Oracle® Streams Concepts and Administration 10g Release 1 (10.1) Part Number B10727-01 |
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A capture process captures changes in a redo log, reformats the captured changes into logical change records (LCRs), and enqueues the LCRs into a SYS.AnyData
queue.
This chapter contains these topics:
Each task described in this chapter should be completed by a Streams administrator that has been granted the appropriate privileges, unless specified otherwise.
You can create a capture process that captures changes to the local source database, or you can create a capture process that captures changes remotely at a downstream database. If a capture process runs on a downstream database, then redo log files from the source database are copied to the downstream database, and the capture process captures changes in these redo log files at the downstream database.
You can use any of the following procedures to create a local 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
DBMS_CAPTURE_ADM.CREATE_CAPTURE
Each of the procedures in the DBMS_STREAMS_ADM
package creates a capture process with the specified name if it does not already exist, creates either a positive or negative rule set for the capture process if the capture process does not have such a rule set, and may add table, schema, or global rules to the rule set.
The CREATE_CAPTURE
procedure creates a capture process, but does not create a rule set or rules for the capture process. However, the CREATE_CAPTURE
procedure enables you to specify an existing rule set to associate with the capture process, either as a positive or a negative rule set, a first SCN, and a start SCN for the capture process. To create a capture process that performs downstream capture, you must use the CREATE_CAPTURE
procedure.
Attention: When a capture process is started or restarted, it may need to scan redo log files with a |
The following tasks must be completed before you create a capture process:
SYS.AnyData
queue to associate with the capture process, if one does not exist. See "Creating a SYS.AnyData Queue" for instructions.The following sections describe:
See Also:
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The following sections describe using the DBMS_STREAMS_ADM
package and the DBMS_CAPTURE_ADM
package to create a local capture process.
The following is an example that runs the ADD_TABLE_RULES
procedure in the DBMS_STREAMS_ADM
package to create a local capture process:
BEGIN DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name => 'hr.employees', streams_type => 'capture', streams_name => 'strm01_capture', queue_name => 'strm01_queue', include_dml => true, include_ddl => true, include_tagged_lcr => false, source_database => NULL, inclusion_rule => true); END; /
Running this procedure performs the following actions:
strm01_capture
. The capture process is created only if it does not already exist. If a new capture process is created, then this procedure also sets the start SCN to the point in time of creation.strm01_queue
inclusion_rule
parameter is set to true
. The rule set uses the SYS.STREAMS$_EVALUATION_CONTEXT
evaluation context. The rule set name is specified by the system.TRUE
for DML changes to the hr.employees
table, and the other rule evaluates to TRUE
for DDL changes to the hr.employees
table. The rule names are specified by the system.inclusion_rule
parameter is set to true
.NULL
tag, because the include_tagged_lcr
parameter is set to false
. This behavior is accomplished through the system-created rules for the capture process.source_database
parameter is set to NULL
. For a local capture process, you also may specify the global name of the local database for this parameter.hr.employees
table for instantiation
See Also:
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The following is an example that runs the CREATE_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to create a local capture process:
BEGIN DBMS_CAPTURE_ADM.CREATE_CAPTURE( queue_name => 'strm02_queue', capture_name => 'strm02_capture', rule_set_name => 'strmadmin.strm01_rule_set', start_scn => NULL, source_database => NULL, use_database_link => false, first_scn => NULL); END; /
Running this procedure performs the following actions:
strm02_capture
. A capture process with the same name must not exist.strm02_queue
strm01_rule_set
. This rule set is the positive rule set for the capture process.source_database
parameter is set to NULL
. For a local capture process, you also may specify the global name of the local database for this parameter.start_scn
parameter and the first_scn
parameter are set to NULL
.BUILD
procedure in the DBMS_CAPTURE_ADM
package is run automatically. Running this procedure extracts the data dictionary to the redo log, and a LogMiner data dictionary is created when the capture process is started for the first time.
To create a capture process that performs downstream capture, you must use the CREATE_CAPTURE
procedure. The following sections describe creating a downstream capture process that uses a database link to the source database and one that does not. In both examples, assume the following:
dbs1.net
and the downstream database is dbs2.net
.dbs2.net
uses the strm03_queue
.hr.departments
table.Whether a database link from the downstream database to the source database is used or not, complete the following steps to prepare the source database to copy its redo log files to the downstream database, and to prepare the downstream database to accept these redo log files.
