Tuple visibility within a single XID - Mailing list pgsql-hackers

From Jim Nasby
Subject Tuple visibility within a single XID
Date
Msg-id 55247D6E.3030906@BlueTreble.com
Whole thread Raw
Responses Re: Tuple visibility within a single XID
List pgsql-hackers
My understanding is that all subtransactions get their own unique XID 
(assuming they need one), and that CommandId can't move backwards within 
a transaction. If that's correct, then shouldn't we be able to prune 
tuples where XMIN and XMAX match our *exact* XID (not all the extra 
stuff that TransactionIdIsCurrentTransactionId() does) and CommandId < 
CurrentCommandId?

I thought of this because of a post to -general. It's certainly not a 
common case, but it seems like there's not much downside...
-- 
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com



pgsql-hackers by date:

Previous
From: Fabrízio de Royes Mello
Date:
Subject: Re: Doubt about AccessExclusiveLock in ALTER TABLE .. SET ( .. );
Next
From: Peter Geoghegan
Date:
Subject: Re: Tuple visibility within a single XID