24 Monitoring Oracle Streams Implicit Capture

Displaying the Queue, Rule Sets, and Status of Each Capture Process

You can display the following information about each capture process in a database by running the query in this section:

• The capture process name

• The name of the queue used by the capture process

• The name of the positive rule set used by the capture process

• The name of the negative rule set used by the capture process

• The status of the capture process, which can be ENABLED, DISABLED, or ABORTED

To display this general information about each capture process in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN QUEUE_NAME HEADING 'Capture|Process|Queue' FORMAT A15
COLUMN RULE_SET_NAME HEADING 'Positive|Rule Set' FORMAT A15
COLUMN NEGATIVE_RULE_SET_NAME HEADING 'Negative|Rule Set' FORMAT A15
COLUMN STATUS HEADING 'Capture|Process|Status' FORMAT A15

SELECT CAPTURE_NAME, QUEUE_NAME, RULE_SET_NAME, NEGATIVE_RULE_SET_NAME, STATUS 
   FROM DBA_CAPTURE;

Your output looks similar to the following:

Capture         Capture                                         Capture
Process         Process         Positive        Negative        Process
Name            Queue           Rule Set        Rule Set        Status
--------------- --------------- --------------- --------------- ---------------
STRM01_CAPTURE  STREAMS_QUEUE   RULESET$_25     RULESET$_36     ENABLED

If the status of a capture process is ABORTED, then you can query the ERROR_NUMBER and ERROR_MESSAGE columns in the DBA_CAPTURE data dictionary view to determine the error.

Displaying Change Capture Information About Each Capture Process

The query in this section displays the following information about each capture process in a database:

• The name of the capture process.

• The process number CPnn, where nn can include letters and numbers

• The session identifier.

• The serial number of the session.

• The current state of the capture process

  See "Capture Process States".

• The total number of redo entries passed by LogMiner to the capture process for detailed rule evaluation. A capture process converts a redo entry into a message and performs detailed rule evaluation on the message when capture process prefiltering cannot discard the change.

• The total number LCRs enqueued since the capture process was last started.

To display this information for each capture process in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A7
COLUMN PROCESS_NAME HEADING 'Capture|Process|Number' FORMAT A7
COLUMN SID HEADING 'Session|ID' FORMAT 9999
COLUMN SERIAL# HEADING 'Session|Serial|Number' FORMAT 9999
COLUMN STATE HEADING 'State' FORMAT A20
COLUMN TOTAL_MESSAGES_CAPTURED HEADING 'Redo|Entries|Evaluated|In Detail' FORMAT 9999999
COLUMN TOTAL_MESSAGES_ENQUEUED HEADING 'Total|LCRs|Enqueued' FORMAT 9999999999

SELECT c.CAPTURE_NAME,
       SUBSTR(s.PROGRAM,INSTR(s.PROGRAM,'(')+1,4) PROCESS_NAME, 
       c.SID,
       c.SERIAL#, 
       c.STATE,
       c.TOTAL_MESSAGES_CAPTURED,
       c.TOTAL_MESSAGES_ENQUEUED 
  FROM V$STREAMS_CAPTURE c, V$SESSION s
  WHERE c.SID = s.SID AND
        c.SERIAL# = s.SERIAL#;

Your output looks similar to the following:

Redo
        Capture         Session                        Entries       Total
Capture Process Session  Serial                      Evaluated        LCRs
Name    Number       ID  Number State                In Detail    Enqueued
------- ------- ------- ------- -------------------- --------- -----------
CAPTURE CP01        954       3 CAPTURING CHANGES      3719085     3389713
_HNS

The number of redo entries scanned can be higher than the number of DML and DDL redo entries captured by a capture process. Only DML and DDL redo entries that satisfy the rule sets of a capture process are captured and enqueued into the capture process queue. Also, the total LCRs enqueued includes LCRs that contain transaction control statements. These row LCRs contain directives such as COMMIT and ROLLBACK. Therefore, the total LCRs enqueued is a number higher than the number of row changes and DDL changes enqueued by a capture process.

Displaying State Change and Message Creation Time for Each Capture Process

The query in this section displays the following information for each capture process in a database:

• The name of the capture process

• The current state of the capture process

  See "Capture Process States".

• The date and time when the capture process state last changed

• The date and time when the capture process last created an LCR

To display this information for each capture process in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A15
COLUMN STATE HEADING 'State' FORMAT A27
COLUMN STATE_CHANGED HEADING 'State|Change Time'
COLUMN CREATE_MESSAGE HEADING 'Last Message|Create Time'

SELECT CAPTURE_NAME,
       STATE,
       TO_CHAR(STATE_CHANGED_TIME, 'HH24:MI:SS MM/DD/YY') STATE_CHANGED,
       TO_CHAR(CAPTURE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') CREATE_MESSAGE
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Capture                                     State             Last Message
Name            State                       Change Time       Create Time
--------------- --------------------------- ----------------- -----------------
CAPTURE_SIMP    CAPTURING CHANGES           13:24:42 11/08/04 13:24:41 11/08/04

Displaying Elapsed Time Performing Capture Operations for Each Capture Process

The query in this section displays the following information for each capture process in a database:

• The name of the capture process

• The elapsed capture time, which is the amount of time (in seconds) spent scanning for changes in the redo log since the capture process was last started

• The elapsed rule evaluation time, which is the amount of time (in seconds) spent evaluating rules since the capture process was last started

• The elapsed enqueue time, which is the amount of time (in seconds) spent enqueuing messages since the capture process was last started

• The elapsed LCR creation time, which is the amount of time (in seconds) spent creating logical change records (LCRs) since the capture process was last started

• The elapsed pause time, which is the amount of time (in seconds) spent paused for flow control since the capture process was last started

