| From: | "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
|---|---|
| To: | "MikalaiKeida(at)ibagroup(dot)eu" <MikalaiKeida(at)ibagroup(dot)eu> |
| Cc: | "AYahorau(at)ibagroup(dot)eu" <AYahorau(at)ibagroup(dot)eu>, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, "Jamison, Kirk" <k(dot)jamison(at)jp(dot)fujitsu(dot)com>, "Michael Paquier" <michael(at)paquier(dot)xyz>, "Nagaura, Ryohei" <nagaura(dot)ryohei(at)jp(dot)fujitsu(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com> |
| Subject: | RE: Timeout parameters |
| Date: | 2019-03-15 08:04:20 |
| Message-ID: | 0A3221C70F24FB45833433255569204D1FBC7FD1@G01JPEXMBYT05 |
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| Lists: | pgsql-hackers |
From: MikalaiKeida(at)ibagroup(dot)eu [mailto:MikalaiKeida(at)ibagroup(dot)eu]
> In case of failure PQcancel() terminates in 'socket_timeout'. So, control
> to the end-user in such a failure situation will be returned in 2 *
> 'socket_timeout' interval. It is much better than hanging forever in some
> specific cases. Moreover, such solution will not lead to the overloading
> of PostgreSQL server by abnormally ignored 'heavy' queries results by
> end-users.
Oops, unfortunately, PQcancel() does not follow any timeout parameters... It uses a blocking socket.
Also, I still don't think it's a good idea to request cancellation. socket_timeout should be sufficiently longer than the usually expected query execution duration. And long-running queries should be handled by statement_timeout which indicates the maximum tolerable query execution duration.
For example, if the usually expected query execution time is 100 ms, statement_timeout can be set to 3 seconds and socket_timeout to 5 seconds.
Regards
Takayuki Tsunakawa
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