From: Drouvot, Bertrand <bertranddrouvot.pg@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Add two missing tests in 035_standby_logical_decoding.pl
Date: Mon, 24 Apr 2023 14:06:59 +0200
Message-ID: <74f80bc1-6b39-b2a8-c716-98beefb75e0b@gmail.com> (raw)
In-Reply-To: <CAA4eK1JeAZ9MUf3qPAOA5t9=e_vPJSEi6nZ3OygDYi-913eO+Q@mail.gmail.com>
References: <2fefa454-5a70-2174-ddbf-4a0e41537139@gmail.com>
<CALDaNm2raNJrEF_ucDeTV_AygYutVb1bz2SrKO06YdVVG1gf2A@mail.gmail.com>
<9ab1827c-9a57-8c48-59b2-c5fb62c21be3@gmail.com>
<CAA4eK1KVoAjzT49BwKCih0A+1PE7hm=4PwQ-_VUr9YteFJRB5g@mail.gmail.com>
<CAA4eK1JeAZ9MUf3qPAOA5t9=e_vPJSEi6nZ3OygDYi-913eO+Q@mail.gmail.com>
Hi,
On 4/24/23 11:45 AM, Amit Kapila wrote:
> On Mon, Apr 24, 2023 at 11:54 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>>
>> On Mon, Apr 24, 2023 at 11:24 AM Drouvot, Bertrand
>> <bertranddrouvot.pg@gmail.com> wrote:
>>>
>>
>> Few comments:
>> ============
>>
>
> +# We can not test if the WAL file still exists immediately.
> +# We need to let some time to the standby to actually "remove" it.
> +my $i = 0;
> +while (1)
> +{
> + last if !-f $standby_walfile;
> + if ($i++ == 10 * $default_timeout)
> + {
> + die
> + "could not determine if WAL file has been retained or not, can't continue";
> + }
> + usleep(100_000);
> +}
>
> Is this adhoc wait required because we can't guarantee that the
> checkpoint is complete on standby even after using wait_for_catchup?
Yes, the restart point on the standby is not necessary completed even after wait_for_catchup is done.
> Is there a guarantee that it can never fail on some slower machines?
>
We are waiting here at a maximum for 10 * $default_timeout (means 3 minutes) before
we time out. Would you prefer to wait more than 3 minutes at a maximum?
> BTW, for the second test is it necessary that we first ensure that the
> WAL file has not been retained on the primary?
>
I was not sure it's worth it too. Idea was more: it's useless to verify it is removed on
the standby if we are not 100% sure it has been removed on the primary first. But yeah, we can get
rid of this test if you prefer.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
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Cc: bertranddrouvot.pg@gmail.com, amit.kapila16@gmail.com, vignesh21@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: Add two missing tests in 035_standby_logical_decoding.pl
In-Reply-To: <74f80bc1-6b39-b2a8-c716-98beefb75e0b@gmail.com>
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