To display this information for each capture process in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A15
COLUMN ELAPSED_CAPTURE_TIME HEADING 'Elapsed|Capture|Time' FORMAT 99999999.99
COLUMN ELAPSED_RULE_TIME HEADING 'Elapsed|Rule|Evaluation|Time' FORMAT 99999999.99
COLUMN ELAPSED_ENQUEUE_TIME HEADING 'Elapsed|Enqueue|Time' FORMAT 99999999.99
COLUMN ELAPSED_LCR_TIME HEADING 'Elapsed|LCR|Creation|Time' FORMAT 99999999.99
COLUMN ELAPSED_PAUSE_TIME HEADING 'Elapsed|Pause|Time' FORMAT 99999999.99

SELECT CAPTURE_NAME,
       (ELAPSED_CAPTURE_TIME/100) ELAPSED_CAPTURE_TIME,
       (ELAPSED_RULE_TIME/100) ELAPSED_RULE_TIME,
       (ELAPSED_ENQUEUE_TIME/100) ELAPSED_ENQUEUE_TIME,
       (ELAPSED_LCR_TIME/100) ELAPSED_LCR_TIME,
       (ELAPSED_PAUSE_TIME/100) ELAPSED_PAUSE_TIME
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Elapsed                   Elapsed
                     Elapsed         Rule      Elapsed          LCR      Elapsed
Capture              Capture   Evaluation      Enqueue     Creation        Pause
Name                    Time         Time         Time         Time         Time
--------------- ------------ ------------ ------------ ------------ ------------
STM1$CAP             1213.92          .04        33.84       185.25       600.60

Displaying Information About Each Downstream Capture Process

A downstream capture is a capture process that runs on a database other than the source database. You can display the following information about each downstream capture process in a database by running the query in this section:

• The capture process name

• The source database of the changes captured by the capture process

• The name of the queue used by the capture process

• The status of the capture process, which can be ENABLED, DISABLED, or ABORTED

• Whether the downstream capture process uses a database link to the source database for administrative actions

To display this information about each downstream capture process in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A15
COLUMN QUEUE_NAME HEADING 'Capture|Process|Queue' FORMAT A15
COLUMN STATUS HEADING 'Capture|Process|Status' FORMAT A15
COLUMN USE_DATABASE_LINK HEADING 'Uses|Database|Link?' FORMAT A8

SELECT CAPTURE_NAME, 
       SOURCE_DATABASE, 
       QUEUE_NAME, 
       STATUS, 
       USE_DATABASE_LINK
   FROM DBA_CAPTURE
   WHERE CAPTURE_TYPE = 'DOWNSTREAM';

Your output looks similar to the following:

Capture                              Capture         Capture         Uses
Process         Source               Process         Process         Database
Name            Database             Queue           Status          Link?
--------------- -------------------- --------------- --------------- --------
STRM03_CAPTURE  DBS1.EXAMPLE.COM     STRM03_QUEUE    ENABLED         YES

In this case, the source database for the capture process is dbs1.example.com, but the local database running the capture process is not dbs1.example.com. Also, the capture process returned by this query uses a database link to the source database to perform administrative actions. The database link name is the same as the global name of the source database, which is dbs1.example.com in this case.

If the status of a capture process is ABORTED, then you can query the ERROR_NUMBER and ERROR_MESSAGE columns in the DBA_CAPTURE data dictionary view to determine the error.

Displaying the Registered Redo Log Files for Each Capture Process

You can display information about the archived redo log files that are registered for each capture process in a database by running the query in this section. This query displays information about these files for both local capture processes and downstream capture processes.

The query displays the following information for each registered archived redo log file:

• The name of a capture process that uses the file

• The source database of the file

• The sequence number of the file

• The name and location of the file at the local site

• Whether the file contains the beginning of a data dictionary build

• Whether the file contains the end of a data dictionary build

To display this information about each registered archive redo log file in a database, run the following query:

COLUMN CONSUMER_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A10
COLUMN SEQUENCE# HEADING 'Sequence|Number' FORMAT 99999
COLUMN NAME HEADING 'Archived Redo Log|File Name' FORMAT A20
COLUMN DICTIONARY_BEGIN HEADING 'Dictionary|Build|Begin' FORMAT A10
COLUMN DICTIONARY_END HEADING 'Dictionary|Build|End' FORMAT A10

SELECT r.CONSUMER_NAME,
       r.SOURCE_DATABASE,
       r.SEQUENCE#, 
       r.NAME, 
       r.DICTIONARY_BEGIN, 
       r.DICTIONARY_END 
  FROM DBA_REGISTERED_ARCHIVED_LOG r, DBA_CAPTURE c
  WHERE r.CONSUMER_NAME = c.CAPTURE_NAME;  

Your output looks similar to the following:

Capture                                                  Dictionary Dictionary
Process         Source     Sequence Archived Redo Log    Build      Build
Name            Database     Number File Name            Begin      End
--------------- ---------- -------- -------------------- ---------- ----------
STRM02_CAPTURE  DBS2.EXAMP       15 /orc/dbs/log/arch2_1 NO         NO
                LE.COM              _15_478347508.arc
STRM02_CAPTURE  DBS2.EXAMP       16 /orc/dbs/log/arch2_1 NO         NO
                LE.COM              _16_478347508.arc 
STRM03_CAPTURE  DBS1.EXAMP       45 /remote_logs/arch1_1 YES        YES
                LE.COM              _45_478347335.arc
STRM03_CAPTURE  DBS1.EXAMP       46 /remote_logs/arch1_1 NO         NO
                LE.COM              _46_478347335.arc
STRM03_CAPTURE  DBS1.EXAMP       47 /remote_logs/arch1_1 NO         NO
                LE.COM              _47_478347335.arc

Assume that this query was run at the dbs2.example.com database, and that strm02_capture is a local capture process, and strm03_capture is a downstream capture process. The source database for the strm03_capture downstream capture process is dbs1.example.com. This query shows that there are two registered archived redo log files for strm02_capture and three registered archived redo log files for strm02_capture. This query shows the name and location of each of these files in the local file system.

