Latch Counters

This topic shows detailed information about "Statistics - Latch Counters".

The QVLS latch counters represent the number of suspends that were performed by agents that attempted to obtain a latch.

There is not a one-to-one relationship between the QVLS counters and IFCID 56 or 57, because an agent might suspend multiple times or not at all, while trying to obtain a latch. That is why the QVLS counters are not directly related to Accounting Class 3.

Statistics - Latch Counters

The field labels shown in the following sample layout of "Statistics - Latch Counters" are described in the following section.

LATCH CNT   /SECOND   /SECOND   /SECOND   /SECOND
---------  --------  --------  --------  --------
LC01-LC04      0.00      0.00      0.00      0.00
LC05-LC08      0.00      0.00      0.00      0.00
LC09-LC12      0.00      0.00      0.00      0.00
LC13-LC16      0.00      0.00      0.00      0.00
LC17-LC20      0.00      0.00      0.00      0.00
LC21-LC24      0.00      0.00      0.00      0.01
LC25-LC28      0.00      0.00      0.00      0.00
LC29-LC32      0.00      0.01      0.00      0.00
LC254          0.00

LC01

This field is infrequently used.

Field Name: QVLSLC01

LC02

The predominant latch usage is: Global authorization cache.

Field Name: QVLSLC02

LC03

The predominant latch usage is: DDF disconnect.

Field Name: QVLSLC03

LC04

Start of change The predominant latch usage is: SYSSTRING cache. End of change

Field Name: QVLSLC04

LC05

The predominant latch usage is: IRLM data sharing exits or RLF.

Field Name: QVLSLC05

LC06

The predominant latch usage is: Data sharing index split.

Field Name: QVLSLC06

LC07

The predominant latch usage is: Index lotch and OBD allocation.

Field Name: QVLSLC07

LC08

The predominant latch usage is: Query parallelism.

Field Name: QVLSLC08

LC09

The predominant latch usage is: Utilities or stored procedure URIDs.

Field Name: QVLSLC09

LC10

Start of change The predominant latch usage is for Sequence objects (stand-alone and table-based Identity Column). DB2 12 latch contention can be significantly reduced for the Identity Column in a data-sharing environment because of the reduction in log force write. End of change

Field Name: QVLSLC10

LC11

Start of change The predominant latch usage is for Sequence objects (stand-alone and table-based Identity Column) for concurrent transactions. DB2 12 latch contention can be significantly reduced for the Identity Column in a data-sharing environment because of the reduction in log force write. End of change

Field Name: QVLSLC11

LC12

Start of change The predominant latch usage is database allocation control latch (latch class X'0C') or WebSphere® global transaction ID latch (latch class X'4C'). End of change

Field Name: QVLSLC12

LC13

The predominant latch usage is: Pageset operations.

Field Name: QVLSLC13

LC14

Start of change The predominant latch usage is represented by various buffer pool related activities, including buffer pool control block and pool serialization. End of change

Field Name: QVLSLC14

LC15

The predominant latch usage is: ARCHIVE LOG MODE(QUIESCE).

Field Name: QVLSLC15

LC16

Start of change The predominant latch usage is: UR synonym chain. End of change

Field Name: QVLSLC16

LC17

The predominant latch usage is: RURE chain.

Field Name: QVLSLC17

LC18

The predominant latch usage is: DDF resynch list.

Field Name: QVLSLC18

LC19

Start of change The predominant latch usage is logical log write (in contrast to physical log write). End of change

Field Name: QVLSLC19

LC20

The predominant latch usage is: System checkpoint.

Field Name: QVLSLC20

LC21

The predominant latch usage is: Accounting rollup.

Field Name: QVLSLC21

LC22

The predominant latch usage is: Internal checkpoint.

Field Name: QVLSLC22

LC23

Start of change The predominant latch usage is Buffer Manager latch for page latch contention timer queue or deferred write latch. Both types of latches have latch class X'17'. End of change

Field Name: QVLSLC23

LC24

Start of change The predominant latch usage is EDM LRU latch or Buffer Manager prefetch scheduling latch. EDM LRU latch can be identified by latch class X'18' while Buffer Manager prefetch scheduling latch can be identified by latch class X'38' in a latch contention trace. End of change

Field Name: QVLSLC24

LC25

Start of change The predominant latch usage is: EDM hash latch. End of change

Field Name: QVLSLC25

LC26

The predominant latch usage is: Dynamic statement cache.

Field Name: QVLSLC26

LC27

Start of change The predominant latch usage is: stored procedure queue latch and UDF. End of change

Field Name: QVLSLC27

LC28

The predominant latch usage is: Stored procedures or authorization cache.

Field Name: QVLSLC28

LC29

The predominant latch usage is: Field procs and DDF transaction manager.

Field Name: QVLSLC29

LC30

The predominant latch usage is: Agent services.

Field Name: QVLSLC30

LC31

The predominant latch usage is: Storage manager.

Field Name: QVLSLC31

LC32

Start of change The predominant latch usage is shared storage pool latch. End of change

Field Name: QVLSLC32

LC254

The predominant latch usage is: Index latch.

Field Name: QVLSLC254

Feedback