Dear Horiguchi-san, Fujii-san,
> > I understood here as removing following mechanism from core:
> >
> > * disable timeout at end of tx.
> > * skip if held off or read commands
>
> I think we're on the same page. Anyway query cancel interrupt is
> ignored while rading input.
>
> > > - If an existing connection is found to be dead, just try canceling
> > > the query (or sending query cancel).
> > > One issue with it is how to show the decent message for the query
> > > cancel, but maybe we can have a global variable that suggests the
> > > reason for the cancel.
> >
> > Currently I have no good idea for that but I'll try.
>
> However, I would like to hear others' opnions about the direction, of
> course.
>
Based on the idea, I re-implemented the feature. Almost all feature is
moved to postgres_fdw. The abstract of my patch is as follows:
# core
* Exposes QueryCancelMessage for error reporting
* Uses above if it was not NULL
# postgres_fdw
* Defines new GUC postgres_fdw.health_check_interval.
It is renamed simpler.
* Registers a timeout when initializing connection hash.
* Raises SIGINT and sets QueryCancelMessage to message.
if detects a connection lost.
I also attached a test as zipped file for keep cfbot quiet.
When connection lost is detected, the following message will show:
```
ERROR: Foreign Server (servername) might be down.
```
How do you think?
Best Regards,
Hayato Kuroda
FUJITSU LIMITED
