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 CAJrrPGeRhaQG=2q15hrOcqb90A0NwE-G33XdHS2KgfmeNBiFEg@mail.gmail.com
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In response to RE: Libpq support to connect to standby server as priority  ("Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>)
Responses RE: Libpq support to connect to standby server as priority  ("Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>)
List pgsql-hackers

On Fri, Jan 18, 2019 at 5:33 PM Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com> wrote:
From: Tsunakawa, Takayuki [mailto:tsunakawa.takay@jp.fujitsu.com]
> As for prefer-standby/prefer-read, if host parameter specifies host1,host2
> in this order, and host1 is the primary with
> default_transaction_read_only=true, does the app get a connection to host1?
> I want to connect to host2 (standby) only if host1 is down.

Oops, reverse -- I wanted to say "I want to connect to host1 (primary) only if host2 is down."

Thanks for finding out the problem, how about the following way of checking
for prefer-read/prefer-standby.

1. (default_transaction_read_only = true and recovery = true)
2. If none of the host satisfies the above scenario, then recovery = true
3. Last check is for default_transaction_read_only = true

Regards,
Haribabu Kommi
Fujitsu Australia

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