RE: [Proposal] Add foreign-server health checks infrastructure

Dear Katsuragi-san,

Thank you for reviewing! PSA new patch set.

> ## v24-0001-Add-PQConncheck-and-PQCanConncheck-to-libpq.patch
> +    <varlistentry id="libpq-PQCanConncheck">
> +
> <term><function>PQCanConncheck</function><indexterm><primary>PQCan
> Conncheck</primary></indexterm></term>
> +     <listitem>
> +      <para>
> +       Returns the status of the socket.
> 
> Is this description right? I think this description is for
> PQConncheck. Something like "Checks whether PQConncheck is
> available on this platform." seems better.

It might be copy-and-paste error. Thanks for reporting.
According to other parts, the sentence should be started like "Returns ...".
So I followed the style and did cosmetic change.

> +/* Check whether the postgres server is still alive or not */
> +extern int PQConncheck(PGconn *conn);
> +extern int PQCanConncheck(void);
> 
> Should the names of these functions be in the form of PQconnCheck?
> Not PQConncheck (c.f. The section of fe-misc.c in libpq-fe.h).

Agreed, fixed.

> ## v24-0002-postgres_fdw-add-postgres_fdw_verify_connection_.patch
> +PG_FUNCTION_INFO_V1(postgres_fdw_verify_connection_states);
> +PG_FUNCTION_INFO_V1(postgres_fdw_verify_connection_states_all);
> +PG_FUNCTION_INFO_V1(postgres_fdw_can_verify_connection_states);
> 
> This patch adds new functions to postgres_fdw for PostgreSQL 16.
> So, I think it is necessary to update the version of postgres_fdw (v1.1
> to v1.2).

I checked postgres_fdw commit log, and it seemed that the version was
updated when SQL functions are added. Fixed.

> +    <term><function>postgres_fdw_verify_connection_states_all() returns
> boolean</function></term>
> +    <listitem>
> +     <para>
> +      This function checks the status of remote connections that are
> established
> +      by <filename>postgres_fdw</filename> from the local session to
> the foreign
> +      servers. This check is performed by polling the socket and allows
> 
> It seems better to add a description that states this function
> checks all the connections. Like the description of
> postgres_fdw_disconnect_all(). For example, "This function
> checks the status of 'all the' remote connections..."?

I checked the docs and fixed. Moreover, some inconsistent statements were
also fixed.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED