RE: Synchronizing slots from primary to standby - Mailing list pgsql-hackers

From Zhijie Hou (Fujitsu)
Subject RE: Synchronizing slots from primary to standby
Date
Msg-id OS0PR01MB5716AB56177CDE559109238B94232@OS0PR01MB5716.jpnprd01.prod.outlook.com
Whole thread Raw
In response to Re: Synchronizing slots from primary to standby  (Bertrand Drouvot <bertranddrouvot.pg@gmail.com>)
List pgsql-hackers
On Monday, March 4, 2024 7:22 PM Bertrand Drouvot <bertranddrouvot.pg@gmail.com> wrote:
>
> Hi,
>
> On Sun, Mar 03, 2024 at 07:56:32AM +0000, Zhijie Hou (Fujitsu) wrote:
> > Here is the V104 patch which addressed above and Peter's comments.
>
> Thanks!
>
> A few more random comments:

Thanks for the comments!

>
> 1 ===
>
> +        The function may be blocked if the specified slot is a failover
> + enabled
>
> s/blocked/waiting/ ?

Changed.

>
> 2 ===
>
> +                * specified slot when waiting for them to catch up. See
> +                * StandbySlotsHaveCaughtup for details.
>
> s/StandbySlotsHaveCaughtup/StandbySlotsHaveCaughtup()/ ?

Changed.

>
> 3 ===
>
> +       /* Now verify if the specified slots really exist and have
> + correct type */
>
> remove "really"?

Changed.

>
> 4 ===
>
> +       /*
> +        * Don't need to wait for the standbys to catch up if there is no value in
> +        * standby_slot_names.
> +        */
> +       if (standby_slot_names_list == NIL)
> +               return true;
> +
> +       /*
> +        * Don't need to wait for the standbys to catch up if we are on a
> standby
> +        * server, since we do not support syncing slots to cascading standbys.
> +        */
> +       if (RecoveryInProgress())
> +               return true;
> +
> +       /*
> +        * Don't need to wait for the standbys to catch up if they are already
> +        * beyond the specified WAL location.
> +        */
> +       if (!XLogRecPtrIsInvalid(standby_slot_oldest_flush_lsn) &&
> +               standby_slot_oldest_flush_lsn >= wait_for_lsn)
> +               return true;
>
> What about using OR conditions instead?
>
> 5 ===
>
> +static bool
> +NeedToWaitForStandby(XLogRecPtr target_lsn, XLogRecPtr flushed_lsn,
> +                                        uint32 *wait_event)
>
> Not a big deal but does it need to return a bool? (I mean it all depends of the
> *wait_event value). Is it for better code readability in the caller?
>
> 6 ===
>
> +static bool
> +NeedToWaitForWal(XLogRecPtr target_lsn, XLogRecPtr flushed_lsn,
> +                                uint32 *wait_event)
>
> Same questions as for NeedToWaitForStandby().

I also feel the current style looks a bit cleaner, so didn’t change these.

Best Regards,
Hou zj



pgsql-hackers by date:

Previous
From: Ronan Dunklau
Date:
Subject: Re: Failures in constraints regression test, "read only 0 of 8192 bytes"
Next
From: "Zhijie Hou (Fujitsu)"
Date:
Subject: RE: Synchronizing slots from primary to standby