PostgreSQL streaming replication for high load

Question

I am planning to migrate my production oracle cluster to postgresql cluster. Current systems support 2000TPS and in order to support that TPS, I would be very thankful if someone could clarify bellow.

1) What is the best replication strategy ( Streaming or DRBD based replication)

2) In streaming replication, can master process traffic without slave and when slave come up does it get what lost in down time ?

Answer 1

About TPS - it depends mainly on your HW and PostgreSQL configuration. I already wrote about it on Stackoverflow in this answer . You cannot expect magic on some notebook-like configuration. Here is my text " PostgreSQL and high data load application ".

1) Streaming replication is the simplest and almost "painless" solution. So if you want to start quickly I highly recommend it.

2) Yes but you have to archive WAL logs. See below.

All this being said here are links I would recommend you to read:

• how to set streaming replication
• example of WAL log archiving script

But of course streaming replication has some caveats which you should know:

• problem with increasing some parameters like max_connections
• how to add new disk and new tablespace to master and replicas

Answer 2

1. There is no “best solution” in this case. Which solution you pick depends on your requirements.
   • Do you need a guarantee of no data lost?
   • How big a performance hit can you tolerate?
   • Do you need failover or just a backup?
   • Do you need PITR (Point In Time Recovery)?
2. By default, I think a failed slave will be ignored. Depending on your configuration, the slave might take a long time to recover after eg a boot.

I'd recommend you read https://www.postgresql.org/docs/10/static/different-replication-solutions.html