Message-ID: <09613643-31e9-49f0-ada6-01ebdfa95fb7@gmail.com>
Date: Tue, 5 Dec 2023 14:38:12 +0100
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Synchronizing slots from primary to standby
Content-Language: en-US
To: shveta malik <shveta.malik@gmail.com>
Cc: Nisha Moond <nisha.moond412@gmail.com>,
 Amit Kapila <amit.kapila16@gmail.com>,
 "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>,
 Peter Smith <smithpb2250@gmail.com>,
 "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
 Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
 Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
 Bruce Momjian <bruce@momjian.us>, Ashutosh Sharma <ashu.coek88@gmail.com>,
 Andres Freund <andres@anarazel.de>,
 pgsql-hackers <pgsql-hackers@postgresql.org>,
 Ajin Cherian <itsajin@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>
References: <CAJpy0uC+2agRtF3H=n-hW5JkoPfaZkjPXJr==y3_PRE04dQvhw@mail.gmail.com>
 <65326908-f1ef-40ce-acc6-414801c30946@gmail.com>
 <CAJpy0uDKPK537ZW8CAjDVmSjHtBKCzTUzq=it84SrA0PfoWFCg@mail.gmail.com>
 <OS0PR01MB57161938A348977127D56A6694BDA@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <1789e94e-8266-44d1-95e4-7f41abc27d0d@gmail.com>
 <OS0PR01MB5716DCFD6CC89C2F243B55939483A@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <828dcda4-50c2-4069-bdc3-9e8c90c943d7@gmail.com>
 <CAA4eK1LxGd8GACR36KdtbVaQeKsV9B5-LuBf2o721x6OZ=_wWg@mail.gmail.com>
 <6694284d-c847-42df-8f76-6efa8eeeb0df@gmail.com>
 <CABdArM5zvpFcOF=_0W-E5bjqjrC2MK+EtFN0UfP43zvaFOc8QA@mail.gmail.com>
 <CAJpy0uCBHRX-GSKCeVza44kFEC=uTMD_6uzuXXnbUX32Vt-g8Q@mail.gmail.com>
 <2fdc471d-2eee-4c29-9f26-d7f5dcc8cd53@gmail.com>
 <CAJpy0uDiffV66DofhxZr97Sw2U_-ZkdNCjdRt9tKhnf-CxW57Q@mail.gmail.com>
 <40e1d73f-a09d-4608-8efa-750c998c3287@gmail.com>
 <CAJpy0uAt7c8ccND7yejoH=SmawCDON-DN2W=qhrKbNJ506ovYQ@mail.gmail.com>
From: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
In-Reply-To: <CAJpy0uAt7c8ccND7yejoH=SmawCDON-DN2W=qhrKbNJ506ovYQ@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Archived-At: <https://www.postgresql.org/message-id/09613643-31e9-49f0-ada6-01ebdfa95fb7%40gmail.com>
Precedence: bulk

Hi,

On 12/5/23 11:29 AM, shveta malik wrote:
> On Tue, Dec 5, 2023 at 2:18 PM Drouvot, Bertrand
> <bertranddrouvot.pg@gmail.com> wrote:
>> Wouldn't that make sense to move it once we are sure that
>> walrcv_startstreaming() returns true and first_stream is true, here?
>>
>> "
>>                           if (first_stream)
>> +                       {
>>                                   ereport(LOG,
>>                                                   (errmsg("started streaming WAL from primary at %X/%X on timeline %u",
>>                                                                   LSN_FORMAT_ARGS(startpoint), startpointTLI)));
>> +                               SpinLockAcquire(&walrcv->mutex);
>> +                               walrcv->walRcvState = WALRCV_STREAMING;
>> +                               SpinLockRelease(&walrcv->mutex);
>> +                       }
>> "
>>
> 
> Yes, it makes sense and is the basis for current slot-sync worker
> changes being discussed.

I think this change deserves its own dedicated thread and patch, does
that make sense?

If so, I'll submit one.

>>
>> 2) and 3) looks good to me but with a check on walrcv->walRcvState
>> looking for WALRCV_STREAMING state instead of looking for a non null
>> WalRcv->pid.
> 
> yes. But I think, the worker should enter no-op, when walRcvState is
> WALRCV_STOPPED and not when walRcvState != WALRCV_STREAMING as it is
> okay to have WALRCV_WAITING/STARTING/RESTARTING. But the worker should
> exit no-op only when it finds walRcvState switched back to
> WALRCV_STREAMING.
> 

Yeah, fully agree.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com