PostgreSQL version:

tcp_keepalives_count

Specifies the number of TCP keepalives that can be lost before the server's connection to the client is considered dead. A value of 0 uses the system default. This parameter is supported only on systems that support TCP_KEEPCNT or an equivalent socket option; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero.

This parameter is not supported on Windows, and must be 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.

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