DB2 Version 9.7 for Linux, UNIX, and Windows

MON_GET_BUFFERPOOL table function - Get buffer pool metrics

The MON_GET_BUFFERPOOL table function returns monitor metrics for one or more buffer pools.

Syntax


>>-MON_GET_BUFFERPOOL--(--bp_name--,--member--)----------------><

The schema is SYSPROC.

Table function parameters

bp_name: An input argument of type VARCHAR(128) that specifies a valid buffer pool name in the currently connected database when calling this function. If the argument is null or an empty string, metrics are retrieved for all buffer pools in the database.
member: An input argument of type INTEGER that specifies a valid member in the same instance as the currently connected database when calling this function. Specify -1 for the current database member, or -2 for all database members. If the null value is specified, -1 is set implicitly.

Authorization

EXECUTE privilege on the MON_GET_BUFFERPOOL function.

Example

Compute the buffer pool hit ratio.

WITH BPMETRICS AS (
    SELECT bp_name,
           pool_data_l_reads + pool_temp_data_l_reads +
           pool_index_l_reads + pool_temp_index_l_reads +
           pool_xda_l_reads + pool_temp_xda_l_reads as logical_reads,
           pool_data_p_reads + pool_temp_data_p_reads +
           pool_index_p_reads + pool_temp_index_p_reads +
           pool_xda_p_reads + pool_temp_xda_p_reads as physical_reads,
           member
    FROM TABLE(MON_GET_BUFFERPOOL('',-2)) AS METRICS)
   SELECT
    VARCHAR(bp_name,20) AS bp_name,
    logical_reads,
    physical_reads,
    CASE WHEN logical_reads > 0
     THEN DEC((1 - (FLOAT(physical_reads) / FLOAT(logical_reads))) * 100,5,2)
     ELSE NULL
    END AS HIT_RATIO,
    member
   FROM BPMETRICS;

The following example is a sample output from this query.

BP_NAME          LOGICAL_READS    PHYSICAL_READS HIT_RATIO MEMBER
---------------- ---------------- -------------- --------- ---------
IBMDEFAULTBP                  619            385     37.80         0
IBMSYSTEMBP4K                   0              0         -         0
IBMSYSTEMBP8K                   0              0         -         0
IBMSYSTEMBP16K                  0              0         -         0
IBMSYSTEMBP32K                  0              0         -         0

  5 record(s) selected.

Output for query (continued).

... HIT_RATIO MEMBER
... --------- ------
...     37.80      0
...         -      0
...         -      0
...         -      0
...         -      0

Usage notes

The MON_GET_BUFFERPOOL table function returns one row of data per database buffer pool and per database member. No aggregation across database members is performed. However, aggregation can be achieved through SQL queries as shown in the example.

Metrics collected by this function are controlled at the database level using the mon_obj_metrics configuration parameter. By default, metrics collection is enabled.

