Re: Synchronizing slots from primary to standby

On Sun, Feb 11, 2024 at 6:53 PM Zhijie Hou (Fujitsu)
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> Agreed. Here is the V84 patch which addressed this.
>

Few comments:
=============
1. Isn't the new function (pg_sync_replication_slots()) allowed to
sync the slots from physical standby to another cascading standby?
Won't it be better to simply disallow syncing slots on cascading
standby to keep it consistent with slotsync worker behavior?

2.
Previously, I commented to keep the declaration and definition of
functions in the same order but I see that it still doesn't match in
the below case:

@@ -44,6 +46,7 @@ extern void WalSndWakeup(bool physical, bool logical);
extern void WalSndInitStopping(void);
extern void WalSndWaitStopping(void);
extern void HandleWalSndInitStopping(void);
+extern XLogRecPtr GetStandbyFlushRecPtr(TimeLineID *tli);
extern void WalSndRqstFileReload(void);

I think we can keep the new declaration just before WalSndSignals().
That would be more consistent.

3.
+ <para>
+ True if this is a logical slot that was synced from a primary server.
+ </para>
+ <para>
+ On a hot standby, the slots with the synced column marked as true can
+ neither be used for logical decoding nor dropped by the user. The value

I don't think we need a separate para here.

Apart from this, I have made several cosmetic changes in the attached.
Please include these in the next version unless you see any problems.

--
With Regards,
Amit Kapila.