To provide concurrency control and prevent uncontrolled
data access, locks can be placed on resources like tables, data partitions,
table blocks, or table rows. A lock associates a resource with an
application to control how other applications access the same resource.
Though locks are required to manage data concurrency, locks can affect
performance.
The Locking Dashboard displays lock related performance information
for individual databases. The dashboard provides an overview section
that includes key time measures and event counters whose values might
be indicators of locking problems. You can use the lower sections
of the dashboard to investigate any areas of concern.
Note: The IBM® PureData System
for Operational Analytics is
not configured to collect locking metrics by default. To enable the
collection of locking metrics, click Edit Configuration on
the Databases page of the database performance monitor and
enable the locking profile in the configuration wizard.
- Investigating locking situations
- On the Currently Waiting Connections tab or Currently Blocking
Connections tab, select the waiting or blocking application that you
want to investigate and click Analyze. The
Analyze Locking Situation window opens and provides information about
all applications that are related to the specific locking situation.
Information is provided for the application that you selected and
any applications that are being blocked by that application (directly
or indirectly through other blocked applications). Information is
also provided for applications that might be blocking your selected
application (directly or indirectly). The dependency of these applications
to each other is displayed as a tree. Your selected application is
highlighted.
- Investigating deadlocks
- On the Locking Event tab, select an application with a deadlock
alert and click Analyze. The Deadlock in Application
window opens and provides information about the deadlock, participating
applications, locks, and executed SQL statements. Participant information
is displayed on a single tab so that you can compare the application
information. You can also view the statement history that led to the
deadlock and examine the current statement and recently run statements.
- Investigating lock waits and lock time outs
- On the Locking Event tab, select an
application with a lock wait or lock timeout alert and click Analyze.
The analysis window opens and provides information about the locks,
executed SQL statements, and participating applications.
If your lock investigation suggests problems with applications
or running statements, you can force applications or stop currently
running statements from the Locking Dashboard.