Displaying the Redo Log Files that Are Required by Each Capture Process

A capture process needs the redo log file that includes the required checkpoint SCN, and all subsequent redo log files. You can query the REQUIRED_CHECKPOINT_SCN column in the DBA_CAPTURE data dictionary view to determine the required checkpoint SCN for a capture process. Redo log files prior to the redo log file that contains the required checkpoint SCN are no longer needed by the capture process. These redo log files can be stored offline if they are no longer needed for any other purpose. If you reset the start SCN for a capture process to a lower value in the future, then these redo log files might be needed.

The query displays the following information for each required archived redo log file:

• The name of a capture process that uses the file

• The source database of the file

• The sequence number of the file

• The name and location of the required redo log file at the local site

To display this information about each required archive redo log file in a database, run the following query:

COLUMN CONSUMER_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A10
COLUMN SEQUENCE# HEADING 'Sequence|Number' FORMAT 99999
COLUMN NAME HEADING 'Required|Archived Redo Log|File Name' FORMAT A40

SELECT r.CONSUMER_NAME,
       r.SOURCE_DATABASE,
       r.SEQUENCE#, 
       r.NAME 
  FROM DBA_REGISTERED_ARCHIVED_LOG r, DBA_CAPTURE c
  WHERE r.CONSUMER_NAME =  c.CAPTURE_NAME AND
        r.NEXT_SCN      >= c.REQUIRED_CHECKPOINT_SCN;  

Your output looks similar to the following:

Capture                             Required
Process         Source     Sequence Archived Redo Log
Name            Database     Number File Name
--------------- ---------- -------- ----------------------------------------
STRM02_CAPTURE  DBS2.EXAMP       16 /orc/dbs/log/arch2_1_16_478347508.arc
                LE.COM
STRM03_CAPTURE  DBS1.EXAMP       47 /remote_logs/arch1_1_47_478347335.arc
                LE.COM

Displaying SCN Values for Each Redo Log File Used by Each Capture Process

You can display information about the SCN values for archived redo log files that are registered for each capture process in a database by running the query in this section. This query displays information the SCN values for these files for both local capture processes and downstream capture processes. This query also identifies redo log files that are no longer needed by any capture process at the local database.

The query displays the following information for each registered archived redo log file:

• The capture process name of a capture process that uses the file

• The name and location of the file at the local site

• The lowest SCN value for the information contained in the redo log file

• The lowest SCN value for the next redo log file in the sequence

• Whether the redo log file is purgeable

To display this information about each registered archive redo log file in a database, run the following query:

COLUMN CONSUMER_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN NAME HEADING 'Archived Redo Log|File Name' FORMAT A25
COLUMN FIRST_SCN HEADING 'First SCN' FORMAT 99999999999
COLUMN NEXT_SCN HEADING 'Next SCN' FORMAT 99999999999
COLUMN PURGEABLE HEADING 'Purgeable?' FORMAT A10
 
SELECT r.CONSUMER_NAME,
       r.NAME, 
       r.FIRST_SCN,
       r.NEXT_SCN,
       r.PURGEABLE 
  FROM DBA_REGISTERED_ARCHIVED_LOG r, DBA_CAPTURE c
  WHERE r.CONSUMER_NAME = c.CAPTURE_NAME;

Your output looks similar to the following:

Capture
Process         Archived Redo Log
Name            File Name                    First SCN     Next SCN Purgeable?
--------------- ------------------------- ------------ ------------ ----------
CAPTURE_SIMP    /private1/ARCHIVE_LOGS/1_       509686       549100 YES
                3_502628294.dbf
 
CAPTURE_SIMP    /private1/ARCHIVE_LOGS/1_       549100       587296 YES
                4_502628294.dbf
 
CAPTURE_SIMP    /private1/ARCHIVE_LOGS/1_       587296       623107 NO
                5_502628294.dbf

The redo log files with YES for Purgeable? for all capture processes will never be needed by any capture process at the local database. These redo log files can be removed without affecting any existing capture process at the local database. The redo log files with NO for Purgeable? for one or more capture processes must be retained.

Displaying the Last Archived Redo Entry Available to Each Capture Process

For a local capture process, the last archived redo entry available is the last entry from the online redo log flushed to an archived log file. For a downstream capture process, the last archived redo entry available is the redo entry with the most recent system change number (SCN) in the last archived log file added to the LogMiner session used by the capture process.

You can display the following information about the last redo entry that was made available to each capture process by running the query in this section:

• The name of the capture process

• The identification number of the LogMiner session used by the capture process

• The highest SCN available for the capture process

  For local capture, this SCN is the last redo SCN flushed to the logfiles. For downstream capture, this SCN is the last SCN added to LogMiner through the archive logs.

• The timestamp of the highest SCN available for the capture process

  For local capture, this timestamp is the time the SCN was written to the logfile. For downstream capture, this timestamp is the time of the most recent archive log (containing the most recent SCN) available to LogMiner.

The information displayed by this query is valid only for an enabled capture process.

