Specifies the transaction isolation level for transactions.
Syntax:
type TTransIsolation = (tiDirtyRead,
tiReadCommitted,
tiRepeatableRead,
tiSerializable );
property TransIsolation: TTransIsolation;
Description:
Use TransIsolation to specify the transaction isolation level for database transactions. Transaction isolation level determines how a transaction interacts with other simultaneous transactions when they work with the same tables, and how much a transaction sees of the work performed by other transactions.
TransIsolation can be any one of the values summarized in the following list:
tiDirtyRead:
Not implemented for PostgreSQL.
tiReadCommitted:
A statement can only see rows committed before it began. This is the default.
tiRepeatableRead:
All statements of the current transaction can only see rows committed before the first query or data-modification statement was executed in this transaction.
tiSerializable:
All statements of the current transaction can only see rows committed before the first query or data-modification statement was executed in this transaction. If a pattern of reads and writes among concurrent serializable transactions would create a situation which could not have occurred for any serial (one-at-a-time) execution of those transactions, one of them will be rolled back with a serialization_failure error.
Applications that use passthrough SQL for handling transactions must pass a transaction isolation level directly to the database server using the appropriate SQL statement.