Add a New Buffer Pool

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Add a New Buffer Pool

Add a New Buffer Pool:
 
|-- -b-- -g--size--+-------------+--+-------------+------------->
                   '- -n--number-'  '- -r--number-'
 
>--+-----------------+--+-----------------+---------------------|
   '- -x--percentage-'  '- -m--percentage-'

Element	Purpose	Key Considerations
-b	Creates a new buffer pool	Additional Information: You can add a new buffer pool while the database server is running. For more information on buffer pools, see the description of the configuration parameter BUFFERPOOL and the information on buffer pools in the IBM Informix Administrator's Guide.
-g size	Specifies the size in kilobytes of the buffer pages to create	Additional Information: Each dbspace you create with a non-default page size must have a corresponding buffer pool with the corresponding page size. If you create a dbspace with a page size that has no buffer pool, the system will automatically create a buffer pool using the fields in the default line of the BUFFERPOOL parameter. Restrictions: The size of the buffer pages must be between 2 and 16 kilobytes and it must be a multiple of the default page size.
-m percent	Specifies the percentage of modified pages in the LRU queues at which page cleaning is no longer mandatory	Additional Information: Fractional values are allowed. If you do not specify this option, the percentage used is the value of the lru_min_dirty field as set in the default line of the BUFFERPOOL configuration parameter. For the range of values , see The lru_min_dirty Field.
-n number	Specifies the number of buffers in the buffer pool	Additional Information: If you do not specify this option, the number used is the value of buffers as set in the default line of the BUFFERPOOL configuration parameter. For the range of values , see The buffers Field.
-r number	Specifies the number of LRU (least-recently-used) queues in the shared-memory buffer pool	Additional Information: If you do not include this option, the number of LRU queues allocated is equal to the value of lrus as set in the default line of the BUFFERPOOL configuration parameter. For the range of values, see The lrus Field.
-x percent	Specifies the default percentage of modified pages in the LRU queues at which the queue is cleaned	Additional Information: Fractional values are allowed. If you do not specify this option, the percentage used is the value of lru_max_dirty as set in the default line of the BUFFERPOOL configuration parameter. For the range of values , see The lru_max_dirty Field.

Create a buffer pool that corresponds to the page size of the dbspace. It is recommended that you do this before you create the dbspace. You cannot reduce or increase the number of buffers in an existing buffer pool while the database server is running. You also cannot drop a buffer pool while the database server is running. You can, however, add new buffer pools with a new size while the database server is running.

Buffer pools added with the onparams utility are put into virtual memory, not into resident memory. Upon restart, buffer pool entries will go into resident memory depending on the amount of memory that is available.

When you add a new buffer pool with the onparams utility or when you add a dbspace with a different page size (with the onspaces utility), the settings for the BUFFERPOOL configuration parameter in the ONCONFIG file are rewritten to reflect the new entry.