Single-threaded Post (STP) is observed to be very slow and the Post state shows Skip records for rollback:
sp_ctrl >show post detail
Host : hostname
Source : o.SID Queue : queue_name
Operations
Target Status Posted Since Total Backlog
---------- --------------- ---------- ------------------ ---------- ----------
o.SID1 Running 7738924 11-Aug-09 17:22:54 13023273 5283873
Last operation posted:
Redo log: 499498 Log offset: 508826700
UPDATE of OWNER.TABLE_NAME at 08/11/09 16:28:35
Post state : Skip records for rollback
Activation Id : 125
Current transaction Id : 23
ID of blocking transaction : 0
.
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At times STP may not be as efficient in handling rollbacks.
Though STP may still be processing transactions, the rate may be very slow. If this is the case and if one wants to expedite it faster, one can try switching to Multi-threaded Post (MTP) and see if this helps. By switching to MTP it has been observed that such rollbacks are processed much faster and the backlog will start coming down sooner. If Post is allowed to deal with it on its own, it may be able to get past the problem in due course. It all depends on the propensity of the customer to wait for that to happen vis-à-vis interfering with it and resolving it sooner.
Some other points to note here is that this will only apply for Shareplex 5.1 (when MTP was introduced) and 5.3.STP has been deprecated in version 6.0 or up and so if the problem does occur, it will not be because of STP. It is not a foregone conclusion that setting it to MTP will always resolve it. This solution thus applies to a specific situation.
To correctly switch the mode from STP to MTP or vice versa, please refer to Solution # SOL33386 for details.
