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IBM DB2 Analytics Accelerator for z/OS Version 5.1.0 maintenance level PTF-3: Release Notes

Release notes


Abstract

This document describes enhancements and fixes in IBM DB2 Analytics Accelerator for z/OS Version 5.1.0, maintenance level PTF-3

Content

We recommend an upgrade of the accelerator server component to this V5.1.0 PTF-3 for customers at product level V5.1.0 GA or V5.1.0 PTF-1 (UI35012, which was set PE). Customer who already have installed V5.1.0 PTF-2 are not affected.

With V5.1.0. GA and V5.1.0. PTF-1, a new way of data organization was introduced. The new organization has the potential to speed up the insertion of small chunks of data, which are typical for incremental updates. In rare situations, with huge table sizes, this new way of organizing data might lead to different query results returned by DB2 for z/OS and the accelerator. You can avoid this problem by switching back to the former way of data organization.

After an installation of V5.1.0 PTF-3, the former method of data organization is re-activated. If the switch back to the former data organization fails, the following message is written to the z/OS system log (SYSLOG) of the LPAR in which the DB2 subsystem or group is located:
DSNX881I - <SSID> W 2004 ... Not all zone map records are consistent with the expected layout
For further information regarding the structure of DSNX881I messages see:

Structure of DSNX881I Messages.

This is a temporary fix. The problem will be finally fixed with an upcoming release of the Netezza Platform Software (NPS). This NPS release will be certified for use with IBM DB2 Analytics Accelerator for z/OS.
Important: To make sure that all inconsistent data is removed from the accelerator, reload the potentially affected tables as decribed here:
How to identify tables that should be reloaded after an installation of V5.1.0 PTF-3

What's new

Please find information about new functions here.



Solved problems

  1. Snippet-Processing Units (SPUs) running out of resources
    Affected users
    All users of IBM DB2 Analytics Accelerator for z/OS
    Problem description
    Accelerator goes offline
    Problem summary
    This problem occurs if queries that are routed to an accelerator contain numerous recursive REPLACE() calls.
    Problem conclusion
    The problem has been fixed.
  2. Accelerator-shadow tables become inconsistent with empty tables in DB2 for z/OS
    Affected users
    All users of IBM DB2 Analytics Accelerator for z/OS
    Problem description
    An affected accelerator-shadow table contains more rows than the DB2 table.
    Problem summary
    This problem occurs during a full table reload, when you reload a segmented table or all partitions of a partitioned table.
    1. A DB2 for z/OS table contains data.
    2. A corresponding accelerator-shadow table exists and you have loaded it.
    3. All data is deleted from the table in DB2 for z/OS.
    4. The now empty table is reloaded on the accelerator. At this point, the DB2 for z/OS is empty, but the accelerator-shadow table might still contain the data loaded in step 2.
    Problem conclusion
    This PTF fixes the problem described in the following tech note: Data inconsistencies between accelerator-shadow tables and empty DB2 for z/OS tables

Migration recommendations and considerations

For recommendations and considerations concerning migration to IBM DB2 Analytics Accelerator for z/OS Version 5.1.0 read here.


Known issues

  1. IBM Netezza Analytics
    For known issues with the IBM Netezza Analytics stored procedure package in IBM DB2 Analytics Accelerator for z/OS Version 5.1.0, see:

    Known issues with IBM Netezza Analytics for System z for IBM DB2 Analytics Accelerator for z/OS Version 5.1.0

  2. Encryption of Data in Motion
    For known issues with the network traffic encryption feature (encryption of data in motion) in IBM DB2 Analytics Accelerator for z/OS Version 5.1.0, see:

    Known Issues with Encryption of Data in Motion in IBM DB2 Analytics Accelerator for z/OS Version 5.1.0

  3. Transfer of software update packages from IBM DB2 Analytics Accelerator Studio not possible
    Summary
    IBM Analytics Accelerator Studio does not allow users to transfer packages. A message hints at the fact that a newer version is already installed on the server. If the locale in the IBM Analytics Accelerator Data Studio is set to a value different from English or German, the transfer of software update packages might be blocked in rare cases.
    Solution or workaround
    The problem has been fixed with the stored procedures of version 5.1.0 PTF-1. If you run the software transfer with a previous version of the stored procedures, use the following workaround:
    1. Use US English as the locale for IBM DB2 Analytics Accelerator Studio.
    2. On a Windows system, add '-nl en_US' (without the quotes) to the start command that you find in the properties of the shortcut that launches the application ("Target" field on "Shortcut" tab).