Run the following query to display this information for each capture process:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A20
COLUMN LOGMINER_ID HEADING 'LogMiner ID' FORMAT 9999
COLUMN AVAILABLE_MESSAGE_NUMBER HEADING 'Highest|Available SCN' FORMAT 9999999999
COLUMN AVAILABLE_MESSAGE_CREATE_TIME HEADING 'Time of|Highest|Available SCN'

SELECT CAPTURE_NAME,
       LOGMINER_ID,
       AVAILABLE_MESSAGE_NUMBER,
       TO_CHAR(AVAILABLE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') 
         AVAILABLE_MESSAGE_CREATE_TIME
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Time of
Capture                                Highest Highest
Name                 LogMiner ID Available SCN Available SCN
-------------------- ----------- ------------- -----------------
DB1$CAP                        1       1506751 09:46:11 06/29/09

Listing the Parameter Settings for Each Capture Process

The following query displays the current setting for each capture process parameter for each capture process in a database:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A25
COLUMN PARAMETER HEADING 'Parameter' FORMAT A30
COLUMN VALUE HEADING 'Value' FORMAT A10
COLUMN SET_BY_USER HEADING 'Set by|User?' FORMAT A10

SELECT CAPTURE_NAME,
       PARAMETER, 
       VALUE,
       SET_BY_USER  
  FROM DBA_CAPTURE_PARAMETERS;

Your output looks similar to the following:

Capture
Process                                                             Set by
Name                      Parameter                      Value      User?
------------------------- ------------------------------ ---------- ----------
DB1$CAP                   DISABLE_ON_LIMIT               N          NO
DB1$CAP                   DOWNSTREAM_REAL_TIME_MINE      Y          NO
DB1$CAP                   MAXIMUM_SCN                    INFINITE   NO
DB1$CAP                   MERGE_THRESHOLD                60         NO
DB1$CAP                   MESSAGE_LIMIT                  INFINITE   NO
DB1$CAP                   MESSAGE_TRACKING_FREQUENCY     2000000    NO
DB1$CAP                   PARALLELISM                    1          NO
DB1$CAP                   SKIP_AUTOFILTERED_TABLE_DDL    Y          NO
DB1$CAP                   SPLIT_THRESHOLD                1800       NO
DB1$CAP                   STARTUP_SECONDS                0          NO
DB1$CAP                   TIME_LIMIT                     INFINITE   NO
DB1$CAP                   TRACE_LEVEL                    0          NO
DB1$CAP                   WRITE_ALERT_LOG                Y          NO

Determining the Applied SCN for All Capture Processes in a Database

The applied system change number (SCN) for a capture process is the SCN of the most recent message dequeued by the relevant apply processes. All changes below this applied SCN have been dequeued by all apply processes that apply changes captured by the capture process.

To display the applied SCN for all of the capture processes in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture Process Name' FORMAT A30
COLUMN APPLIED_SCN HEADING 'Applied SCN' FORMAT 99999999999

SELECT CAPTURE_NAME, APPLIED_SCN FROM DBA_CAPTURE;

Your output looks similar to the following:

Capture Process Name           Applied SCN
------------------------------ -----------
CAPTURE_EMP                         177154

Determining Redo Log Scanning Latency for Each Capture Process

You can find the following information about each capture process by running the query in this section:

• The redo log scanning latency, which specifies the number of seconds between the creation time of the most recent redo log entry scanned by a capture process and the current time. This number might be relatively large immediately after you start a capture process.

• The seconds since last recorded status, which is the number of seconds since a capture process last recorded its status.

• The current capture process time, which is the latest time when the capture process recorded its status.

• The message creation time, which is the time when the data manipulation language (DML) or data definition language (DDL) change generated the redo data at the source database for the most recently captured LCR.

The information displayed by this query is valid only for an enabled capture process.

Run the following query to determine the redo scanning latency for each capture process:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A10
COLUMN LATENCY_SECONDS HEADING 'Latency|in|Seconds' FORMAT 999999
COLUMN LAST_STATUS HEADING 'Seconds Since|Last Status' FORMAT 999999
COLUMN CAPTURE_TIME HEADING 'Current|Process|Time'
COLUMN CREATE_TIME HEADING 'Message|Creation Time' FORMAT 999999

SELECT CAPTURE_NAME,
       ((SYSDATE - CAPTURE_MESSAGE_CREATE_TIME)*86400) LATENCY_SECONDS,
       ((SYSDATE - CAPTURE_TIME)*86400) LAST_STATUS,
       TO_CHAR(CAPTURE_TIME, 'HH24:MI:SS MM/DD/YY') CAPTURE_TIME,       
       TO_CHAR(CAPTURE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') CREATE_TIME
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Capture    Latency               Current
Process         in Seconds Since Process           Message
Name       Seconds   Last Status Time              Creation Time
---------- ------- ------------- ----------------- -----------------
CAPTURE          4             4 12:04:13 03/01/02 12:04:13 03/01/02

The "Latency in Seconds" returned by this query is the difference between the current time (SYSDATE) and the "Message Creation Time." The "Seconds Since Last Status" returned by this query is the difference between the current time (SYSDATE) and the "Current Process Time."

Determining Message Enqueuing Latency for Each Capture Process

You can find the following information about each capture process by running the query in this section:

• The message enqueuing latency, which specifies the number of seconds between when an entry was recorded in the redo log at the source database and when the message was enqueued by the capture process

• The message creation time, which is the time when the data manipulation language (DML) or data definition language (DDL) change generated the redo data at the source database for the most recently enqueued message

• The enqueue time, which is when the capture process enqueued the message into its queue

• The message number of the enqueued message

The information displayed by this query is valid only for an enabled capture process.

