Re: Libpq support to connect to standby server as priority - Mailing list pgsql-hackers

From Haribabu Kommi
Subject Re: Libpq support to connect to standby server as priority
Date
Msg-id CAJrrPGd4YeA+N=xC+1XPVoGzMCATJZY4irVQEJ6i0aPqorUi7g@mail.gmail.com
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In response to Re: Libpq support to connect to standby server as priority  (Haribabu Kommi <kommi.haribabu@gmail.com>)
Responses Re: Libpq support to connect to standby server as priority
List pgsql-hackers

On Fri, Mar 22, 2019 at 7:32 AM Haribabu Kommi <kommi.haribabu@gmail.com> wrote:

On Fri, Mar 22, 2019 at 6:57 AM Robert Haas <robertmhaas@gmail.com> wrote:
On Thu, Mar 21, 2019 at 2:26 AM Haribabu Kommi <kommi.haribabu@gmail.com> wrote:
> Based on the above new options that can be added to target_session_attrs,
>
> primary - it is just an alias to the read-write option.
> standby, prefer-standby - These options should check whether server is running in recovery mode or not
> instead of checking whether server accepts read-only connections or not?

I think it will be best to have one set of attributes that check
default_transaction_read_only and a differently-named set that check
pg_is_in_recovery().  For each, there should be one value that looks
for a 'true' return and one value that looks for a 'false' return and
perhaps values that accept either but prefer one or the other.

IOW, there's no reason to make primary an alias for read-write.  If
you want read-write, you can just say read-write.  But we can make
'primary' or 'master' look for a server that's not in recovery and
'standby' look for one that is.

OK, I agree with opinion. I will produce a patch for those new options.

Here I attached WIP patch for the new options along with other older patches.
The basic cases are working fine, doc and tests are missing.

Currently this patch doesn't implement the GUC_REPORT for recovery mode
yet. I am yet to optimize the complex if check.

Regards,
Haribabu Kommi
Fujitsu Australia
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