LOG_ARCHIVE_DEST_
n
initialization parameter to a directory on the computer system running the downstream database. To do this, set the following attributes of this parameter:
SERVICE
- Specify the network service name of the downstream database.ARCH
or LGWR
ASYNC
- If you specify ARCH
(the default), then the archiver process (ARC
n
) will archive the redo log files to the downstream database. If you specify LGWR
ASYNC
, then the log writer process (LGWR
) will archive the redo log files to the downstream database. Either ARCH
or LGWR
ASYNC
is acceptable for a downstream database destination.MANDATORY
or OPTIONAL
- If you specify MANDATORY
, then archiving of a redo log file to the downstream database must succeed before the corresponding online redo log at the source database can be overwritten. If you specify OPTIONAL
, then successful archiving of a redo log file to the downstream database is not required before the corresponding online redo log at the source database can be overwritten. Either MANDATORY
or OPTIONAL
is acceptable for a downstream database destination.NOREGISTER
- Specify this attribute so that the downstream database location is not recorded in the downstream database control file.REOPEN
- Specify the minimum number of seconds the archiver process (ARC
n
) should wait before trying to access the downstream database location if a previous attempt to access this location failed.TEMPLATE
- Specify a directory and format template for archived redo logs at the downstream database. The TEMPLATE
attribute overrides the LOG_ARCHIVE_FORMAT
initialization parameter settings at the downstream database. The TEMPLATE
attribute is valid only with remote destinations. Make sure the format uses all of the following variables at each source database: %t
, %s
, and %r
.The following is an example of an LOG_ARCHIVE_DEST_
n
setting that specifies a downstream database:
LOG_ARCHIVE_DEST_2='SERVICE=DBS2.NET ARCH OPTIONAL NOREGISTER REOPEN=60 TEMPLATE=/usr/oracle/log_for_dbs1/dbs1_arch_%t_%s_%r.log'
If another source database transfers log files to this downstream database, then, in the initialization parameter file at this other source database, you can use the TEMPLATE
attribute to specify a different directory and format for the log files at the downstream database. The log files from each source database are kept separate at the downstream database.
LOG_ARCHIVE_DEST_STATE_
n
initialization parameter that corresponds with the LOG_ARCHIVE_DEST_
n
parameter for the downstream database to enable
.
For example, if the LOG_ARCHIVE_DEST_2
initialization parameter is set for the downstream database, then set one LOG_ARCHIVE_DEST_STATE_2
parameter in the following way:
LOG_ARCHIVE_DEST_STATE_2=enable
REMOTE_ARCHIVE_ENABLE
initialization parameter to true
.
See Also:
Oracle Database Reference and Oracle Data Guard Concepts and Administration for more information about these initialization parameters |
If you did not reset the initialization parameters while the instance was running, but instead reset them in the initialization parameter file in Step 2, then restart the database. The source database must be open when it sends redo log files to the downstream database because the global name of the source database is sent to the downstream database only if the source database is open.
hr.departments
table at the source database dbs1.net
:
ALTER TABLE hr.departments ADD SUPPLEMENTAL LOG DATA (PRIMARY KEY) COLUMNS;
Primary key supplemental logging is required for the hr.departments
table because the examples in this section create capture processes that capture changes to this table.
This section contains an example that runs the CREATE_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to create a capture process at the dbs2.net
downstream database that captures changes made to the dbs1.net
source database. The capture process in this example uses a database link to dbs1.net
for administrative purposes.
Connect to the downstream database dbs2.net
as the Streams administrator and complete the following steps:
dbs2.net
to dbs1.net
. For example, if the user strmadmin
is the Streams administrator on both databases, then create the following database link:
CONNECT strmadmin/strmadminpw@dbs2.net CREATE DATABASE LINK dbs1.net CONNECT TO strmadmin IDENTIFIED BY strmadminpw USING 'dbs1.net';
This example assumes that a Streams administrator exists at the source database dbs1.net
. If no Streams administrator exists at the source database, then the Streams administrator at the downstream database should connect to a user who allows remote access by a Streams administrator. You can enable remote access for a user by specifying the user as the grantee when you run the GRANT_REMOTE_ADMIN_ACCESS
procedure in the DBMS_STREAMS_AUTH
package at the source database.
BEGIN DBMS_STREAMS_ADM.SET_UP_QUEUE( queue_table => 'strmadmin.strm03_queue_table', queue_name => 'strmadmin.strm03_queue'); END; /
CREATE_CAPTURE
procedure to create the capture process:
BEGIN DBMS_CAPTURE_ADM.CREATE_CAPTURE( queue_name => 'strm03_queue', capture_name => 'strm03_capture', rule_set_name => NULL, start_scn => NULL, source_database => 'dbs1.net', use_database_link => true, first_scn => NULL, logfile_assignment => 'implicit'); END; /
Running this procedure performs the following actions:
strm03_capture
at the downstream database dbs2.net
. A capture process with the same name must not exist.dbs2.net
named strm03_queue
dbs1.net
dbs1.net
. Therefore, the capture process scans any new log files copied from dbs1.net
to dbs2.net
for changes that it must capture. These log files can be added to the capture process automatically using log transport services or manually using the following DDL statement:
ALTER DATABASE REGISTER LOGICAL LOGFILE file_name FOR capture_process;
Here, file_name
is the name of the redo log file and capture_process
is the name of the capture process that will use the redo log file at the downstream database. You must add redo log files manually only if the logfile_assignment
parameter is set to explicit
.
This step does not associate the capture process strm03_capture
with any rule set. A rule set will be created and associated with the capture process in the next step.
If no other capture process at dbs2.net
is capturing changes from the dbs1.net
source database, then the DBMS_CAPTURE_ADM.BUILD
procedure is run automatically at dbs1.net
using the database link. Running this procedure extracts the data dictionary at dbs1.net
to the redo log, and a LogMiner data dictionary for dbs1.net
is created at dbs2.net
when the capture process strm03_capture
is started for the first time at dbs2.net
.
If multiple capture processes at dbs2.net
are capturing changes from the dbs1.net
source database, then the new capture process strm03_capture
uses the same LogMiner data dictionary for dbs1.net
as one of the existing capture process. Streams automatically chooses which LogMiner data dictionary to share with the new capture process.
See Also:
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BEGIN DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name => 'hr.departments', streams_type => 'capture', streams_name => 'strm03_capture', queue_name => 'strm03_queue', include_dml => true, include_ddl => false, include_tagged_lcr => false, source_database => 'dbs1.net', inclusion_rule => true); END; /
Running this procedure performs the following actions:
dbs2.net
for capture process strm03_capture
. The rule set has a system-generated name. The rule set is the positive rule set for the capture process because the inclusion_rule
parameter is set to true
.hr.departments
table, and adds the rule to the positive rule set for the capture process. The rule has a system-generated name. The rule is added to the positive rule set for the capture process because the inclusion_rule
parameter is set to true
.hr.departments
table at dbs1.net
for instantiation using the database link created in Step 1Now you can configure propagation or apply, or both, of the LCRs captured by the strm03_capture
capture process.
In this example, if you want to use an apply process to apply the LCRs at the downstream database dbs2.net
, then set the instantiation SCN for the hr.departments
table at dbs2.net
. If this table does not exist at dbs2.net
, then instantiate it at dbs2.net
.
For example, if the hr.departments
table exists at dbs2.net
, then set the instantiation SCN for the hr.departments
table at dbs2.net
by running the following procedure at the destination database dbs2.net
:
DECLARE iscn NUMBER; -- Variable to hold instantiation SCN value BEGIN iscn := DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER@DBS1.NET; DBMS_APPLY_ADM.SET_TABLE_INSTANTIATION_SCN( source_object_name => 'hr.departments', source_database_name => 'dbs1.net', instantiation_scn => iscn); END; /
After the instantiation SCN has been set, you can configure an apply process to apply LCRs for the hr.departments
table from the strm03_queue
queue. Setting the instantiation SCN for an object at a database is required only if an apply process applies LCRs for the object.
See Also:
Oracle Streams Replication Administrator's Guide for more information about instantiation |
This section contains an example that runs the CREATE_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to create a capture process at the dbs2.net
downstream database that captures changes made to the dbs1.net
source database. The capture process in this example does not use a database link to dbs1.net
.
Complete the following steps:
dbs1.net
as the Streams administrator. For example, if the Streams administrator is strmadmin
, then issue the following statement:
CONNECT strmadmin/strmadminpw@dbs1.net
If you do not use a database link from the downstream database to the source database, then a Streams administrator must exist at the source database.
dbs2.net
that captures changes from dbs1.net
, then perform a build of the dbs1.net
data dictionary in the redo log. This step is optional if a capture process at dbs2.net
is already configured to capture changes from the dbs1.net
source database.
SET SERVEROUTPUT ON DECLARE scn NUMBER; BEGIN DBMS_CAPTURE_ADM.BUILD( first_scn => scn); DBMS_OUTPUT.PUT_LINE('First SCN Value = ' || scn); END; / First SCN Value = 409391
This procedure displays the valid first SCN value for the capture process that will be created at dbs2.net
. Make a note of the SCN value returned because you will use it when you create the capture process at dbs2.net
.
If you run this procedure to build the data dictionary in the redo log, then when the capture process is first started at dbs2.net
, it will create a LogMiner data dictionary using the data dictionary information in the redo log.
If you choose to build the data dictionary without displaying the valid first SCN value when the procedure completes, then you can query the V$ARCHIVED_LOG
dynamic performance view to determine a valid first SCN value for the capture process that will be created at dbs2.net
.
SELECT DISTINCT FIRST_CHANGE# FROM V$ARCHIVED_LOG WHERE DICTIONARY_BEGIN = 'YES';
Your output looks similar to the following:
FIRST_CHANGE# ------------- 409391
If more than one value is returned, then make a note of the highest value.
hr.departments
table for instantiation:
BEGIN DBMS_CAPTURE_ADM.PREPARE_TABLE_INSTANTIATION( table_name => 'hr.departments'); END; /
dbs2.net
as the Streams administrator. For example, if the Streams administrator is strmadmin
, then issue the following statement:
CONNECT strmadmin/strmadminpw@dbs2.net
BEGIN DBMS_STREAMS_ADM.SET_UP_QUEUE( queue_table => 'strmadmin.strm03_queue_table', queue_name => 'strmadmin.strm03_queue'); END; /
CREATE_CAPTURE
procedure to create the capture process and specify the value obtained in Step 2 for the first_scn
parameter:
BEGIN DBMS_CAPTURE_ADM.CREATE_CAPTURE( queue_name => 'strm03_queue', capture_name => 'strm04_capture', rule_set_name => NULL, start_scn => NULL, source_database => 'dbs1.net', use_database_link => false, first_scn => 409391, -- Use value from Step 2 logfile_assignment => 'implicit'); END; /
Running this procedure performs the following actions:
strm04_capture
at the downstream database dbs2.net
. A capture process with the same name must not exist.dbs2.net
named strm03_queue
dbs1.net
409391
. This value was obtained in Step 2. The first SCN is the lowest SCN for which a capture process can capture changes. Because a first SCN is specified, the capture process creates a new LogMiner data dictionary when it is first started, regardless of whether there are existing LogMiner data dictionaries for the same source database.dbs1.net
. Therefore, the capture process scans any new log files copied from dbs1.net
to dbs2.net
for changes that it must capture. These log files must be added to the capture process automatically using log transport services or manually using the following DDL statement:
ALTER DATABASE REGISTER LOGICAL LOGFILE file_name FOR capture_process;
Here, file_name
is the name of the redo log file and capture_process
is the name of the capture process that will use the redo log file at the downstream database. You must add redo log files manually only if the logfile_assignment
parameter is set to explicit
.
This step does not associate the capture process strm04_capture
with any rule set. A rule set will be created and associated with the capture process in the next step.
See Also:
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BEGIN DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name => 'hr.departments', streams_type => 'capture', streams_name => 'strm04_capture', queue_name => 'strm03_queue', include_dml => true, include_ddl => false, include_tagged_lcr => false, source_database => 'dbs1.net', inclusion_rule => true ); END; /
Running this procedure performs the following actions:
dbs2.net
for capture process strm04_capture
. The rule set has a system-generated name. The rule set is a positive rule set for the capture process because the inclusion_rule
parameter is set to true
.hr.departments
table, and adds the rule to the rule set for the capture process. The rule has a system-generated name. The rule is added to the positive rule set for the capture process because the inclusion_rule
parameter is set to true
.Now you can configure propagation or apply, or both, of the LCRs captured by the strm04_capture
capture process.
In this example, if you want to use an apply process to apply the LCRs at the downstream database dbs2.net
, then set the instantiation SCN for the hr.departments
table at dbs2.net
. If this table does not exist at dbs2.net
, then instantiate it at dbs2.net
.
For example, if the hr.departments
table exists at dbs2.net
, then set the instantiation SCN for the hr.departments
table at dbs2.net
by running the following procedure at the source database dbs1.net
:
CONNECT strmadmin/strmadminpw@dbs1.net DECLARE iscn NUMBER; -- Variable to hold instantiation SCN value BEGIN iscn := DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER(); DBMS_APPLY_ADM.SET_TABLE_INSTANTIATION_SCN@DBS2.NET( source_object_name => 'hr.departments', source_database_name => 'dbs1.net', instantiation_scn => iscn); END; /
After the instantiation SCN has been set, you can configure an apply process to apply LCRs for the hr.departments
table from the strm03_queue
queue. Setting the instantiation SCN for an object at a database is required only if an apply process applies LCRs for the object.
See Also:
Oracle Streams Replication Administrator's Guide for more information about instantiation |
To create a capture process that performs downstream capture, you must use the CREATE_CAPTURE
procedure. This section describes creating a downstream capture process that assigns redo log files explicitly. That is, you must use the DBMS_FILE_TRANSFER
package, FTP, or some other method to transfer redo log files from the source database to the downstream database, and then you must register these redo log files with the downstream capture process manually.
In this example, assume the following:
dbs1.net
and the downstream database is dbs2.net
.dbs2.net
uses the strm03_queue
.hr.departments
table.Complete the following steps:
dbs1.net
as the hr
user:
CONNECT hr/hr@dbs1.net
hr.departments
table:
ALTER TABLE hr.departments ADD SUPPLEMENTAL LOG DATA (PRIMARY KEY) COLUMNS;
Primary key supplemental logging is required for the hr.departments
table because this example creates a capture processes that captures changes to this table.
dbs1.net
as the Streams administrator. For example, if the Streams administrator is strmadmin
, then issue the following statement:
CONNECT strmadmin/strmadminpw@dbs1.net
If you do not use a database link from the downstream database to the source database, then a Streams administrator must exist at the source database.
dbs2.net
that captures changes from dbs1.net
, then perform a build of the dbs1.net
data dictionary in the redo log. This step is optional if a capture process at dbs2.net
is already configured to capture changes from the dbs1.net
source database.
