backends.postgresql.server-selection

server-selection

Selects the server-selection algorithm used when multiple PostgreSQL server blocks are configured. See Backend Load Balancing for algorithm details, tie-breaking rules, pool-skip behavior, and full examples.

Allowed values

• fallback - Tries servers in priority order (default).
• round-robin - Distributes requests across available servers in rotation.
• hash-balance - Hashes one or more configured AAA context fields to select a stable preferred server.
• least-connections - Routes to the server with the fewest in-use connections.
• no-fallback - Tries only the highest-priority available server; failures are not retried on other servers.

Default: fallback

Example

postgres "POSTGRES_HA" {
    server-selection fallback;

    server "primary" {
        host "pg-primary.example.com";
        priority 0;
        # ...
    }

    server "replica" {
        host "pg-replica.example.com";
        priority 1;
        # ...
    }

    query "FIND_USER" { ... }
}