Run the following query to determine the message capturing latency for each capture process:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A10
COLUMN LATENCY_SECONDS HEADING 'Latency|in|Seconds' FORMAT 999999
COLUMN CREATE_TIME HEADING 'Message Creation|Time' FORMAT A20
COLUMN ENQUEUE_TIME HEADING 'Enqueue Time' FORMAT A20
COLUMN ENQUEUE_MESSAGE_NUMBER HEADING 'Message|Number' FORMAT 9999999999

SELECT CAPTURE_NAME,
       (ENQUEUE_TIME-ENQUEUE_MESSAGE_CREATE_TIME)*86400 LATENCY_SECONDS, 
       TO_CHAR(ENQUEUE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') CREATE_TIME,
       TO_CHAR(ENQUEUE_TIME, 'HH24:MI:SS MM/DD/YY') ENQUEUE_TIME,
       ENQUEUE_MESSAGE_NUMBER
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Capture    Latency
Process         in Message Creation                            Message
Name       Seconds Time                 Enqueue Time          Number
---------- ------- -------------------- -------------------- -------
CAPTURE          0 10:56:51 03/01/02    10:56:51 03/01/02     253962

The "Latency in Seconds" returned by this query is the difference between the "Enqueue Time" and the "Message Creation Time."

Displaying Information About Rule Evaluations for Each Capture Process

You can display the following information about rule evaluation for each capture process by running the query in this section:

• The name of the capture process.

• The number of changes discarded during prefiltering since the capture process was last started. The capture process determined that these changes definitely did not satisfy the capture process rule sets during prefiltering.

• The number of changes kept during prefiltering since the capture process was last started. The capture process determined that these changes definitely satisfied the capture process rule sets during prefiltering. Such changes are converted into LCRs and enqueued into the capture process queue.

• The total number of prefilter evaluations since the capture process was last started.

• The number of undecided changes after prefiltering since the capture process was last started. These changes might or might not satisfy the capture process rule sets. Some of these changes might be filtered out after prefiltering without requiring full evaluation. Other changes require full evaluation to determine whether they satisfy the capture process rule sets.

• The number of full evaluations since the capture process was last started. Full evaluations can be expensive. Therefore, capture process performance is best when this number is relatively low.

The information displayed by this query is valid only for an enabled capture process.

Run the following query to display this information for each capture process:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A15
COLUMN TOTAL_PREFILTER_DISCARDED HEADING 'Prefilter|Changes|Discarded' 
  FORMAT 9999999999
COLUMN TOTAL_PREFILTER_KEPT HEADING 'Prefilter|Changes|Kept' FORMAT 9999999999
COLUMN TOTAL_PREFILTER_EVALUATIONS HEADING 'Prefilter|Evaluations' 
  FORMAT 9999999999
COLUMN UNDECIDED HEADING 'Undecided|After|Prefilter' FORMAT 9999999999
COLUMN TOTAL_FULL_EVALUATIONS HEADING 'Full|Evaluations' FORMAT 9999999999

SELECT CAPTURE_NAME,
       TOTAL_PREFILTER_DISCARDED,
       TOTAL_PREFILTER_KEPT,
       TOTAL_PREFILTER_EVALUATIONS,
       (TOTAL_PREFILTER_EVALUATIONS - 
         (TOTAL_PREFILTER_KEPT + TOTAL_PREFILTER_DISCARDED)) UNDECIDED,
       TOTAL_FULL_EVALUATIONS
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Prefilter   Prefilter               Undecided
Capture            Changes     Changes   Prefilter       After        Full
Name             Discarded        Kept Evaluations   Prefilter Evaluations
--------------- ---------- ----------- ----------- ----------- -----------
CAPTURE_HNS         927409     3271491     4198900           0           9

The total number of prefilter evaluations equals the sum of the prefilter changes discarded, the prefilter changes kept, and the undecided changes.

Determining Which Capture Processes Use Combined Capture and Apply

A combined capture and apply environment is efficient because the capture process acts as the propagation sender, and the buffered queue is optimized to make replication of changes more efficient.

When a capture process uses combined capture and apply, the OPTIMIZATION column in the V$STREAMS_CAPTURE data dictionary view is greater than zero. When a capture process does not use combined capture and apply, the OPTIMIZATION column is 0 (zero).

To determine whether a capture process uses combined capture and apply, run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture Name' FORMAT A30
COLUMN OPTIMIZATION HEADING 'Optimized?' FORMAT A10

SELECT CAPTURE_NAME, 
       DECODE(OPTIMIZATION,
                0, 'No',
                   'Yes') OPTIMIZATION
  FROM V$STREAMS_CAPTURE;

Your output looks similar to the following:

Capture Name                   Optimized?
------------------------------ ----------
CAPTURE_HNS                    Yes

This output indicates that the capture_hns capture process uses combined capture and apply.

Displaying Information About Split and Merge Operations

Splitting and merging an Oracle Streams destination is useful under the following conditions:

• A single capture process captures changes that are sent to two or more apply processes.

• An apply process stops accepting changes captured by the capture process. The apply process might stop accepting changes if, for example, the apply process is disabled, the database that contains the apply process goes down, there is a network problem, the computer system running the database that contains the apply process goes down, or for some other reason.

When these conditions are met, it is best to split the problem destination stream off from the other destination streams to avoid degraded performance. When the problem is corrected, the destination stream that was split off can be merged back into the other destination streams for the capture process.

By default, split and merge operations are performed automatically when Oracle Streams detects a problem destination. Two capture process parameters, split_threshold and merge_threshold, control automatic split and merge operations.