SET SERVEROUTPUT ON DECLARE scn NUMBER; BEGIN DBMS_CAPTURE_ADM.BUILD( first_scn => scn); DBMS_OUTPUT.PUT_LINE('First SCN Value = ' || scn); END; / First SCN Value = 409391
This procedure displays the valid first SCN value for the capture process that will be created at dbs2.net
. Make a note of the SCN value returned because you will use it when you create the capture process at dbs2.net
.
If you run this procedure to build the data dictionary in the redo log, then when the capture process is first started at dbs2.net
, it will create a LogMiner data dictionary using the data dictionary information in the redo log.
hr.departments
table for instantiation:
BEGIN DBMS_CAPTURE_ADM.PREPARE_TABLE_INSTANTIATION( table_name => 'hr.departments'); END; /
dbs2.net
as the Streams administrator. For example, if the Streams administrator is strmadmin
, then issue the following statement:
CONNECT strmadmin/strmadminpw@dbs2.net
CREATE_CAPTURE
procedure to create the capture process and specify the value obtained in Step 2 for the first_scn
parameter:
BEGIN DBMS_CAPTURE_ADM.CREATE_CAPTURE( queue_name => 'strm03_queue', capture_name => 'strm05_capture', rule_set_name => NULL, start_scn => NULL, source_database => 'dbs1.net', use_database_link => false, first_scn => 409391, -- Use value from Step 2 logfile_assignment => 'explicit'); END; /
Running this procedure performs the following actions:
strm05_capture
at the downstream database dbs2.net
. A capture process with the same name must not exist.dbs2.net
named strm03_queue
dbs1.net
409391
. This value was obtained in Step 2. The first SCN is the lowest SCN for which a capture process can capture changes. Because a first SCN is specified, the capture process creates a new LogMiner data dictionary when it is first started, regardless of whether there are existing LogMiner data dictionaries for the same source database.dbs1.net
must be assigned to the capture process explicitly. After a redo log file has been transferred to the computer running the downstream database, you assign the log file to the capture process explicitly using the following DDL statement:
ALTER DATABASE REGISTER LOGICAL LOGFILE file_name FOR capture_process;
Here, file_name
is the name of the redo log file and capture_process
is the name of the capture process that will use the redo log file at the downstream database. You must add redo log files manually if the logfile_assignment
parameter is set to explicit
.
This step does not associate the capture process strm05_capture
with any rule set. A rule set will be created and associated with the capture process in the next step.
See Also:
|
BEGIN DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name => 'hr.departments', streams_type => 'capture', streams_name => 'strm05_capture', queue_name => 'strm03_queue', include_dml => true, include_ddl => false, include_tagged_lcr => false, source_database => 'dbs1.net', inclusion_rule => true ); END; /
Running this procedure performs the following actions:
dbs2.net
for capture process strm04_capture
. The rule set has a system-generated name. The rule set is a positive rule set for the capture process because the inclusion_rule
parameter is set to true
.hr.departments
table, and adds the rule to the rule set for the capture process. The rule has a system-generated name. The rule is added to the positive rule set for the capture process because the inclusion_rule
parameter is set to true
.dbs1.net
that contains the first SCN for the downstream capture process is archived, transfer the archived redo log file to the computer running the downstream database. The BUILD
procedure in Step 4 determined the first SCN for the downstream capture process. If the redo log file is not yet archived, you can run the ALTER
SYSTEM
SWITCH
LOGFILE
statement on the database to archive it.
You can run the following query at dbs1.net
to identify the archived redo log file that contains the first SCN for the downstream capture process:
COLUMN NAME HEADING 'Archived Redo Log|File Name' FORMAT A50 COLUMN FIRST_CHANGE# HEADING 'First SCN' FORMAT 999999999 SELECT NAME, FIRST_CHANGE# FROM V$ARCHIVED_LOG WHERE FIRST_CHANGE# IS NOT NULL AND DICTIONARY_BEGIN = 'YES';
Transfer the archived redo log file with a FIRST_CHANGE#
that matches the first SCN returned in Step 4 to the computer running the downstream capture process.
dbs2.net
, connect as an administrative user and assign the transferred redo log file to the capture process. For example, if the redo log file is /oracle/logs_from_dbs1/1_10_486574859.dbf
, then issue the following statement:
ALTER DATABASE REGISTER LOGICAL LOGFILE '/oracle/logs_from_dbs1/1_10_486574859.dbf' FOR 'strm05_capture';
Now you can configure propagation or apply, or both, of the LCRs captured by the strm05_capture
capture process.
In this example, if you want to use an apply process to apply the LCRs at the downstream database dbs2.net
, then set the instantiation SCN for the hr.departments
table at dbs2.net
. If this table does not exist at dbs2.net
, then instantiate it at dbs2.net
.
