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You can use the
commit database option to specify one of these types of commit protocols for transaction engines:
The default is
For each protocol, durability is a database transaction property that ensures that changes made during a transaction are persistent and can be re-created if a storage manager terminates and restarts. The following table describes each
commit option argument. See also Choosing a Commit Protocol.
||TE sends a pre-commit message to each SM serving a modified storage group of the committing transaction. The TE then receives a pre-commit acknowledgment from each SM, and then sends a commit confirmation message to the client. See About the Safe Commit Protocol.|
||TE sends a commit message to SM or SSM and does not wait for confirmation that the transaction was durably recorded.|
For each modified storage group, specifies the number of SMs or SSMs that must confirm that the transaction was durably recorded before the TE reports the transaction as committed. The TE waits for the specified number of confirmations before sending a commit confirmation to the client.
A modified storage group is a storage group in which the transaction has inserted, deleted, or updated data serviced by that storage group.
If the optional
For each modified storage group, this option specifies the number of regions that must confirm that the transaction was durably recorded before the TE reports the transaction as committed.
In this release, the
If the optional
Consider the scenario in which there is one local region and two remote regions and
It is possible for the local region to include SMs/SSMs that service some but not all of the modified storage groups. This means that SMs/SSMs in the local region can confirm that the transaction was durably recorded for only a subset of the modified storage groups. In this case:
Note: The actual database process default for this option is
local. However, this is overwritten in all standard NuoDB templates to be
remote:1. You would see the default
local behavior only if you start a database process using the NuoDB Manager
start process te command.