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Overview of transactions and versioning
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Transactions are atomic. In other words, Adaptive Server IQ executes all the
statements within a transaction as a unit. At the end of each transaction,
changes can be committed to make them permanent. If for any reason all the
commands in the transaction do not process properly, then some or all of the
intermediate changes can be undone, or rolled back. The user application
controls the conditions under which changes are committed or rolled back. In
DBISQL the
AUTO_COMMIT option can be used to control commits and
rollbacks automatically.
Transactions break the work of each user into small blocks. The completion of
each block marks a point at which the information is self-consistent.
Transaction processing is fundamental to ensuring that a database contains
correct information.
Note Adaptive Server IQ processes transactions quite differently from the way
Adaptive Server Anywhere does when it operates without IQ. This chapter
describes how Adaptive Server IQ handles transactions. If you are working in
an Anywhere-only database, see the Adaptive Server Anywhere User’s Guide
for information on transactions and locking.
Using transactions
Adaptive Server IQ allows commands to be grouped into transactions. In most
cases, IQ transactions begin and end automatically, based on the commands
being issued, and the options set. You can also issue explicit commands to
begin or end a transaction.
Starting transactions
Transactions start automatically with one of the following events:
• The first statement following a connection to a database.
• The first statement following the end of a previous transaction.
Completing transactions
Transactions complete with one of the following events:
•A
COMMIT statement makes the changes to the database permanent.