Usage Notes - Teradata Database

SQL Data Manipulation Language

Product
Teradata Database
Release Number
15.10
Language
English (United States)
Last Update
2018-10-06
dita:id
B035-1146
lifecycle
previous
Product Category
Teradata® Database

Locks and Concurrency

A DELETE statement sets a WRITE lock for the table, partitions, or row. For a nonconcurrent load isolated delete operation on a load isolated table, the delete operation sets an EXCLUSIVE lock.

For a SELECT subquery, the lock depends on the isolation level for the session, the setting of the AccessLockForUncomRead DBS Control field, and whether the subquery is embedded within a SELECT or DELETE statement.

 

Transaction Isolation Level

DBS Control AccessLockForUncomRead Field Setting

Default Locking Severity for Outer SELECT and Ordinary SELECT Subquery Operations

Default Locking Severity for SELECT Operations Embedded Within an UPDATE Request

SERIALIZABLE

FALSE

READ

READ

TRUE

READ

READ UNCOMMITTED

 

FALSE

READ

TRUE

ACCESS