The following sections contain queries that you can run to monitor current and past automatic split and merge operations:

• Displaying the Names of the Original and Cloned Oracle Streams Components

• Displaying the Actions and Thresholds for Split and Merge Operations

• Displaying the Lag Time of the Cloned Capture Process

• Displaying Information About the Split and Merge Jobs

• Displaying Information About Past Split and Merge Operations

COLUMN ORIGINAL_CAPTURE_NAME HEADING 'Original|Capture|Process' FORMAT A15
COLUMN CLONED_CAPTURE_NAME HEADING 'Cloned|Capture|Process' FORMAT A15
COLUMN ORIGINAL_STREAMS_NAME HEADING 'Original|Streams|Name' FORMAT A15
COLUMN CLONED_STREAMS_NAME HEADING 'Cloned|Streams|Name' FORMAT A15
COLUMN STREAMS_TYPE HEADING 'Streams|Type' FORMAT A11
 
SELECT ORIGINAL_CAPTURE_NAME,
       CLONED_CAPTURE_NAME,
       ORIGINAL_STREAMS_NAME,
       CLONED_STREAMS_NAME,
       STREAMS_TYPE
 FROM DBA_STREAMS_SPLIT_MERGE;

Original        Cloned          Original        Cloned
Capture         Capture         Streams         Streams         Streams
Process         Process         Name            Name            Type
--------------- --------------- --------------- --------------- -----------
DB$CAP          CLONED$_DB$CAP_ PROPAGATION$_17 CLONED$_PROPAGA PROPAGATION
                1                               TION$_17_2

COLUMN ORIGINAL_CAPTURE_NAME HEADING 'Original|Capture|Process' FORMAT A10
COLUMN SCRIPT_STATUS HEADING 'Script|Status' FORMAT A12
COLUMN ACTION_TYPE HEADING 'Action|Type' FORMAT A7
COLUMN ACTION_THRESHOLD HEADING 'Action|Threshold' FORMAT A15
COLUMN STATUS HEADING 'Status' FORMAT A16
COLUMN STATUS_UPDATE_TIME HEADING 'Status|Update|Time' FORMAT A15
 
SELECT ORIGINAL_CAPTURE_NAME,
       SCRIPT_STATUS,
       ACTION_TYPE,
       ACTION_THRESHOLD,
       STATUS,
       STATUS_UPDATE_TIME
 FROM DBA_STREAMS_SPLIT_MERGE
 ORDER BY STATUS_UPDATE_TIME DESC;

Original                                                         Status
Capture    Script       Action  Action                           Update
Process    Status       Type    Threshold       Status           Time
---------- ------------ ------- --------------- ---------------- ---------------
DB$CAP     EXECUTED     SPLIT   1800            SPLIT DONE       31-MAR-09 01.31
                                                                 .37.133788 PM

COLUMN ORIGINAL_CAPTURE_NAME HEADING 'Original Capture Process' FORMAT A25
COLUMN CLONED_CAPTURE_NAME HEADING 'Cloned Capture Process' FORMAT A25
COLUMN LAG HEADING 'Lag' FORMAT 999999999999999
 
SELECT ORIGINAL_CAPTURE_NAME,
       CLONED_CAPTURE_NAME,
       LAG
 FROM DBA_STREAMS_SPLIT_MERGE;

Original Capture Process  Cloned Capture Process                 Lag
------------------------- ------------------------- ----------------
DB$CAP                    CLONED$_DB$CAP_1                       526

COLUMN ORIGINAL_CAPTURE_NAME HEADING 'Original|Capture|Process' FORMAT A10
COLUMN JOB_OWNER HEADING 'Job Owner' FORMAT A10
COLUMN JOB_NAME HEADING 'Job Name' FORMAT A15
COLUMN JOB_STATE HEADING 'Job State' FORMAT A15
COLUMN JOB_NEXT_RUN_DATE HEADING 'Job Next|Run Date' FORMAT A20
 
SELECT ORIGINAL_CAPTURE_NAME,
       JOB_OWNER,
       JOB_NAME,
       JOB_STATE,
       JOB_NEXT_RUN_DATE
 FROM DBA_STREAMS_SPLIT_MERGE;

Original
Capture                                               Job Next
Process    Job Owner  Job Name        Job State       Run Date
---------- ---------- --------------- --------------- --------------------
DB$CAP     SYS        STREAMS_SPLITJO SCHEDULED       01-APR-09 01.14.55.0
                      B$_3                            00000 PM -07:00
DB$CAP     SYS        STREAMS_MERGEJO SCHEDULED       01-APR-09 01.17.08.0
                      B$_6                            00000 PM -07:00

COLUMN ORIGINAL_CAPTURE_NAME HEADING 'Original|Capture|Process' FORMAT A8
COLUMN SCRIPT_STATUS HEADING 'Script|Status' FORMAT A12
COLUMN ACTION_TYPE HEADING 'Action|Type' FORMAT A8
COLUMN STATUS HEADING 'Status' FORMAT A10
COLUMN JOB_OWNER HEADING 'Job Owner' FORMAT A10
COLUMN JOB_NAME HEADING 'Job Name' FORMAT A10
COLUMN RECOVERABLE_SCRIPT_ID HEADING 'Recoverable|Script ID' FORMAT A15
 
SELECT ORIGINAL_CAPTURE_NAME,
       SCRIPT_STATUS,
       ACTION_TYPE,
       STATUS,
       JOB_OWNER,
       JOB_NAME,
       RECOVERABLE_SCRIPT_ID
 FROM DBA_STREAMS_SPLIT_MERGE_HIST;

Original
Capture  Script       Action                                    Recoverable
Process  Status       Type     Status     Job Owner  Job Name   Script ID
-------- ------------ -------- ---------- ---------- ---------- ---------------
DB1$CAP  EXECUTED     SPLIT    SPLIT DONE SYS        STREAMS_SP 6E5C6C49CDB5798
                                                     LITJOB$_9  3E040578C891704
                                                                87
 
DB1$CAP  EXECUTED     MERGE    MERGE DONE SYS        STREAMS_ME 6E5BA57554F1C4C
                                                     RGEJOB$_12 3E040578C89170A
                                                                1F

Monitoring Supplemental Logging

The following sections contain queries that you can run to monitor supplemental logging at a source database:

• Displaying Supplemental Log Groups at a Source Database

• Displaying Database Supplemental Logging Specifications

• Displaying Supplemental Logging Specified During Preparation for Instantiation

The total supplemental logging at a database is determined by the results shown in all three of the queries in these sections combined. For example, supplemental logging can be enabled for columns in a table even if no results for the table are returned by the query in the "Displaying Supplemental Log Groups at a Source Database" section. That is, supplemental logging can be enabled for the table if database supplemental logging is enabled or if the table is in a schema for which supplemental logging was enabled during preparation for instantiation.

