CDC Guide for Linux, UNIX, and Windows

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CAPI_CONNECTION - UOWC Statement

The UOWC CAPI_CONNECTION statement specifies a named set of parameters that the Consumer API (CAPI) uses for the UOW Cleanser.

In the change stream for some data sources, changes from multiple UOWs are intermingled. The UOW Cleanser reconstructs the intermingled changes read from the change stream into complete UOWs in chronological order based on end time.

i5/OS, Linux, UNIX, Windows, and z/OS

DB2 for i5/OS CDC sources, Oracle CDC with LogMiner sources, and z/OS CDC sources

CAPI_CONNECTION - AS4J, CAPI_CONNECTION - LRAP, and CAPI_CONNECTION - ORCL

Yes, for CDC for the specified sources

CAPI_CONNECTION=([DLLTRACE=trace_id]
                 ,NAME=capi_connection_name
                [,TRACE=trace_name]
                 ,TYPE=(UOWC
                       ,CAPINAME=source_capi_name
                      [,BLKSIZE=block_size]
                      [,DATACLASS=data_class]
                      [,LARGEOPS=number_of_operations]
                      [,MEMCACHE={cache_size|1024}]
                      [,MONITORINT={minutes|5}]
                      [,RSTRADV=seconds]
                      [,SPACEPRI={primary_space|50}]
                      [,SPACETYP={BLK|TRK|CYL}]
                      [,SPILLKEEP=number_of_spill_files]
                      [,STORCLASS=storage_class]
                      [,TIMESTAMP={LOG|COMMIT}]
                      [,UNIT=unit]
                  )
)

DLLTRACE=trace_id

Optional. A user-defined name for the TRACE statement that activates internal DLL tracing for this CAPI.

Specify this parameter only at the direction of Informatica Global Customer Support.

NAME=capi_connection_name

Required. A unique user-defined name for this CAPI_CONNECTION statement.

Maximum length is eight alphanumeric characters.

TRACE=trace_name

Optional. A user-defined name for the TRACE statement that activates the common CAPI tracing.

Specify this parameter only at the direction of Informatica Global Customer Support.

TYPE=(UOWC, ... )

Required. The type of CAPI_CONNECTION statement. For the UOW Cleanser, this value must be UOWC.

CAPINAME=capi_name: Required. The value of the NAME parameter in the related source-specific CAPI_CONNECTION statement, which can be one of the following statement types:

AS4J CAPI_CONNECTION statement for DB2 for i5/OS sources
ORCL CAPI_CONNECTION statement for Oracle CDC with LogMiner sources
LRAP CAPI_CONNECTION statement for data sources on z/OS
BLKSIZE=block_size: Optional. The block size, in bytes, for the sequential UOW spill files that the UOW Cleanser creates when the memory cache cannot hold all changes for a UOW.

The following table shows valid values by CDC source type:

Data Source Type
Valid Values
Default Value

DB2 for i5/OS
A number from 8 through 32760
32760

Oracle
A number from 8 through 65535
32768

z/OS data sources
A number from 8 through 32760
18452
DATACLASS=data_class: Optional. On z/OS, the SMS data class that the UOW Cleanser uses when allocating the sequential UOW spill files. If you do not specify this parameter, the SMS ACS routines can assign the data class.
LARGEOPS=number of operations: Optional. Overrides the default value that PowerExchange uses to identify transactions as large transactions for reporting purposes. Enter the number of DML operations (inserts, updates, and deletes), in thousands, that a transaction must contain to be considered a large transaction.

PowerExchange issues status messages for large transactions that meet this criteria. If PowerExchange issues too many messages, you can increase this value to limit the number of messages.

Valid values are 1 through 2147483 (1000 through 2,147,483,000 operations). The default value is one half of the MEMCACHE parameter value rounded up to the nearest thousand. Based on the default MEMCACHE value of 1024 KB, the default LARGEOPS value is 1000 (1,000,000 operations).
MEMCACHE={cache_size| 1024 }: Optional. The maximum memory cache size, in kilobytes, that PowerExchange allocates to reconstruct complete UOWs.

Enter a number from 0 through 2147483647. Default is 1024 KB. If you enter 0, the memory cache size is limited only by the available memory on the system.

For each extraction session, PowerExchange keeps all changes for each UOW in the memory cache until it processes the end-UOW record. PowerExchange incrementally allocates memory cache up to the limit that this parameter specifies. If the memory cache is too small to hold all of the changes in a UOW, PowerExchange spills the changes to a sequential files on disk, called UOW spill files.

Each UOW spill file contains one UOW. A UOW might require multiple UOW spill files to hold all of the changes for that UOW. If the change stream contains multiple large UOWs and the memory cache is insufficient, PowerExchange might create numerous UOW spill files.

PowerExchange processes the change stream more efficiently if it does not need to use UOW spill files. A large number of UOW spill files can degrade extraction performance and cause disk space shortages.

If the change stream contains small UOWs, the default value might be sufficient. However, Informatica recommends that you specify a larger value because the default value is often too small.

The location in which PowerExchange allocates the UOW spill files varies by operating system, as follows:

For i5/OS, PowerExchange uses CRTPF command to create a physical file for UOW spill files.
PowerExchange names the UOW spill files using the C/C++ tmpnam() function.

For Linux and UNIX, PowerExchange uses the current directory by default for UOW spill files. To use a different directory, specify the TMPDIR environment variable.
PowerExchange names the UOW spill file names using the prefix "dtlq" and the operating system function tempnam.