      On a Linux system, open the eclipse.ini file and add the following line:

      -Duser.language=en -Duser.country=US

    3. Save and close the file. Then start the application.
  4. If the system utilization is very high, the accelerator might restart automatically to recover from the overload situation
    Summary
    The accelerator goes online again after the recovery. Processes that were ended prematurely by the restart, such as load jobs or queries, must be restarted.
    Solution or workaround
    1. Check the system utilization.
    2. Adjust the system utilization as needed.
    3. Retry failed operations and continue.
  5. Load operations stall if the system utilization is very high
    Summary
    Occasionally, load jobs might end abnormally if the system utilization is very high.
    Solution or workaround
    Cancel and restart the load operation.
  6. The execution of an INSERT INTO ... SELECT ... FROM statement in an in-database transformation job might fail
    Summary
    In rare situations, INSERT INTO ... SELECT ... FROM statements in in-database transformation jobs can fail if the system utilization is very high and many processes are run in parallel.
    Solution or workaround
    This is an indication that the system limits were reached. Check the system utilization and adjust it to the capacity of the system.
  7. Incremental update processing might stop and restart if the system utilization is very high (many parallel load and query operations). This is indicated by according console messages
    Summary
    If the system utilization is very high, with many processes running in parallel, the processing of incremental updates might stop. Processing resumes after some time and stalled operations are recovered automatically. If "continuous incremental updates" are enabled, tables that are being loaded at the time of the interruption go into the "suspended" state. You must reload such tables to get them back into the incremental update processing queue.
    Solution or workaround
    This is an indication that the system limits were reached. Check the system utilization and adjust it to the capacity of the system.
  8. High system utilization causes slower performance of IBM DB2 Analytics Accelerator tasks
    Summary
    Maintenance tasks might take longer than expected if the system utilization is high.
    Solution or workaround
    If the problem persists, restart the Netezza Platform Software (NPS) from the IBM DB2 Analytics Accelerator Console.
  9. Queries might fail if system utilization is high
    Summary
    A high system utilization might cause queries to fail occasionally with errors, such as ‘NZ IO error‘ or ‘SQL code = -904 00E7000E Bad data’ .
    Solution or workaround
    The system continues to operate. Subsequent queries succeed.
  10. A reload of a table set with many tables fails
    Summary
    A reload of a table set with thousands of tables might fail sporadically.
    Solution or workaround
    Split the table sets to be reloaded into smaller units and retry the operation.
  11. Load operation aborts with SIGABEND if the system utilization is very high
    Summary
    Occasionally, a load operation might end abnormally if the system utilization is very high.
    Solution or workaround
    Restart the load operation.
  12. Misleading warnings of type 'DSNX881I  -DI11 2001 W [...] SQL statement with task ID xxxxxxxx is running for more than xxxxxx seconds'
    Summary
    Under rare circumstances, a query might be continually reported as long-running, even though it was ended by a network outage or by a connection closure through the client application. These messages do not indicate that query processing is impacted in any way. The system stays operational and subsequent queries will run as expected.
    Solution or workaround
    The continual reporting of long-running tasks in DSNX88I messages stops after a restart of the accelerator. You can restart an accelerator from the IBM DB2 Analytics Accelerator Console.
  13. Insertion of integer and decimal values causes failure of IDT jobs
    Summary
    The insertion of integer and decimal values by an INSERT INTO ... VALUES statement might cause a failure of in-database transformation (IDT) jobs.

