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Tuesday, 14 June 2011

What is lock table over flow ? How to resolve lock table overflow issue ?

This article answers the below queries ?

  • What is lock table overflow ?
  • How to identify lock table over flow issue ?
  • What is the parameter to be changed to increase lock table size in SAP ?
  • What is the reason for lock table overflow ?
  • How to resolve lock table overflow ?

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What is lock table overflow ?

SAP manages locks using lock table. The lock table contains all of the informaton related to locks like who is holding the lock and which locks are currently held etc. The size of the lock table can be specified by the SAP parameter enque/table_size. The size of the lock table limits the number of locks, lock owners and lock names. If this size is exceeded, then the lock table overflow occurs.

How to identify lock table overflow issue ?

In SM21 transaction log and ST22 dumps, if you find any error messages like LOCK_TABLE_OVERFLOW, Lock table overflow, Internal lock administration error it means there is a lock table overflow issue.


What is the parameter to be changed to increase lock table size in SAP ?

Parameter enque/table_size to be changed to increase or decrease lock table size using RZ10 transaction. Default value of this parameter is 32768. The min value that can be set is 4096 and max value is 102400. The unit for this parameter is KB.


As this is not dynamic parameter, for the new value to take effect, a system restart is required after modifying the parameter.

What is the reason for lock table overflow ?

A lock table overflow can occur due to

  • The lock table is configured too small (i.e value set to enque/table_size parameter is very low)
  • Due to improper design of application which sets a large number of locks
  • Number of enqueue worprocesses configured in a sap system are less and update is very slow/hanging due to which lots of locks are accumulated in lock table
  • Running a custom report with improper selection criteria (like very long time periods data pull) which sets so many locks & eventually lock table overflow occurs

 How to resolve lock table overflow ?

  • Increase the size of lock table i.e increase the parameter enque/table_size value using RZ10 transaction.
          To determine the optimal value for this parameter, you can check the maximum locks set so far in the history and the current number of locks set from SM12 -> Extras -> Statistics

  • Increase the number of enqueue workprocesses


  

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11 comments:

  1. Rakesh reddy28 December 2012 at 14:32

    Hi Durga prasad
    This blog is very good,freshers can easily understand the topics.you made it very clear.
    Please try to add more topics as much you can mainly on Java stack,Netweaver and Solman.

    Thank u for your great efforts for making this wonderful Blog :)

    ReplyDelete
  2. Anonymous9 January 2013 at 18:51

    Hi DurgaPrasad,

    Enque WP should be one per the Whole SAP System to my Knowledge.

    But you are saying that We can increase the Enque WP for LOCK_TABLE_OVERFLOW dump.

    Thanks, Venkat.

    ReplyDelete
  3. DurgaPrasad9 January 2013 at 21:37

    Hi Venkat,

    It is wrong assumption that only one enqueue wp will be there for whole sap system. Eventhough one enqueue workprocess is sufficient for an sap system, more than one enqueue workprocess can be defined for very large sap systems.

    Please goto RZ11 transaction and provide input as rdisp/wp_no_enq and check the min and max values for that parameter. We can configure upto 100 enqueue workprocesses for very large sap systems. Also go through documentation of this parameter in Rz11 to understand more.

    Hope I have clarified your query.


    ReplyDelete
  4. DurgaPrasad9 January 2013 at 21:38

    @Rakesh : Thanks for your nice comments. Sure, will try to post more on netweaver topics

    ReplyDelete
  5. Anonymous28 March 2013 at 21:36

    Hello DurgaPrasad,

    The SAP parameter "enque/table_size" must be set only on the application server that have ENQ Work Pprocess??

    So, The secondary application servers that no have ENQ Work Process wouldn't be set this parameter?? Is that right??

    Thanks in advance, Ivan

    ReplyDelete
  6. Anonymous3 April 2013 at 16:08

    can we increase the update work process ....????? so that the lock table over flow will not occur.

    ReplyDelete
  7. Anonymous30 July 2013 at 20:40

    Hi,

    What are the effects and results on the system, if lock table overflows..??

    ReplyDelete
  8. SAP BASIS with HANA Administration18 November 2015 at 14:40

    Hi durgaprasad,

    thanx for posting all this link

    If lock table is overflow,is there any solution other then increasing size of table

    ReplyDelete
  9. Anonymous2 February 2016 at 04:47

    Hi..., could Lock tale overflow issue cause data corruption? I ran larger data loading and faced Lock table overflow issue. My enqueue server was stopped. After restarting the enqueue services, the data loading went thru fine. But my application team found there were data error. I am trying to figure out was the data error happened because of lock table overflow or program?

    ReplyDelete
  10. Anonymous6 January 2018 at 14:10

    Hi, How many enq work process we can increase?

    ReplyDelete
  11. Santiagoemf21 August 2019 at 04:08

    Thanks, it helped me a lot. Hi from Mexico.

    ReplyDelete

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