Abstract: Techniques are described for preserving the inflight sessions failing over from a primary database to the replicated logical database of the primary database. In an implementation, prior to failover, when the primary database server receives a commit for a transaction, the process stores a commit indication that the transaction has been committed by performing a corresponding SQL command. The commit indication is replicated to the logical replica database by virtue of the replication of the SQL command and its execution on the logical replica database. Accordingly, the standby database server in the failover session may successfully request for the outcome of the transaction. Techniques are also described for the client-side LOB references to be preserved when failing over to the logical replica database, for AS OF queries preserved, and for versioning of checksums, signatures and structures across logical replicas.

Abstract: A computer readable medium storing a database query language statement tuning base in a tuning base memory location is disclosed. The tuning base includes tuning information for one or more query language statements. The tuning information for each statement includes one or more tuning actions for the statement, and a signature to allow an optimizer to identify the one or more tuning actions for the statement.

Abstract: A method of logical database snapshot for log-based replication in described that need not incur a quiescence of an operational database. Baselines for the overall snapshot operation and for each table replication are recorded in such a way that subsequent log-based replication can distinguish which redo records to apply and which to discard. The baselines may be recorded as system change numbers negotiated according to a distributed protocol for synchronizing a sequence number, and records from the redo log are applied on the logical standby system based on the recorded system change numbers.