Hello,
We have been trying to figure out possible solutions to the following problem in streaming replication Consider following scenario:
If master receives commit command, it writes and flushes commit WAL records to the disk, It also writes and flushes data page related to this transaction.
The master then sends WAL records to standby up to the commit WAL record. But before sending these records if failover happens then, old master is ahead of standby which is now the new master in terms of DB data leading to inconsistent data .
One solution to avoid this situation is have the master send WAL records to standby and wait for ACK from standby committing WAL files to disk and only after that commit data page related to this transaction on master.
The main drawback would be increased wait time for the client due to extra round trip to standby before master sends ACK to client. Are there any other issues with this approach?
Thank you,
Samrat
