Message-ID: <11813468-1a48-46e3-85b8-ce584b822b0b@gmail.com>
Date: Thu, 7 Dec 2023 10:27:18 +0100
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Subject: Re: Synchronizing slots from primary to standby
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To: shveta malik <shveta.malik@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>,
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From: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
In-Reply-To: <CAJpy0uBa7XHiEW_-J+0CWnFnB9EbUG6MKeSTHPaCvSX2L_su5A@mail.gmail.com>
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Hi,

On 12/7/23 10:07 AM, shveta malik wrote:
> On Thu, Dec 7, 2023 at 1:19 PM Drouvot, Bertrand
> <bertranddrouvot.pg@gmail.com> wrote:
>> Might be worth to add comments in the code (around the WalRcv->latestWalEnd
>> checks) that no "lagging" sync are possible if the walreceiver is not started
>> though?
>>
> 
> I am a bit confused. Do you mean as a TODO item? Otherwise the comment
> will be opposite of the code we are writing.

Sorry for the confusion: what I meant to say is that
synchronization (should it be lagging) is not possible if the walreceiver is not started
(as XLogRecPtrIsInvalid(WalRcv->latestWalEnd) would be true).

More precisely here (in synchronize_slots()):

     /* The primary_slot_name is not set yet or WALs not received yet */
     SpinLockAcquire(&WalRcv->mutex);
     if (!WalRcv ||
         (WalRcv->slotname[0] == '\0') ||
         XLogRecPtrIsInvalid(WalRcv->latestWalEnd))
     {
         SpinLockRelease(&WalRcv->mutex);
         return naptime;
     }

Regards,

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