Supplemental logging places additional column data into a redo log when an operation is performed. A capture process captures this additional information and places it in LCRs. An apply process that applies these captured LCRs might need this additional information to schedule or apply changes correctly.

COLUMN LOG_GROUP_NAME HEADING 'Log Group' FORMAT A20
COLUMN TABLE_NAME HEADING 'Table' FORMAT A15
COLUMN ALWAYS HEADING 'Conditional or|Unconditional' FORMAT A14
COLUMN LOG_GROUP_TYPE HEADING 'Type of Log Group' FORMAT A20

SELECT 
    LOG_GROUP_NAME, 
    TABLE_NAME, 
    DECODE(ALWAYS,
             'ALWAYS', 'Unconditional',
             'CONDITIONAL', 'Conditional') ALWAYS,
    LOG_GROUP_TYPE
  FROM DBA_LOG_GROUPS;

Conditional or
Log Group            Table           Unconditional  Type of Log Group
-------------------- --------------- -------------- --------------------
LOG_GROUP_DEP_PK     DEPARTMENTS     Unconditional  USER LOG GROUP
SYS_C002105          REGIONS         Unconditional  PRIMARY KEY LOGGING
SYS_C002106          REGIONS         Conditional    FOREIGN KEY LOGGING
SYS_C002110          LOCATIONS       Unonditional   ALL COLUMN LOGGING
SYS_C002111          COUNTRIES       Conditional    ALL COLUMN LOGGING
LOG_GROUP_JOBS_CR    JOBS            Conditional    USER LOG GROUP

COLUMN log_min HEADING 'Minimum|Supplemental|Logging?' FORMAT A12
COLUMN log_pk HEADING 'Primary Key|Supplemental|Logging?' FORMAT A12
COLUMN log_fk HEADING 'Foreign Key|Supplemental|Logging?' FORMAT A12
COLUMN log_ui HEADING 'Unique|Supplemental|Logging?' FORMAT A12
COLUMN log_all HEADING 'All Columns|Supplemental|Logging?' FORMAT A12

SELECT SUPPLEMENTAL_LOG_DATA_MIN log_min, 
       SUPPLEMENTAL_LOG_DATA_PK log_pk, 
       SUPPLEMENTAL_LOG_DATA_FK log_fk,
       SUPPLEMENTAL_LOG_DATA_UI log_ui,
       SUPPLEMENTAL_LOG_DATA_ALL log_all
  FROM V$DATABASE;  
  

Minimum      Primary Key  Foreign Key  Unique        All Columns
Supplemental Supplemental Supplemental Supplemental  Supplemental
Logging?     Logging?     Logging?     Logging?      Logging?
------------ ------------ ------------ ------------- ------------
YES          YES          YES          YES           NO

COLUMN TABLE_NAME HEADING 'Table Name' FORMAT A15
COLUMN log_pk HEADING 'Primary Key|Supplemental|Logging' FORMAT A12
COLUMN log_fk HEADING 'Foreign Key|Supplemental|Logging' FORMAT A12
COLUMN log_ui HEADING 'Unique|Supplemental|Logging' FORMAT A12
COLUMN log_all HEADING 'All Columns|Supplemental|Logging' FORMAT A12

SELECT TABLE_NAME,
       SUPPLEMENTAL_LOG_DATA_PK log_pk, 
       SUPPLEMENTAL_LOG_DATA_FK log_fk,
       SUPPLEMENTAL_LOG_DATA_UI log_ui,
       SUPPLEMENTAL_LOG_DATA_ALL log_all
  FROM DBA_CAPTURE_PREPARED_TABLES
  WHERE TABLE_OWNER = 'HR';  
  

Primary Key  Foreign Key  Unique         All Columns
                Supplemental Supplemental Supplemental   Supplemental
Table Name      Logging      Logging      Logging        Logging
--------------- ------------ ------------ -------------- ------------
COUNTRIES       NO           NO           NO             NO
REGIONS         IMPLICIT     IMPLICIT     IMPLICIT       NO
DEPARTMENTS     IMPLICIT     IMPLICIT     IMPLICIT       NO
LOCATIONS       EXPLICIT     NO           NO             NO
EMPLOYEES       NO           NO           NO             IMPLICIT
JOB_HISTORY     NO           NO           NO             NO
JOBS            NO           NO           NO             NO

COLUMN SCHEMA_NAME HEADING 'Schema Name' FORMAT A20
COLUMN log_pk HEADING 'Primary Key|Supplemental|Logging' FORMAT A12
COLUMN log_fk HEADING 'Foreign Key|Supplemental|Logging' FORMAT A12
COLUMN log_ui HEADING 'Unique|Supplemental|Logging' FORMAT A12
COLUMN log_all HEADING 'All Columns|Supplemental|Logging' FORMAT A12

SELECT SCHEMA_NAME,
       SUPPLEMENTAL_LOG_DATA_PK log_pk, 
       SUPPLEMENTAL_LOG_DATA_FK log_fk,
       SUPPLEMENTAL_LOG_DATA_UI log_ui,
       SUPPLEMENTAL_LOG_DATA_ALL log_all
  FROM DBA_CAPTURE_PREPARED_SCHEMAS;
  

Primary Key  Foreign Key  Unique         All Columns
                     Supplemental Supplemental Supplemental   Supplemental
Schema Name          Logging      Logging      Logging        Logging
-------------------- ------------ ------------ -------------- ------------
HR                   NO           NO           NO             IMPLICIT
OE                   IMPLICIT     IMPLICIT     IMPLICIT       NO

