| Type: | integer |
| Default: | 0 |
| Min: | 0 |
| Max: | 2147483647 |
| Context: | user |
| Restart: | false |
Specifies the number of TCP keepalive messages that can be lost before the server's connection to the client is considered dead. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_KEEPCNT or an equivalent socket option (which does not include Windows); on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero.
Recommendations
The three tcp_keepalive settings help manage a system which tends to have "undead" connection/query processes. For systems which support them, you can regulate checking that connections are still "live" end-to-end to kill them off. Not needed if you're not having a problem. Should be synchronized with the new TCP keepalive support in libpq on the client side.