The UOW spill files are temporary files that are deleted when PowerExchange closes them. These files are not visible in the directory while they are open.

For Windows, PowerExchange uses the current directory by default for UOW spill files. To use a different directory, specify the TMP environment variable.
PowerExchange names the UOW spill file using the prefix "dtlq" and the Windows _tempnam function.

For z/OS, PowerExchange uses dynamic allocation to allocate temporary data sets for the UOW spill files. Generally, SMS controls the location of temporary data sets. If you do not use SMS to control temporary data sets, the UNIT parameter controls the location for the UOW spill files.
Because PowerExchange allocates temporary data sets for the UOW spill files, z/OS assigns these files system-generated data set names, which begin with SYSyyddd.Thhmmss.RA000.jobname.

PowerExchange allocates the cache size for each extraction operation. If you use a large MEMCACHE value and run many concurrent extraction sessions, memory constraints can occur.
MONITORINT=minutes: Optional. The time interval, in minutes, at which PowerExchange checks transaction activity for long outstanding transactions and large transactions. A long outstanding transaction is one that remains active for two monitoring intervals, and a large transaction is one that meets the LARGEOPS criteria. When this interval elapses, PowerExchange issues messages that identify the large transactions and long outstanding transactions and report their processing activity. PowerExchange also issues messages that identify the current position in the change stream. Valid values are 0 through 720. A value of 0 disables monitoring. Default is 5.
RSTRADV=seconds: The time interval, in seconds, that PowerExchange waits before advancing restart and sequence tokens for a registered data source during periods when UOWs do not include any changes of interest for the data source. When the wait interval expires, PowerExchange returns the next committed "empty UOW," which includes only updated restart information.

Enter a number from 0 through 86400. No default is provided.

PowerExchange resets the wait interval to 0 when one of the following events occur:
PowerExchange completes processing a UOW that includes changes of interest.
PowerExchange returns an empty UOW because the wait interval expired without PowerExchange receiving any changes of interest.

For example, if you specify 5, PowerExchange waits five seconds after it completes processing the last UOW or after the previous wait interval expires. Then PowerExchange returns the next committed empty UOW that includes the updated restart information and resets the wait interval to 0.

If you do not specify RSTRADV, PowerExchange does not advance restart and sequence tokens for a registered source during periods when PowerExchange receives no changes of interest. When PowerExchange warm starts, it reads all changes, including those not of interest for CDC, from the restart point.

For DB2 for i5/OS sources, Informatica recommends that you use this parameter if the change records that PowerExchange reads from i5/OS journal receivers are created under commitment control. If the change records are created without commitment control, do not specify this parameter.

A value of 0 can degrade performance. In addition to the UOWs that contain changes for registered sources of interest, PowerExchange returns an empty UOW for every UOW that does not contain changes for the registered sources of interest.
SPACEPRI={primary_space| 50 }: Optional. On z/OS, the amount of primary space that the UOW Cleanser uses for allocating UOW spill files. The SPACETYP parameter indicates the type of space units.

Enter a number from 1 through 16777215. Default is 50 blocks.

The UOW Cleanser does not use secondary space. Instead, when a spill file becomes full, the UOW Cleanser allocates another spill file of the same size.

SMS ACS routines can override the UOW spill file size.

On i5/OS, the UOW Cleanser allocates UOW spill files as physical files with SIZE(*NOMAX), which means that the maximum spill file size is controlled by the system maximum file size. On Linux, UNIX, and Windows, PowerExchange allocates UOW spill files as temporary files that are 2 GB in size.

Data Source Type	Valid Values	Default Value
DB2 for i5/OS	A number from 8 through 32760	32760
Oracle	A number from 8 through 65535	32768
z/OS data sources	A number from 8 through 32760	18452

SPACETYP={ BLK |TRK|CYL}: Optional. On z/OS, the type of units in which the primary space for UOW Cleanser allocation of UOW spill files is expressed.

Options are:

BLK
. Blocks.
CYL
. Cylinders.
TRK
. Tracks.

Default is BLK.
SPILLKEEP=number_of_spill_files: Optional. The number of spill files that the UOW Cleanser retains for re-assignment. The UOW Cleanser retains spill files instead of deallocating them so that the files are available to be reassigned to new transactions. This feature is intended to prevent excessive file deallocation and allocation activity.

Valid values are 0 through 999. On z/OS and i5/OS, the default is 3. On Linux, UNIX, and Windows, the default is 0.
STORCLASS=storage_class: Optional. On z/OS, the SMS storage class name that the UOW Cleanser uses to allocate UOW spill files.
TIMESTAMP={ LOG |COMMIT}: Optional. The type of timestamp that PowerExchange records in the generated DTL__CAPXTIMESTAMP column of each change record for a transaction. Specify this parameter only if you want to display the commit timestamp instead of the timestamp from the source logs or data sets.

Options are:

LOG
. The timestamp of a change on the source database, as recorded by the DBMS in the source database logs or data sets near the time when the change is made. For more information, see DTL__CAPXTIMESTAMP Time Stamps.
COMMIT
. The timestamp of the transaction commit on the source database. Specify this option if you use the timestamp to calculate latency.

Default is LOG.
UNIT=unit: Optional. On z/OS, the generic or esoteric unit name that the UOW Cleanser uses to allocate UOW spill files.

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Table of Contents

CDC Guide for Linux, UNIX, and Windows

CDC Guide for Linux, UNIX, and Windows

CAPI_CONNECTION - UOWC Statement

CAPI_CONNECTION - UOWC Statement