Re: Speedup twophase transactions

On 27 January 2017 at 15:37, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 27 January 2017 at 09:59, Nikhil Sontakke <nikhils@2ndquadrant.com> wrote:
>>>> But, I put the recovery process and the checkpointer process of the
>>>> standby under gdb with breakpoints on these functions, but both did
>>>> not hit CreateRestartPoint() as well as CheckPointGuts() when I issued
>>>> a promote :-|
>>>
>>> No end-of-recovery checkpoints happen at promotion since 9.3. You can
>>> still use fallback_promote as promote file to trigger the pre-9.2 (9.2
>>> included) behavior.
>>
>> Ok, so that means, we also need to fsync out these 2PC XIDs at promote
>> time as well for their durability.
>
> Why?

The xact_redo code will add prepared transactions to the
KnownPreparedList in memory. Earlier it used to create the on-disk 2PC
file.

At standby promote, the surviving (yet uncommitted) prepared
transactions from KnownPreparedList need to be persisted, right?

Regards,
Nikhils