COLUMN log_pk HEADING 'Primary Key|Supplemental|Logging' FORMAT A12
COLUMN log_fk HEADING 'Foreign Key|Supplemental|Logging' FORMAT A12
COLUMN log_ui HEADING 'Unique|Supplemental|Logging' FORMAT A12
COLUMN log_all HEADING 'All Columns|Supplemental|Logging' FORMAT A12

SELECT SUPPLEMENTAL_LOG_DATA_PK log_pk,
       SUPPLEMENTAL_LOG_DATA_FK log_fk,
       SUPPLEMENTAL_LOG_DATA_UI log_ui,
       SUPPLEMENTAL_LOG_DATA_ALL log_all
  FROM DBA_CAPTURE_PREPARED_DATABASE;
  

Primary Key  Foreign Key  Unique         All Columns
Supplemental Supplemental Supplemental   Supplemental
Logging      Logging      Logging        Logging
------------ ------------ -------------- ------------
IMPLICIT     IMPLICIT     IMPLICIT       NO

Displaying the Queue and Rule Set of Each Synchronous Capture

You can display the following information about each synchronous capture in a database by running the query in this section:

• The synchronous capture name

• The name of the queue used by the synchronous capture

• The name of the positive rule set used by the synchronous capture

• The capture user for the synchronous capture

To display this general information about each synchronous capture in a database, run the following query:

COLUMN CAPTURE_NAME HEADING 'Synchronous|Capture Name' FORMAT A20
COLUMN QUEUE_NAME HEADING 'Synchronous|Capture Queue' FORMAT A20
COLUMN RULE_SET_NAME HEADING 'Positive Rule Set' FORMAT A20
COLUMN CAPTURE_USER HEADING 'Capture User' FORMAT A15

SELECT CAPTURE_NAME, QUEUE_NAME, RULE_SET_NAME, CAPTURE_USER
   FROM DBA_SYNC_CAPTURE;

Your output looks similar to the following:

Synchronous          Synchronous
Capture Name         Capture Queue        Positive Rule Set    Capture User
-------------------- -------------------- -------------------- ---------------
SYNC01_CAPTURE       STRM01_QUEUE         RULESET$_21          STRMADMIN
SYNC02_CAPTURE       STRM02_QUEUE         SYNC02_RULE_SET      HR

Displaying the Tables For Which Synchronous Capture Captures Changes

The DBA_SYNC_CAPTURE_TABLES view displays the tables whose DML changes are captured by any synchronous capture in the local database. The DBA_STREAMS_TABLE_RULES view has information about each synchronous capture name and the rules used by each synchronous capture. You can display the following information by running the query in this section:

• The name of each synchronous capture

• The name of each rule used by the synchronous capture

• If the rule is a subset rule, then the type of subsetting operation covered by the rule

• The owner of each table specified in each rule

• The name of each table specified in each rule

• Whether synchronous capture is enabled or disabled for the table. If the synchronous capture is enabled for a table, then it captures DML changes made to the table. If synchronous capture is not enabled for a table, then it does not capture DML changes made to the table.

To display this information, run the following query:

COLUMN STREAMS_NAME HEADING 'Synchronous|Capture Name' FORMAT A15
COLUMN RULE_NAME HEADING 'Rule Name' FORMAT A15
COLUMN SUBSETTING_OPERATION HEADING 'Subsetting|Operation' FORMAT A10
COLUMN TABLE_OWNER HEADING 'Table|Owner' FORMAT A10
COLUMN TABLE_NAME HEADING 'Table Name' FORMAT A15
COLUMN ENABLED HEADING 'Enabled?' FORMAT A8

SELECT r.STREAMS_NAME, 
       r.RULE_NAME, 
       r.SUBSETTING_OPERATION,
       t.TABLE_OWNER, 
       t.TABLE_NAME, 
       t.ENABLED
   FROM DBA_STREAMS_TABLE_RULES r,
        DBA_SYNC_CAPTURE_TABLES t
   WHERE r.STREAMS_TYPE = 'SYNC_CAPTURE' AND
         r.TABLE_OWNER  = t.TABLE_OWNER AND
         r.TABLE_NAME   = t.TABLE_NAME;

Your output looks similar to the following:

Synchronous                     Subsetting Table
Capture Name    Rule Name       Operation  Owner      Table Name      Enabled?
--------------- --------------- ---------- ---------- --------------- --------
SYNC01_CAPTURE  EMPLOYEES20                HR         EMPLOYEES       YES
SYNC02_CAPTURE  DEPARTMENTS24   DELETE     HR         DEPARTMENTS     YES
SYNC02_CAPTURE  DEPARTMENTS23   UPDATE     HR         DEPARTMENTS     YES
SYNC02_CAPTURE  DEPARTMENTS22   INSERT     HR         DEPARTMENTS     YES

This output indicates that synchronous capture sync01_capture captures DML changes made to the hr.employees table. This output also indicates that synchronous capture sync02_capture captures a subset of the changes to the hr.departments table.

If the ENABLED column shows NO for a table, then synchronous capture does not capture changes to the table. The ENABLED column shows NO when a table rule is added to a synchronous capture rule set by a procedure other than ADD_TABLE_RULES or ADD_SUBSET_RULES in the DBMS_STREAMS_ADM package. For example, if the ADD_RULE procedure in the DBMS_RULE_ADM package adds a table rule to a synchronous capture rule set, then the table appears when you query the DBA_SYNC_CAPTURE_TABLES view, but synchronous capture does not capture DML changes to the table. No results appear in the DBA_SYNC_CAPTURE_TABLES view for schema and global rules.