For example, if the hr.departments
table exists at dbs2.net
, then set the instantiation SCN for the hr.departments
table at dbs2.net
by running the following procedure at the source database dbs1.net
:
CONNECT strmadmin/strmadminpw@dbs1.net DECLARE iscn NUMBER; -- Variable to hold instantiation SCN value BEGIN iscn := DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER(); DBMS_APPLY_ADM.SET_TABLE_INSTANTIATION_SCN@DBS2.NET( source_object_name => 'hr.departments', source_database_name => 'dbs1.net', instantiation_scn => iscn); END; /
After the instantiation SCN has been set, you can configure an apply process to apply LCRs for the hr.departments
table from the strm03_queue
queue. Setting the instantiation SCN for an object at a database is required only if an apply process applies LCRs for the object.
See Also:
Oracle Streams Replication Administrator's Guide for more information about instantiation |
This example runs the CREATE_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to create a local capture process with a start SCN set to 223525
. This example assumes that there is at least one local capture processes at the database, and that this capture process has taken at least one checkpoint. You can always specify a start SCN for a new capture process that is equal to or greater than the current SCN of the source database. If you want to specify a start SCN that is lower than the current SCN of the database, then the specified start SCN must be higher than the lowest first SCN for an existing local capture process that has been started successfully at least once and has taken at least one checkpoint.
You can determine the first SCN for existing capture processes, and whether these capture processes have taken a checkpoint, by running the following query:
SELECT CAPTURE_NAME, FIRST_SCN, MAX_CHECKPOINT_SCN FROM DBA_CAPTURE;
Your output looks similar to the following:
CAPTURE_NAME FIRST_SCN MAX_CHECKPOINT_SCN ------------------------------ ---------- ------------------ CAPTURE_SIMP 223522 230825
These results show that the capture_simp
capture process has a first SCN of 223522
. Also, this capture process has taken a checkpoint because the MAX_CHECKPOINT_SCN
value is non-NULL
. Therefore, the start SCN for the new capture process can be set to 223522
or higher.
Run the following procedure to create the capture process:
BEGIN DBMS_CAPTURE_ADM.CREATE_CAPTURE( queue_name => 'strm01_queue', capture_name => 'strm05_capture', rule_set_name => 'strmadmin.strm01_rule_set', start_scn => 223525, source_database => NULL, use_database_link => false, first_scn => NULL); END; /
Running this procedure performs the following actions:
strm05_capture
. A capture process with the same name must not exist.strm01_queue
strm01_rule_set
. This rule set is the positive rule set for the capture process.223525
as the start SCN for the capture process. The new capture process uses the same LogMiner data dictionary as one of the existing capture processes. Streams automatically chooses which LogMiner data dictionary to share with the new capture process. Because the first_scn
parameter was set to NULL
, the first SCN for the new capture process is the same as the first SCN of the existing capture process whose LogMiner data dictionary was shared. In this example, the existing capture process is capture_simp
.source_database
parameter is set to NULL
. For a local capture process, you also may specify the global name of the local database for this parameter.
This section contains instructions for starting, stopping and dropping a capture process. It contains the following topics:
You run the START_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to start an existing capture process. For example, the following procedure starts a capture process named strm01_capture
:
BEGIN DBMS_CAPTURE_ADM.START_CAPTURE( capture_name => 'strm01_capture'); END; /
You run the STOP_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to stop an existing capture process. For example, the following procedure stops a capture process named strm01_capture
:
BEGIN DBMS_CAPTURE_ADM.STOP_CAPTURE( capture_name => 'strm01_capture'); END; /
You run the DROP_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package to drop an existing capture process. For example, the following procedure drops a capture process named strm02_capture
:
BEGIN DBMS_CAPTURE_ADM.DROP_CAPTURE( capture_name => 'strm02_capture', drop_unused_rule_sets => true); END; /
Because the drop_unused_rule_sets
parameter is set to true
, this procedure also drops any rule sets used by the strm02_capture
capture process, unless a rule set is used by another Streams client. If the drop_unused_rule_sets
parameter is set to true
, then both the positive and negative rule set for the capture process may be dropped. If this procedure drops a rule set, then it also drops any rules in the rule set that are not in another rule set.
This section contains instructions for completing the following tasks:
You can specify one positive rule set and one negative rule set for a capture process. The capture process captures a change if it evaluates to TRUE
for at least one rule in the positive rule set and evaluates to FALSE
for all the rules in the negative rule set. The negative rule set is evaluated before the positive rule set.
You specify an existing rule set as the positive rule set for an existing capture process using the rule_set_name
parameter in the ALTER_CAPTURE
procedure. This procedure is in the DBMS_CAPTURE_ADM
package.
For example, the following procedure sets the positive rule set for a capture process named strm01_capture
to strm02_rule_set
.
BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm01_capture', rule_set_name => 'strmadmin.strm02_rule_set'); END; /
You specify an existing rule set as the negative rule set for an existing capture process using the negative_rule_set_name
parameter in the ALTER_CAPTURE
procedure. This procedure is in the DBMS_CAPTURE_ADM
package.
