ASA SQL User's Guide
Using Transactions and Isolation Levels
Particular concurrency issues
Data definition statements that change an entire table, such as CREATE INDEX, ALTER TABLE, and TRUNCATE TABLE, are prevented whenever the statement table is currently being used by another connection. These data definition statements can be time consuming and the database server will not process requests referencing the same table while the command is being processed.
The CREATE TABLE statement does not cause any concurrency conflicts.
The GRANT statement, REVOKE statement, and SET OPTION statement also do not cause concurrency conflicts. These commands affect any new SQL statements sent to the database server, but do not affect existing outstanding statements.
GRANT and REVOKE for a user are not allowed if that user is connected to the database.
Data definition statements and replicated databasesUsing data definition statements in replicated databases requires special care. For more information see the separate manual entitled Data Replication with SQL Remote . |