Investigating Query Blocks and Delays - Teradata Database

Investigating Query Blocks and Delays

Most blocks are momentary and do not require attention. However, if a block persists, you can investigate it to identify the cause and determine whether further action is required.

1 Use the Teradata Viewpoint Query Monitor portlet to monitor the parameters related to query blocks and delays.

State	Description
Blocked	Indicates that a session query is held up by a lock on an object that the query is attempting to access.
Blocked Time	How long the query has been blocked. Momentary locks are a normal part of database operation. Persistent locks may indicate: A runaway query or hung query that cannot complete and release its locks, and which should be aborted A long-executing query, such as large-scale update or backup operation, which should be rescheduled to avoid resource contention
Delayed	Indicates that the query is in a delay queue caused by a workload rule.

2 Click the session ID for the query to access the Details View.

If a query is blocked, see the Blocked By tab for details

If the query is delayed, the Delay tab provides details about the cause of the delay

3 You can also use the Lock Viewer portlet to find out additional details about the block:

Block Time

Database

Table

Delay

Blocked User

Blocking Level

Blocking User

Additional Tools for Analyzing Lock Problems

The following table provides suggestions for analyzing and solving lock problems.

Tool	Analysis	Solution
Lock Display	Transaction locks	Determine which session is holding the lock that blocks others.
Query Session	Blocked session	Abort the session causing blocked transactions.
Show Locks	Host utility (HUT) locks; that is, locks placed by a client-based utility, such as Archive and Recovery	Submit RELEASE LOCKS as either an Archive and Recovery command or an SQL statement.