For example, the following procedure sets the negative rule set for a capture process named strm01_capture
to strm03_rule_set
.
BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm01_capture', negative_rule_set_name => 'strmadmin.strm03_rule_set'); END; /
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.
The following is an example that runs the ADD_TABLE_RULES
procedure in the DBMS_STREAMS_ADM
package to add rules to the positive rule set of a capture process named strm01_capture
:
BEGIN DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name => 'hr.departments', streams_type => 'capture', streams_name => 'strm01_capture', queue_name => 'strm01_queue', include_dml => true, include_ddl => true, inclusion_rule => true); END; /
Running this procedure performs the following actions:
TRUE
for DML changes to the hr.departments
table, and the other rule evaluates to TRUE
for DDL changes to the hr.departments
table. The rule names are specified by the system.inclusion_rule
parameter is set to true
hr.departments
table for instantiation by running the PREPARE_TABLE_INSTANTIATION
procedure in the DBMS_CAPTURE_ADM
package. If the capture process is performing downstream capture, then the table is prepared for instantiation only if the downstream capture process uses a database link to the source database. If a downstream capture process does not use a database link to the source database, then the table must be prepared for instantiation manually.The following is an example that runs the ADD_TABLE_RULES
procedure in the DBMS_STREAMS_ADM
package to add rules to the negative rule set of a capture process named strm01_capture
:
BEGIN DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name => 'hr.job_history', streams_type => 'capture', streams_name => 'strm01_capture', queue_name => 'strm01_queue', include_dml => true, include_ddl => true, inclusion_rule => false); END; /
Running this procedure performs the following actions:
TRUE
for DML changes to the hr.job_history
table, and the other rule evaluates to TRUE
for DDL changes to the hr.job_history
table. The rule names are specified by the system.inclusion_rule
parameter is set to false
.You specify that you want to remove a rule from a rule set for an existing capture process by running the REMOVE_RULE
procedure in the DBMS_STREAMS_ADM
package. For example, the following procedure removes a rule named departments3
from the positive rule set of a capture process named strm01_capture
.
BEGIN DBMS_STREAMS_ADM.REMOVE_RULE( rule_name => 'departments3', streams_type => 'capture', streams_name => 'strm01_capture', drop_unused_rule => true, inclusion_rule => true); END; /
In this example, the drop_unused_rule
parameter in the REMOVE_RULE
procedure is set to true
, which is the default setting. Therefore, if the rule being removed is not in any other rule set, then it will be dropped from the database. If the drop_unused_rule
parameter is set to false
, then the rule is removed from the rule set, but it is not dropped from the database.
If the inclusion_rule
parameter is set to false
, then the REMOVE_RULE
procedure removes the rule from the negative rule set for the capture process, not the positive rule set.
In addition, if you want to remove all of the rules in a rule set for the capture process, then specify NULL
for the rule_name
parameter when you run the REMOVE_RULE
procedure.
You specify that you want to remove a rule set from an existing capture process using the ALTER_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package. This procedure can remove the positive rule set, negative rule set, or both. Specify true
for the remove_rule_set
parameter to remove the positive rule set for the capture process. Specify true
for the remove_negative_rule_set
parameter to remove the negative rule set for the capture process.
For example, the following procedure removes both the positive and negative rule set from a capture process named strm01_capture
.
BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm01_capture', remove_rule_set => true, remove_negative_rule_set => true); END; /
Set a capture process parameter using the SET_PARAMETER
procedure in the DBMS_CAPTURE_ADM
package. Capture process parameters control the way a capture process operates.
For example, the following procedure sets the parallelism
parameter for a capture process named strm01_capture
to 3
.
BEGIN DBMS_CAPTURE_ADM.SET_PARAMETER( capture_name => 'strm01_capture', parameter => 'parallelism', value => '3'); END; /
Note:
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See Also:
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The capture user is the user who captures all DML changes and DDL changes that satisfy the capture process rule sets. Set the capture user for a capture process using the capture_user
parameter in the ALTER_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package.
To change the capture user, the user who invokes the ALTER_CAPTURE
procedure must be granted DBA
role. Only the SYS
user can set the capture_user
to SYS
.
For example, the following procedure sets the capture user for a capture process named strm01_capture
to hr
.
BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm01_capture', capture_user => 'hr'); END; /
Running this procedure grants the new capture user enqueue privilege on the queue used by the capture process and configures the user as a secure queue user of the queue. In addition, make sure the capture user has the following privileges:
These privileges must be granted directly to the capture user. They cannot be granted through roles.
Supplemental logging must be specified for certain columns at a source database for changes to the columns to be applied successfully at a destination database. Typically, supplemental logging is required in Streams replication environments, but it may be required in any environment that processes captured events with an apply process. You use the ALTER
DATABASE
statement to specify supplemental logging for all tables in a database, and you use the ALTER
TABLE
statement to specify supplemental logging for a particular table.
