I am thinking of using Citus opensource for dualnode cluster - my questions are basically 2: - if this kind of clustering is available - in the case of a failover is the slave node promoted to master? If yes - how - does it use WAL? - If such a way of clusterisation is not possible what is an alternative for that except pgpool?
Thank you.
Citus isn't a high-availability solution for single-node PostgreSQL. Citus shards/partitions your data across multiple servers, and can thus use multiple CPU cores in parallel for your queries or transactions. Citus is suitable for a variety of use-cases, and you can find more information on those here.
For high-availability, Citus can replicate data across multiple nodes, or you can set up streaming replication for each worker node. Citus Cloud uses streaming replication for each node, and you can find more information on how Citus Cloud manages HA on our documentation.