these steps, complete the steps in each of the following sections that apply to your environment. You might need to complete the steps in only one of these sections or in both of these sections:

• For each populated database, complete the steps in "Configuring Populated Databases When Adding Shared Objects". These steps are required only if your environment has more than one populated database.

• For each import database, complete the steps in "Adding Shared Objects to Import Databases in an Existing Environment".

Adding a New Database to an Existing Multiple-Source Environment

Figure 8-4 shows the additional configuration steps that must be completed to add a source/destination database to a multiple-source Streams environment.

Complete the following steps to add a new source/destination database to an existing multiple-source Streams environment:

1. Complete the necessary tasks to prepare each database in your environment for Streams:

   • Configure a Streams administrator

   • Set initialization parameters relevant to Streams

   • For each database that will run a capture process, prepare the database to run a capture process

   • Configure network connectivity and database links

   Some of these tasks might not be required at certain databases.

   
   

   See Also: Oracle Streams Concepts and Administration for more information about preparing a database for Streams

   
   

2. Create any necessary ANYDATA queues that do not already exist. When you create a capture process or apply process, you associate the process with a specific ANYDATA queue. When you create a propagation, you associate it with a specific source queue and destination queue. See "Creating an ANYDATA Queue to Stage LCRs" for instructions.

3. Create one or more apply processes at the new database to apply the changes from its source databases. Make sure each apply process uses rule sets that are appropriate for applying changes. Do not start any apply process at the new database. See "Creating an Apply Process that Applies LCRs" for instructions.

   Keeping the apply processes stopped prevents changes made at the source databases from being applied before the instantiation of the new database is completed, which would otherwise lead to incorrect data and errors.

4. If the new database will be a source database, then, at all databases that will be destination databases for the changes made at the new database, create one or more apply processes to apply changes from the new database. Make sure each apply process uses rule sets that are appropriate for applying changes. Do not start any of these new apply processes. See "Creating an Apply Process that Applies LCRs" for instructions.

5. Configure propagations at the databases that will be source databases of the new database to send changes to the new database. Make sure each propagation uses rule sets that are appropriate for propagating changes. See "Creating a Propagation that Propagates LCRs".

6. If the new database will be a source database, then configure propagations at the new database to send changes from the new database to each of its destination databases. Make sure each propagation uses rule sets that are appropriate for propagating changes. See "Creating a Propagation that Propagates LCRs".

7. If the new database will be a source database, and the shared objects already exist at the new database, then specify any necessary supplemental logging for the shared objects at the new database. See "Managing Supplemental Logging in a Streams Replication Environment" for instructions.

8. At each source database for the new database, prepare for instantiation each database object for which changes will be applied by an apply process at the new database. Run either the PREPARE_TABLE_INSTANTIATION, PREPARE_SCHEMA_INSTANTIATION, or PREPARE_GLOBAL_INSTANTIATION procedure in the DBMS_CAPTURE_ADM package for the specified table, specified schema, or entire database, respectively. See "Preparing Database Objects for Instantiation at a Source Database" for instructions.

9. If the new database will be a source database, then create one or more capture processes to capture the relevant changes. See "Creating a Capture Process" for instructions. Oracle recommends that you use only one capture process for each source database.

   When you use a procedure in the DBMS_STREAMS_ADM package to add the capture process rules, it automatically runs the PREPARE_TABLE_INSTANTIATION, PREPARE_SCHEMA_INSTANTIATION, or PREPARE_GLOBAL_INSTANTIATION procedure in the DBMS_CAPTURE_ADM package for the specified table, specified schema, or entire database, respectively, if the capture process is a local capture process or a downstream capture process with a database link to the source database.

   You must run the appropriate procedure to prepare for instantiation manually if any of the following conditions is true:

   • You use the DBMS_RULE_ADM package to add or modify rules.

   • You use an existing capture process and do not add capture process rules for any shared object.

   • You use a downstream capture process with no database link to the source database.

   If you must prepare for instantiation manually, then see "Preparing Database Objects for Instantiation at a Source Database" for instructions.

10. If the new database will be a source database, then start any capture process you created in Step 9 using the START_CAPTURE procedure in the DBMS_CAPTURE_ADM package.

After completing these steps, complete the steps in the appropriate section:

• If the objects that are to be shared with the new database already exist at the new database, then complete the steps in "Configuring Databases If the Shared Objects Already Exist at the New Database".

• If the objects that are to be shared with the new database do not already exist at the new database, complete the steps in "Adding Shared Objects to a New Database".