Cluster Database Data Block Transfer with Delayed Log Flush

The patent applies preliminary action by transferring data blocks before all redo records are durably stored. The system performs the transfer operation in advance and then completes the durability requirement later, allowing the transfer to proceed without unnecessary delay while still ensuring data integrity through subsequent durability checks and conditional transfers.

The patent changes the parameter of transfer timing from strict sequential (wait for durability) to conditional (transfer when ready, with durability checked later). By introducing a conditional transfer mechanism where the source instance can transfer data blocks at any time and the destination instance performs durability checks, the system optimizes transfer efficiency while maintaining reliability through parameter modification rather than rigid constraint.

The patent implements feedback by having the destination instance receive and process durability information from the sourceinstance. The source instance provides feedback about which redo records are durably stored, and the destinationinstance uses this feedback to determine whether to apply changes conditionally. This feedback mechanism allows efficient transfers while managing data loss risk through informed conditional application of changes.

The patent applies beforehand cushioning by preparing the destinationinstance to handle potential data loss scenarios. The destinationinstance receives durability information in advance and is configured to conditionally apply changes only when durability is confirmed or to roll back if durability fails. This preparatory cushioning protects against data loss without requiring synchronous durability completion.