Information returned

Table 1. Information returned for MON_GET_BUFFERPOOL
Column Name	Data Type	Description or corresponding monitor element
BP_NAME	VARCHAR(128)	bp_name - Buffer pool name
MEMBER	SMALLINT	member- Database member
AUTOMATIC	SMALLINT	automatic - Buffer pool automatic
DIRECT_READS	BIGINT	direct_reads - Direct reads from database
DIRECT_READ_REQS	BIGINT	direct_read_reqs - Direct read requests
DIRECT_WRITES	BIGINT	direct_writes - Direct writes to database
DIRECT_WRITE_REQS	BIGINT	direct_write_reqs - Direct write requests
POOL_DATA_L_READS	BIGINT	pool_data_l_reads - Buffer pool data logical reads
POOL_TEMP_DATA_L_READS	BIGINT	pool_temp_data_l_reads - Buffer pool temporary data logical reads
POOL_XDA_L_READS	BIGINT	pool_xda_l_reads - Buffer pool XDA data logical reads
POOL_TEMP_XDA_L_READS	BIGINT	pool_temp_xda_l_reads - Buffer pool temporary XDA data logical reads
POOL_INDEX_L_READS	BIGINT	pool_index_l_reads - Buffer pool index logical reads
POOL_TEMP_INDEX_L_READS	BIGINT	pool_temp_index_l_reads - Buffer pool temporary index logical reads
POOL_DATA_P_READS	BIGINT	pool_data_p_reads - Buffer pool data physical reads
POOL_TEMP_DATA_P_READS	BIGINT	pool_temp_data_p_reads - Buffer pool temporary data physical reads
POOL_XDA_P_READS	BIGINT	pool_xda_p_reads - Buffer pool XDA data physical reads
POOL_TEMP_XDA_P_READS	BIGINT	pool_temp_xda_p_reads - Buffer pool temporary XDA data physical reads
POOL_INDEX_P_READS	BIGINT	pool_index_p_reads - Buffer pool index physical reads
POOL_TEMP_INDEX_P_READS	BIGINT	pool_temp_index_p_reads - Buffer pool temporary index physical reads
POOL_DATA_WRITES	BIGINT	pool_data_writes - Buffer pool data writes
POOL_XDA_WRITES	BIGINT	pool_xda_writes - Buffer pool XDA data writes
POOL_INDEX_WRITES	BIGINT	pool_index_writes - Buffer pool index writes
DIRECT_READ_TIME	BIGINT	direct_read_time - Direct read time
DIRECT_WRITE_TIME	BIGINT	direct_write_time - Direct write time
POOL_READ_TIME	BIGINT	pool_read_time - Total buffer pool physical read time
POOL_WRITE_TIME	BIGINT	pool_write_time - Total buffer pool physical write time
POOL_ASYNC_DATA_READS	BIGINT	pool_async_data_reads - Buffer pool asynchronous data reads
POOL_ASYNC_DATA_READ_REQS	BIGINT	pool_async_data_read_reqs - Buffer pool asynchronous read requests
POOL_ASYNC_DATA_WRITES	BIGINT	pool_async_data_writes - Buffer pool asynchronous data writes
POOL_ASYNC_INDEX_READS	BIGINT	pool_async_index_reads - Buffer pool asynchronous index reads
POOL_ASYNC_INDEX_READ_REQS	BIGINT	pool_async_index_read_reqs - Buffer pool asynchronous index read requests
POOL_ASYNC_INDEX_WRITES	BIGINT	pool_async_index_writes - Buffer pool asynchronous index writes
POOL_ASYNC_XDA_READS	BIGINT	pool_async_xda_reads - Buffer pool asynchronous XDA data reads
POOL_ASYNC_XDA_READ_REQS	BIGINT	pool_async_xda_read_reqs - Buffer pool asynchronous XDA read requests
POOL_ASYNC_XDA_WRITES	BIGINT	pool_async_xda_writes - Buffer pool asynchronous XDA data writes
POOL_NO_VICTIM_BUFFER	BIGINT	pool_no_victim_buffer - Buffer pool no victim buffers
POOL_LSN_GAP_CLNS	BIGINT	pool_lsn_gap_clns - Buffer pool log space cleaners triggered
POOL_DRTY_PG_STEAL_CLNS	BIGINT	pool_drty_pg_steal_clns - Buffer pool victim page cleaners triggered
POOL_DRTY_PG_THRSH_CLNS	BIGINT	pool_drty_pg_thrsh_clns - Buffer pool threshold cleaners triggered
VECTORED_IOS	BIGINT	vectored_ios - Number of vectored IO requests
PAGES_FROM_VECTORED_IOS	BIGINT	pages_from_vectored_ios - Total number of pages read by vectored IO
BLOCK_IOS	BIGINT	block_ios - Number of block IO requests
PAGES_FROM_BLOCK_IOS	BIGINT	pages_from_block_ios - Total number of pages read by block IO
UNREAD_PREFETCH_PAGES	BIGINT	unread_prefetch_pages - Unread prefetch pages
FILES_CLOSED	BIGINT	files_closed - Database files closed
POOL_DATA_GBP_L_READS	BIGINT	Reserved for future use
POOL_DATA_GBP_P_READS	BIGINT	Reserved for future use
POOL_DATA_LBP_PAGES_FOUND	BIGINT	Reserved for future use
POOL_DATA_GBP_INVALID_PAGES	BIGINT	Reserved for future use
POOL_INDEX_GBP_L_READS	BIGINT	Reserved for future use
POOL_INDEX_GBP_P_READS	BIGINT	Reserved for future use
POOL_INDEX_LBP_PAGES_FOUND	BIGINT	Reserved for future use
POOL_INDEX_GBP_INVALID_PAGES	BIGINT	Reserved for future use
POOL_ASYNC_DATA_GBP_L_READS	BIGINT	Reserved for future use
POOL_ASYNC_DATA_GBP_P_READS	BIGINT	Reserved for future use
POOL_ASYNC_DATA_LBP_PAGES_FOUND	BIGINT	Reserved for future use
POOL_ASYNC_DATA_GBP_INVALID_PAGES	BIGINT	Reserved for future use
POOL_ASYNC_INDEX_GBP_L_READS	BIGINT	Reserved for future use
POOL_ASYNC_INDEX_GBP_P_READS	BIGINT	Reserved for future use
POOL_ASYNC_INDEX_LBP_PAGES_FOUND	BIGINT	Reserved for future use
POOL_ASYNC_INDEX_GBP_INVALID_PAGES	BIGINT	Reserved for future use
POOL_XDA_GBP_L_READS	BIGINT	Reserved for future use
POOL_XDA_GBP_P_READS	BIGINT	Reserved for future use
POOL_XDA_LBP_PAGES_FOUND	BIGINT	Reserved for future use
POOL_XDA_GBP_INVALID_PAGES	BIGINT	Reserved for future use
POOL_ASYNC_XDA_GBP_L_READS	BIGINT	Reserved for future use
POOL_ASYNC_XDA_GBP_P_READS	BIGINT	Reserved for future use
POOL_ASYNC_XDA_LBP_PAGES_FOUND	BIGINT	Reserved for future use
POOL_ASYNC_XDA_GBP_INVALID_PAGES	BIGINT	Reserved for future use
POOL_ASYNC_READ_TIME	BIGINT	pool_async_read_time - Buffer Pool Asynchronous Read Time monitor element
POOL_ASYNC_WRITE_TIME	BIGINT	pool_async_write_time - Buffer pool asynchronous write time monitor element
BP_CUR_BUFFSZ	BIGINT	bp_cur_buffsz - Current Size of Buffer Pool monitor element
ADDITIONAL_DETAILS	BLOB(100K)	Reserved for future use