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
.-IMMEDIATE-.
>>-CREATE BUFFERPOOL--bufferpool-name--+-----------+------------>
'-DEFERRED--'
.-ALL DBPARTITIONNUMS-----------------------------------.
>--+-------------------------------------------------------+---->
| .-,-----------------------. |
| V | |
'-DATABASE PARTITION GROUP----db-partition-group-name-+-'
.-SIZE--1000--AUTOMATIC----------------.
>--+--------------------------------------+--●------------------>
+-SIZE--number-of-pages----------------+
| .-1000------------. |
'-SIZE--+-----------------+--AUTOMATIC-'
'-number-of-pages-'
>--+-------------------+--●------------------------------------->
'-| except-clause |-'
.-NUMBLOCKPAGES 0------------------------------------------------.
>--+----------------------------------------------------------------+-->
'-NUMBLOCKPAGES--number-of-pages--+----------------------------+-'
'-BLOCKSIZE--number-of-pages-'
>--●--+--------------------------+--●--------------------------><
'-PAGESIZE--integer--+---+-'
'-K-'
except-clause
|--EXCEPT ON--+-MEMBER--+--------------------------------------->
'-MEMBERS-'
.-,-------------------------------------------------------------.
V |
>--(----member-number1--+--------------------+--SIZE--number-of-pages-+--)--|
'-TO--member-number2-'
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. 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; DB2® will
allocate the required memory 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
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 determined by the self-tuning memory manager (STMM).
Note that STMM enforces a minimum size for automatic buffer pools.
To determine the current size of buffer pools that are enabled for
self tuning, use the GET SNAPSHOT command and examine
the current size of the buffer pools (the value of 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, 16 384, or 32 768. 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 DB2 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