On Mon, Jun 21, 2004 at 10:28:59PM -0400, Tom Lane wrote: > Alvaro Herrera <[EMAIL PROTECTED]> writes:
> > This is tricky because chunks are prepended to the queue, but it also > > means we can stop processing as soon as a message belongs to another > > transaction. > > AFAIR there isn't any essential semantics to the ordering of the queue > entries, so you can probably get away with reordering if that makes life > any easier. > > Also, rather than labeling each entry individually, it might be better > to keep a separate list for each level of transaction. Then instead of > relabeling, you'd just concat the subtrans list to its parent's. Seems > like this should be faster and less storage. Right, but it makes harder to detect when a duplicate relcache entry is going to be inserted. Judging from the commentary in the file this is an issue. Another idea I had was: 1. at subtransaction start, add a special "boundary" message carrying the new Xid. 2. at subtransaction abort, process the first chunk backwards until the boundary message with the corresponding Xid is found; if it's not, jump to the next and repeat. At subtransaction commit nothing special needs to be done. This avoids having to label each message and to change the message appending scheme. -- Alvaro Herrera (<alvherre[a]dcc.uchile.cl>) "The eagle never lost so much time, as when he submitted to learn of the crow." (William Blake) ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
