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Version

All the versions of Altibase

 

Cause

For ALTIBASE memory tablespaces, the sum of all memory tablespaces cannot exceed MEM_MAX_DB_SIZE in $ALTIBASE_HOME/conf/altibase.properties. This error message occurs because all space is exhausted.

 

What is MEM_MAX_DB_SIZE?

  • This refers to the maximum amount of memory that can be used as a memory tablespace (memory table or memory data) stored in physical memory.

  • Constraints on the total usage of all memory tablespaces combined.

  • This is not the maximum size that each of the memory tablespaces can use.

  • The size of the index created on the memory table is not included.

  • It also includes historical data that occurs when performing change transactions.

  • When a change transaction is performed, past data is retained until the transaction is terminated (MVCC technique). In the case of a memory table, a replica of the record is created in the memory table.

  • If the maximum value is not specified when creating a memory tablespace, it is automatically expanded by the value set for MEM_MAX_DB_SIZE.

 

How to query memory usage

When ALLOC_SIZE reaches MEM_MAX_DB_SIZE as a result of the above inquiry, 'Too many pages are allocated' error occurs.

 

Solution

To prevent the following error from occurring, the MEM_MAX_DB_SIZE property value must be increased in $ALTIBASE_HOME/conf/altibase.properties.

If this value is increased, Altibase DB Size can be increased up to this size. After modifying the properties, you must restart Altibase to apply it.

After taking the action, it is necessary to take action by checking for some reason the increase in memory tablespace usage and whether there has been a query or mass change of the usage of each table.

 

How to change

  1. Stop the Altibase server

    $ server stop

     

     

  2. Change the altibase.properties file

    Save after changing MEM_MAX_DB_SIZE in the Altibase server properties file ($ALTIBASE_HOME/conf/altibase.properties).

    $ vi $ALTIBASE_HOME/conf/altibase.properties
    MEM_MAX_DB_SIZE        = 2G # MEM_MAX_DB_SIZE

     

     

  3. Start the Altibase server

    $ server start


Note/Consideration

Disk space

Memory tablespaces store two sets of 'memory checkpoint image files' on disk for backup purposes. So, it requires twice as much disk space as the memory data usage.

If MEM_MAX_DB_SIZE large is set, disk usage will also increase, so make sure to free up disk space before changing MEM_MAX_DB_SIZE.

Ex) If MEM_MAX_DB_SIZE is 60G, 120G of disk space is required.

 

User environment setting (Linux/Unix)

ulimit -a must be executed to make sure that the settings below are set to the maximum values allowed by the OS.

max memory size
virtual memory


Kernel parameter (AIX, HP-UX)

 

For AIX, check if data, rss, fsize, etc. are set to -1 in the /etc/security/limits file.
For HP, check that the maxdsiz_64bit value is set large enough via kctune. Even if the maxdsiz_64bit value is less than the MEM_MAX_DB_SIZE value of the ALTIBASE property, a 'Too many pages are allocated' error may occur. Therefore, the root account must be set higher than MEM_MAX_DB_SIZE of the ALTIBASE property.
Linux and SunOS are not applicable.

 

Reference

What is MEM_MAX_DB_SIZE?


 

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