SESSION LOGS:
Information that reside in a session log:
- Allocation of system shared memory
- Execution of Pre-session commands/ Post-session commands
- Session Initialization
- Creation of SQL commands for reader/writer threads
- Start/End timings for target loading
- Error encountered during session
- Load summary of Reader/Writer/ DTM statistics
Other Information
- By default, the server generates log files based on the server code page.
Thread Identifier
Ex: CMN_1039
Reader and Writer thread codes have 3 digit and Transformation codes have 4 digits.
The number following a thread name indicate the following:
(a) Target load order group number
(b) Source pipeline number
(c) Partition number
(d) Aggregate/ Rank boundary number
Log File Codes:
Error Codes Description
BR - Related to reader process, including ERP, relational and flat file.
CMN - Related to database, memory allocation
DBGR - Related to debugger
EP- External Procedure
LM - Load Manager
TM - DTM
REP - Repository
WRT - Writer
Load Summary
(a) Inserted
(b) Updated
(c) Deleted
(d) Rejected
Statistics details
(a) Requested rows shows the no of rows the writer actually received for the specified operation
(b) Applied rows shows the number of rows the writer successfully applied to the target (Without Error)
(c) Rejected rows show the no of rows the writer could not apply to the target
(d) Affected rows shows the no of rows affected by the specified operation
Detailed transformation statistics
The server reports the following details for each transformation in the mapping
(a) Name of Transformation
(b) No of I/P rows and name of the Input source
(c) No of O/P rows and name of the output target
(d) No of rows dropped
Tracing Levels
Normal - Initialization and status information, Errors encountered, Transformation errors, rows skipped, summarize session details (Not at the level of individual rows)
Terse - Initialization information as well as error messages, and notification of rejected data
Verbose Init - Addition to normal tracing, Names of Index, Data files used and detailed transformation statistics.
Verbose Data - Addition to Verbose Init, Each row that passes in to mapping detailed transformation statistics.
NOTE
When you enter tracing level in the session property sheet, you override tracing levels configured for transformations in the mapping.
MULTIPLE SERVERS
With Power Center, we can register and run multiple servers against a local or global repository. Hence you can distribute the repository session load across available servers to improve overall performance. (You can use only one Power Mart server in a local repository)
Issues in Server Organization
- Moving target database into the appropriate server machine may improve efficiency
- All Sessions/Batches using data from other sessions/batches need to use the same server and be incorporated into the same batch.
- Server with different speed/sizes can be used for handling most complicated sessions.
Session/Batch Behavior
- By default, every session/batch run on its associated Informatica server. That is selected in property sheet.
- In batches, that contain sessions with various servers, the property goes to the servers, that’s of outer most batch.
Session Failures and Recovering Sessions
Two types of errors occurs in the server
- Non-Fatal
- Fatal
(a) Non-Fatal Errors
It is an error that does not force the session to stop on its first occurrence. Establish the error threshold in the session property sheet with the stop on option. When you enable this option, the server counts Non-Fatal errors that occur in the reader, writer and transformations.
Reader errors can include alignment errors while running a session in Unicode mode.
Writer errors can include key constraint violations, loading NULL into the NOT-NULL field and database errors.
Transformation errors can include conversion errors and any condition set up as an ERROR,. Such as NULL Input.
(b) Fatal Errors
This occurs when the server can not access the source, target or repository. This can include loss of connection or target database errors, such as lack of database space to load data.
If the session uses normalizer (or) sequence generator transformations, the server can not update the sequence values in the repository, and a fatal error occurs.
(c) Others
Usages of ABORT function in mapping logic, to abort a session when the server encounters a transformation error.
Stopping the server using pmcmd (or) Server Manager
Performing Recovery
- When the server starts a recovery session, it reads the OPB_SRVR_RECOVERY table and notes the rowid of the last row commited to the target database. The server then reads all sources again and starts processing from the next rowid.
- By default, perform recovery is disabled in setup. Hence it won’t make entries in OPB_SRVR_RECOVERY table.
- The recovery session moves through the states of normal session schedule, waiting to run, Initializing, running, completed and failed. If the initial recovery fails, you can run recovery as many times.
- The normal reject loading process can also be done in session recovery process.
- The performance of recovery might be low, if
o Mapping contain mapping variables
o Commit interval is high
Un recoverable Sessions
Under certain circumstances, when a session does not complete, you need to truncate the target and run the session from the beginning.
