DSDT: Durable Scripts containing Database Transactions

Abstract

DSDT is a proposed method for creating durable scripts which contain short ACID transactions as components. Workflow scripts are an example. The context of the script is made durable by writing a log record whenever an event occurs which cannot be replayed. Log checkpoints are used to minimize the recovery time. DSDT can be written in stand-alone mode, communicating with a DBMS by transactional remote procedure calls and maintaining its own logging system, or it can be made part of a DBMS by modifying the DBMS transaction manager source code. DSDT provides a panic button (signal-exit) and the ability to specify what action should be taken on restart after a system failure. The programmer can also specify actions, such as "compensation" transactions, to be taken after another signal (signal-cancel) arrives. DSDT enables most extended transaction models to be expressed in scripts modulo the guarantees of compensation. Recovery after system failure is shown to be correct.