Transaction Mode and Isolation Level

SAP ASE provides certain options that support transactions that must be compliant with SQL standards.

Set these options at the beginning of every session that requires SQL-standards-compliant transactions.

• Choose a Transaction Mode
  SAP ASE supports chained and unchained transaction modes. You can set either mode using the chained option of the set command.
• Choose an Isolation Level
  The ANSI SQL standard defines four levels of isolation for transactions. Each isolation level specifies the kinds of actions that are not permitted while concurrent transactions are executing. Higher levels include the restrictions imposed by the lower levels.
• Compliance with SQL Standards
  To get transactions that comply with SQL standards, you must set the chained and transaction isolation level 3 options at the beginning of every application that changes the mode and isolation level for subsequent transactions.
• Use the Lock Table Command to Improve Performance
  The lock table command allows you to explicitly request a table lock for the duration of a transaction. This is useful when an immediate table lock may reduce the overhead of acquiring a large number of row or page locks and save locking time.