    For example, the following statement failed during tests:
    CREATE TABLE T1 (CDEC51 DECIMAL(5,1)) IN ACCELERATOR XYZ;
    INSERT INTO T1(CDEC51) VALUES(77247.04-69993);

    Symptoms: SQL codes like the following are returned:

    SQLCODE = -802, SQLSTATE = 22003, DATA EXCEPTION FROM IBM DB2 Analytics Accelerator TOKENS OVERFLOW ACCELERATOR NUMERIC DATA...

    Solution or workaround
    Use only decimal values instead of a mixture of integer and decimal values. The following statement, for example, will be successful:

    INSERT INTO T1(CDEC51) VALUES(77247.04-69993.0)

  14. Tables cannot be added if their names contain special characters, such as tabs and blanks
    Summary
    Tables cannot be added if their names contain special characters, such as tabs and blanks.
    Solution or workaround
    Fix will be delivered in a later release.
  15. Large number of accelerator-shadow tables might extend time needed to activate incremental updates
    Summary
    If there is a large number of tables on an accelerator, that is, more than 30000 the activation of incremental updates for these tables might take longer. In this context, it does not matter whether the tables have already been enabled. The extra time needed is relevant if the number of table activations in one request exceeds 10 because this will lead to a premature end of the operation, which in turn leads to an automatic disablement of incremental updates for those tables. You must re-enable and reload such tables.
    Solution or workaround
    Reduce the number of tables that are activated in a single batch job to less than ten (<10).
  16. If the system utilization is high, load operations might fail with a message "Failed to start child transaction in session " -LocksharedObjectWait: LockAcquire failed".
    Summary
    Under a high system load, load operations might fail with a message "Failed to start child transaction in session " -LocksharedObjectWait: LockAcquire failed".
    Solution or workaround
    Retry the load operation.

How to identify tables which should be reloaded after an installation of V5.1.0 PTF-3 (only if product level is "V5.1.0 GA" or "V5.1.0 PTF-1", without hot fix UI37271)

STEP 1: Identify the tables which could be affected
  • Use the sample code (for a stored procedure) in the following technote:

    How to store information about accelerated tables in a DB2 for z/OS table

    to retrieve information about your accelerator-shadow tables. This information will be stored in a temporary DB2 table.

  • Run a simple SQL query against the replicationStatus and the lastLoadTimestamp columns of this temporary table to identify tables that must be reloaded. Follow the diagram at the end of this note to dertermine whether a table must be reloaded.

STEP 2: For all identified tables, disable query acceleration. For more information, see Disabling query acceleration for tables

STEP 3: Install V5.1.0 PTF-3.

STEP 4: Automatic conversion
  • Immediately after the upgrade to V5.1.0 PTF-3, an automatic conversion of data structures takes place.
  • Depending on the total amount of data to be converted, this might take more than 1 hour, during which the Netezza Platform Software (NPS) will be in the "Initializing" state. That is, the NPS cannot process requests.
STEP 5: Reloading tables
Within the first hour after installation of the new accelerator server code, you might see a "DSNX881I - W 2004 ... Not all zone map records are consistent with the expected layout." message in the SYSLOG, which reports conversion failures. This is normal if the amount of data to be converted is high. The conversion failures are caused by a timeout mechanism. Check the SYSLOG one hour after the installation of the accelerator server. If you see zero or at most one DSNX88I-2004 message, the conversion has finished successfully and you can start with the full-table reload of the identified tables. If you see more than one DSNX88I-2004 message, check the SYSLOG again after 7 hours. If further messages show up, you might have a real conversion problem. In this case, contact IBM support.
STEP 6: Enable query acceleration after a full table reload. For more information, see Enabling tables for query acceleration
Click on the image to enlarge it
Diagram to identify affected tables

Support for DB2 12 for z/OS

Please find known issues here.

Document information

More support for: DB2 Analytics Accelerator for z/OS

Software version: 5.1.0

Operating system(s): z/OS

Reference #: 7048942

Modified date: 19 September 2017


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