CREATE BUFFERPOOL statement

The CREATE BUFFERPOOL statement defines a buffer pool at the current server. Buffer pools are defined on members which can access data partitions.

Invocation

This statement can be embedded in an application program or issued interactively. It is an executable statement that can be dynamically prepared only if DYNAMICRULES run behavior is in effect for the package (SQLSTATE 42509).

Authorization

The privileges held by the authorization ID of the statement must include SYSCTRL or SYSADM authority.

Syntax

Read syntax diagramSkip visual syntax diagramCREATE BUFFERPOOLbufferpool-name IMMEDIATEDEFERREDALL DBPARTITIONNUMSDATABASE PARTITION GROUP,db-partition-group-nameSIZE1000AUTOMATICSIZEnumber-of-pagesSIZE1000number-of-pagesAUTOMATIC●except-clause●NUMBLOCKPAGES 0NUMBLOCKPAGESnumber-of-pagesBLOCKSIZEnumber-of-pages●PAGESIZEintegerK●
except-clause
Read syntax diagramSkip visual syntax diagramEXCEPT ONMEMBERMEMBERS( ,member-number1TOmember-number2SIZEnumber-of-pages )

Description

bufferpool-name
Names the buffer pool. This is a one-part name. It is an SQL identifier (either ordinary or delimited). The bufferpool-name must not identify a buffer pool that already exists in the catalog (SQLSTATE 42710). The bufferpool-name must not begin with the characters 'SYS' (SQLSTATE 42939).
IMMEDIATE or DEFERRED
Indicates whether or not the buffer pool will be created immediately.
IMMEDIATE
The buffer pool will be created immediately after the CREATE BUFFERPOOL statement is committed. If there is not enough reserved space in the database shared memory to allocate the new buffer pool (SQLSTATE 01657) the statement is executed as DEFERRED.
DEFERRED
The buffer pool will be created when the database is deactivated (all applications need to be disconnected from the database). Reserved memory space is not needed; required memory will be allocated from the system.
ALL DBPARTITIONNUMS or DATABASE PARTITION GROUP
Identifies the members on which the buffer pool is to be defined. The default is ALL DBPARTITIONNUMS.
ALL DBPARTITIONNUMS
This buffer pool will be created on all members which can access all data partitions in the database.
DATABASE PARTITION GROUP db-partition-group-name
Identifies the database partition group or groups to which the buffer pool definition applies. The buffer pool will be created only on members in the specified database partition groups. Each database partition group must exist in the database (SQLSTATE 42704).
SIZE
Specifies the size of the buffer pool. This size will be the default size for all members on which the buffer pool exists. The default is 1000 pages.
number-of-pages
The number of pages for the new buffer pool. The minimum number of pages is 2 and the maximum is architecture-dependent (SQLSTATE 42615).
AUTOMATIC
Enables self tuning for this buffer pool. The database manager adjusts the size of the buffer pool in response to workload requirements. The implicit or explicit number of pages that are specified is used as the initial size of the buffer pool. On subsequent database activations, the buffer pool size is based on the last tuning value that is determined by the self-tuning memory manager (STMM). The STMM enforces a minimum size for automatic buffer pools, which is the minimum of the current size and 5000 pages. To determine the current size of buffer pools that are enabled for self tuning, use the MON_GET_BUFFERPOOL routine and examine the current size of the buffer pools. The size of the buffer pool is found in the bp_cur_buffsz monitor element.
NUMBLOCKPAGES number-of-pages
Specifies the number of pages that should exist in the block-based area. The number of pages must not be greater than 98 percent of the number of pages for the buffer pool (SQLSTATE 54052). Specifying the value 0 disables block I/O. The actual value of NUMBLOCKPAGES used will be a multiple of BLOCKSIZE.

NUMBLOCKPAGES is not supported in a Db2® pureScale® environment (SQLSTATE 56038).

BLOCKSIZE number-of-pages
Specifies the number of pages in a block. The block size must be a value between 2 and 256 (SQLSTATE 54053). The default value is 32.

BLOCKSIZE is not supported in a Db2 pureScale environment (SQLSTATE 56038).

EXCEPT ON MEMBER or EXCEPT ON MEMBERS
Specifies the member or members for which the size of the buffer pool will be different than the default specified for the database partition group to which the member has access. If this clause is not specified, all members that can access the data partitions in the specified database partition group will have the same size as specified for this buffer pool.
member-number1
Specifies a member number for a member that has access to a data partition for which the buffer pool is created (SQLSTATE 42729).
TO member-number2
Specifies a range of member numbers. The value of member-number2 must be greater than or equal to the value of member-number1 (SQLSTATE 428A9). Each member identified by the member number range inclusive must have access to the data partition for which the buffer pool is created (SQLSTATE 428A9).
SIZE number-of-pages
The size of the buffer pool specified as the number of pages. The minimum number of pages is 2 and the maximum is architecture-dependent (SQLSTATE 42615).
PAGESIZE integer [K]
Defines the size of pages used for the buffer pool. The valid values for integer without the suffix K are 4096, 8192, 16384, or 32768. The valid values for integer with the suffix K are 4, 8, 16, or 32. Any number of spaces is allowed between integer and K, including no space. If the page size is not one of these values, an error is returned (SQLSTATE 428DE).

The default value is provided by the pagesize database configuration parameter, which is set when the database is created.

Notes

  • If the buffer pool is created using the DEFERRED option, any table space created in this buffer pool will use a small system buffer pool of the same page size, until next database activation. The database has to be restarted for the buffer pool to become active and for table space assignments to the new buffer pool to take effect. The default option is IMMEDIATE.
  • There should be enough real memory on the machine for the total of all the buffer pools, as well as for the rest of the database manager and application requirements. If the database is unable to obtain memory for the regular buffer pools, it will attempt to start with small system buffer pools, one for each page size (4K, 8K, 16K and 32K). In this situation, a warning will be returned to the user (SQLSTATE 01626), and the pages from all table spaces will use the system buffer pools.
  • Syntax alternatives: The following syntax alternatives are supported for compatibility with previous versions of Db2 and with other database products. These alternatives are non-standard and should not be used.
    • NODEGROUP can be specified in place of DATABASE PARTITION GROUP
    • DBPARTITIONNUM or NODE can be specified in place of MEMBER, except when the DB2_ENFORCE_MEMBER_SYNTAX registry variable is set to ON
    • DBPARTITIONNUMS or NODES can be specified in place of MEMBERS, except when the DB2_ENFORCE_MEMBER_SYNTAX registry variable is set to ON