11.4.38. TimeDelay (delay) Filter
The TimeDelayFilter delays writing events to the THL and should be used
only on slaves in the
stage. This delays writing the transactions into the THL files, but allows
the application of the slave data to the database to continue without
TimeDelay delays the application of
transactions recorded in the THL. The delay can be used to allow
point-in-time recovery of DML operations before the transaction has been
applied to the slave, or where data may need to be audited or checked
before transactions are committed.
For effective operation, master and slaves should be synchronized using
NTP or a similar protocol.
To enable the
tpm command to enable the filter operation and the
required delay. For example, to enable the delay for 900 seconds:
./tools/tpm update alpha --hosts=host1,host2,host3 \
Time delay of transaction events should be performed with care, since the
delay will prevent a slave from being up to date compared to the master.
In the event of a node failure, an up to date slave is required to ensure
that data is safe.