Using Locks
Teradata MultiLoad uses two kinds of long-term locks on the tables involved in a Teradata MultiLoad task:
The locks placed on target tables by Teradata MultiLoad are write locks, or less, in most situations. The locking levels are imposed by the utility for:
The most restrictive exclusive lock is used only when a RELEASE MLOAD statement is executed after a Teradata MultiLoad task has been suspended or aborted.
Table 18 describes the of locks imposed on tables by Teradata MultiLoad tasks.
Lock Type |
Description |
Access |
An access lock allows selection of data from a table that may be locked for write access. Teradata MultiLoad maintains access locks against the target tables during the acquisition phase. Note: There is concurrent access lock select access to all affected target tables in both import and delete tasks. |
Exclusive |
Teradata MultiLoad uses an exclusive lock to support the manual recovery procedure when a RELEASE MLOAD statement is executed after a Teradata MultiLoad task has been suspended or aborted. The RELEASE MLOAD function: |
Teradata MultiLoad Acquisition |
A Teradata MultiLoad acquisition lock is a flag in the table header that effectively rejects certain types of Teradata SQL access statements. An acquisition lock: Teradata MultiLoad maintains acquisition locks against each: |
Teradata MultiLoad Application |
A Teradata MultiLoad application lock is a flag in the table header that effectively rejects certain types of Teradata SQL access statements. An application lock: Teradata MultiLoad maintains application locks against each: |
Write |
A write lock enables a single user to modify the table. Teradata MultiLoad maintains write locks against each: Note: Use access lock select access when querying the Teradata MultiLoad error tables to prevent lock time-outs that could cause Teradata MultiLoad task aborts. |