Re: Libpq support to connect to standby server as priority
| От | Haribabu Kommi |
|---|---|
| Тема | Re: Libpq support to connect to standby server as priority |
| Дата | |
| Msg-id | CAJrrPGcwt0LLLzDF9c3-zWrESJCJko-HovDOrMobkaWQaJ5YUw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Libpq support to connect to standby server as priority (Haribabu Kommi <kommi.haribabu@gmail.com>) |
| Ответы |
Re: Libpq support to connect to standby server as priority
|
| Список | pgsql-hackers |
On Fri, Sep 28, 2018 at 5:31 PM Haribabu Kommi <kommi.haribabu@gmail.com> wrote:
On Thu, Jul 19, 2018 at 10:59 PM Haribabu Kommi <kommi.haribabu@gmail.com> wrote:On Wed, Jul 18, 2018 at 10:53 PM Robert Haas <robertmhaas@gmail.com> wrote:On Wed, Jul 4, 2018 at 9:14 AM, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
> What about keeping the first successful connection open and storing it in a
> variable if we are in "prefer-read" mode.
> If we get the read-only connection we desire, close that cached connection,
> otherwise use it.
I like this idea. If I recall correctly, the logic in this area is
getting pretty complex, so we might need to refactor it for better
readability and maintainability.OK. I will work on the code refactoring first and then provide theprefer-read option on top it.commits d1c6a14bacf and 5ca00774194 have refactored the logicof handling the different connection states.Attached is a rebased patch after further refactoring the new optioncode for easier maintenance.
[some how i didn't receive this mail, copy pasted from mailing list ]
>The code is much more readable now, thanks.
Thanks for the review.
>--- a/src/interfaces/libpq/libpq-int.h
>+++ b/src/interfaces/libpq/libpq-int.h
>@@ -397,6 +397,7 @@ struct pg_conn
> int nconnhost; /* # of hosts named in conn string */
> int whichhost; /* host we're currently trying/connected to */
> pg_conn_host *connhost; /* details about each named host */
>+ int read_write_host_index; /* index for first read-write host in connhost */
>
> /* Connection data */
> pgsocket sock; /* FD for socket, PGINVALID_SOCKET if
>
>
>I think the comment could use more love.
>
>This would be the place to document the logic:
>Initial value is -1, then then index of the first working server
>we found, and -2 for the second attempt to connect to that server.
Added comments along the lines that you mentioned. And also try
to update some more comments.
>I notice that you don't keep the first connection open, but close
>and reopen it. I guess that is a matter of taste, but it would be
>easier on resources (and reduce connection time) if the connection
>were kept open.
>Admittedly, it would be more difficult and might further complicate
>code that is not very clear as it is.
Yes, I didn't add that logic of keeping the first connection open, Currently
I feel that adds more complexity in supporting the same. If everyone feels
that is required, I will add that logic.
Updated patch attached.
Regards,
Haribabu Kommi
Fujitsu Australia
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