Hi,
On 4/3/23 7:35 AM, Amit Kapila wrote:
On Mon, Apr 3, 2023 at 4:26 AM Jeff Davis <pg...@j-davis.com> wrote:
On Fri, 2023-03-31 at 02:50 -0700, Jeff Davis wrote:
But if the ConditionVariableEventSleep() API is added, then I think
we
should change the non-recovery case to use a CV as well for
consistency, and it would avoid the need for WalSndWakeup().
It seems like what we ultimately want is for WalSndWakeup() to
selectively wake up physical and/or logical walsenders depending on the
caller. For instance:
WalSndWakeup(bool physical, bool logical)
The callers:
* On promotion, StartupXLog would call:
- WalSndWakeup(true, true)
* XLogFlush/XLogBackgroundFlush/XLogWalRcvFlush would call:
- WalSndWakeup(true, !RecoveryInProgress())
* ApplyWalRecord would call:
- WalSndWakeup(switchedTLI, switchedTLI || RecoveryInProgress())
There seem to be two approaches to making that work:
1. Use two ConditionVariables, and WalSndWakeup would broadcast to one
or both depending on its arguments.
2. Have a "replicaiton_kind" variable in WalSnd (either set based on
MyDatabaseId==InvalidOid, or set at START_REPLICATION time) to indicate
whether it's a physical or logical walsender. WalSndWakeup would wake
up the right walsenders based on its arguments.
#2 seems simpler at least for now. Would that work?
Agreed, even Bertrand and myself discussed the same approach few
emails above. BTW, if we have this selective logic to wake
physical/logical walsenders and for standby's, we only wake logical
walsenders at the time of ApplyWalRecord() then do we need the new
conditional variable enhancement being discussed, and if so, why?
Thank you both for this new idea and discussion. In that case I don't think
we need the new CV API and the use of a CV anymore. As just said up-thread I'll
submit
a new proposal with this new approach.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
