RE: Slow catchup of 2PC (twophase) transactions on replica in LR

Dear Peter,

Thanks for reviewing! The patch will be posted in the upcoming post.

> ======
> src/backend/access/transam/twophase.c
> 
> 1. IsTwoPhaseTransactionGidForSubid
> 
> +/*
> + * IsTwoPhaseTransactionGidForSubid
> + * Check whether the given GID is formed by TwoPhaseTransactionGid.
> + */
> +static bool
> +IsTwoPhaseTransactionGidForSubid(Oid subid, char *gid)
> 
> I think the function comment should mention something about 'subid'.
> 
> SUGGESTION
> Check whether the given GID (as formed by TwoPhaseTransactionGid) is
> for the specified 'subid'.

Fixed.

> src/backend/commands/subscriptioncmds.c
> 
> 2. AlterSubscription
> 
> + if (!opts.twophase &&
> + form->subtwophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED
> &&
> + LookupGXactBySubid(subid))
> + /* Add error message */
> + ereport(ERROR,
> + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
> + errmsg("cannot disable two_phase when uncommitted prepared
> transactions present"),
> + errhint("Resolve these transactions and try again")));
> 
> The comment "/* Add error message */" seems unnecessary.

Yeah, this was an internal flag. Removed.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED
https://www.fujitsu.com/