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SET TRANSACTION


Sets transaction modes for transactions.

Usage

Embedded/Interactive/Procedural.

Description

The following table summarizes, for each of the four isolation levels, which of the affects described above are guaranteed never to occur, or must be accepted as possible, where there are concurrent transactions:

Isolation Level
1. Dirty Read
2. Non-repeatable Read
3. Phantoms
READ UNCOMMITTED
POSSIBLE
POSSIBLE
POSSIBLE
READ COMMITTED
NEVER OCCURS
POSSIBLE
POSSIBLE
REPEATABLE READ
NEVER OCCURS
NEVER OCCURS
POSSIBLE
SERIALIZABLE
NEVER OCCURS
NEVER OCCURS
NEVER OCCURS

Restrictions

The SET TRANSACTION statement may not be issued within a transaction.

Notes

The SET TRANSACTION START statement is generally issued at the beginning of a session, to set the start mode for transactions. Changing the start mode for transactions in the middle of a session is not generally recommended.

The SET SESSION statement can be used to define the default settings for the SET TRANSACTION READ, SET TRANSACTION ISOLATION LEVEL and SET TRANSACTION DIAGNOSTICS SIZE options.

Standard Compliance

Standard
Compliance
Comments
X/Open-95
SQL92
EXTENDED
Support for SET TRANSACTION START is a Mimer SQL extension.



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