See Also:
Oracle Streams Replication Administrator's Guide for more information about specifying supplemental logging |
You can add an archived redo log file to a capture process manually using the following statement:
ALTER DATABASE REGISTER LOGICAL LOGFILE file_name FOR capture_process;
Here, file_name
is the name of the archived redo log file being added and capture_process
is the name of the capture process that will use the redo log file at the downstream database. The capture_process
is equivalent to the logminer_session_name
and must be specified. The redo log file must be present at the site running capture process.
For example, to add the /usr/log_files/1_3_486574859.dbf
archived redo log file to a capture process named strm03_capture
, issue the following statement:
ALTER DATABASE REGISTER LOGICAL LOGFILE '/usr/log_files/1_3_486574859.dbf' FOR 'strm03_capture';
See Also:
Oracle Database SQL Reference for more information about the |
This section contains the following topics:
You can set the first SCN for an existing capture process using the ALTER_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package. The specified first SCN must meet the following requirements:
You can determine the current first SCN, applied SCN, and required checkpoint SCN for each capture process in a database using the following query:
SELECT CAPTURE_NAME, FIRST_SCN, APPLIED_SCN, REQUIRED_CHECKPOINT_SCN FROM DBA_CAPTURE;
When you reset a first SCN for a capture process, information below the new first SCN setting is purged from the LogMiner dictionary for the capture process automatically. Therefore, after the first SCN is reset for a capture process, the start SCN for the capture process cannot be set lower than the new first SCN. Also, redo log files prior that contain information prior to the new first SCN setting will never be needed by the capture process.
For example, the following procedure sets the first SCN for a capture process named strm01_capture
to 351232
.
BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm01_capture', first_scn => 351232); END; /
You can set the start SCN for an existing capture process using the ALTER_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package. Typically, you reset the start SCN for a capture process if point-in-time recovery must be performed on one of the destination databases that receive changes from the capture process.
The specified start SCN must be greater than or equal to the first SCN for the capture process. You can determine the first SCN for each capture process in a database using the following query:
SELECT CAPTURE_NAME, FIRST_SCN FROM DBA_CAPTURE;
Also, when you reset a start SCN for a capture process, make sure the required redo log files are available to the capture process.
For example, the following procedure sets the start SCN for a capture process named strm01_capture
to 750338
.
BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm01_capture', start_scn => 750338); END; /
See Also:
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You specify whether an existing downstream capture process uses a database link to the source database for administrative purposes using the ALTER_CAPTURE
procedure in the DBMS_CAPTURE_ADM
package. Set the use_database_link
parameter to true
to specify that the downstream capture process uses a database link, or you set the use_database_link
parameter to false
to specify that the downstream capture process does not use a database link.
If you want a capture process that is not using a database link currently to begin using a database link, then specify true
for the use_database_link
parameter. In this case, a database link with the same name as the global name as the source database must exist at the downstream database.
If you want a capture process that is using a database link currently to stop using a database link, then specify false
for the use_database_link
parameter. In this case, some administration must be performed manually after you alter the capture process. For example, if you add new capture process rules using the DBMS_STREAMS_ADM
package, then you must prepare the objects relating to the rules for instantiation manually at the source database.
If you specify NULL
for the use_database_link
parameter, then the current value of this parameter for the capture process is not changed.
The example in "Creating a Downstream Capture Process That Does Not Use a Database Link" created the capture process strm04_capture
and specified that this capture process does not use a database link. To create a database link to the source database dbs1.net
and specify that this capture process uses the database link, complete the following actions:
CREATE DATABASE LINK dbs1.net CONNECT TO strmadmin IDENTIFIED BY strmadminpw USING 'dbs1.net'; BEGIN DBMS_CAPTURE_ADM.ALTER_CAPTURE( capture_name => 'strm04_capture', use_database_link => true); END; /
You can use the INCLUDE_EXTRA_ATTRIBUTE
procedure in the DBMS_CAPTURE_ADM
package to instruct a capture process to capture one or more extra attributes. You also can use this procedure to instruct a capture process to exclude an extra attribute that it is capturing currently.
The extra attributes are the following:
This section contains instructions for completing the following tasks:
See Also:
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To instruct a capture process named strm01_capture
to include the transaction name in each captured LCR, run the following procedure:
BEGIN DBMS_CAPTURE_ADM.INCLUDE_EXTRA_ATTRIBUTE( capture_name => 'strm01_capture', attribute_name => 'tx_name', include => true); END; /
To instruct a capture process named strm01_capture
to exclude the transaction name from each captured LCR, run the following procedure:
BEGIN DBMS_CAPTURE_ADM.INCLUDE_EXTRA_ATTRIBUTE( capture_name => 'strm01_capture', attribute_name => 'tx_name', include => false); END; /