Re: Big 7.4 items

From: Jan Wieck <JanWieck(at)Yahoo(dot)com>
To: darren(at)up(dot)hrcoxmail(dot)com
Cc: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, shridhar_daithankar(at)persistent(dot)co(dot)in, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Big 7.4 items
Date: 2002-12-13 21:31:51
Message-ID: 3DFA51C7.1113ED92@Yahoo.com
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darren(at)up(dot)hrcoxmail(dot)com wrote:
>
> > It is asynchronous without the need of 2 phase commit. It is group
> > communication based and requires the group communication system to
> > guarantee total order. The tricky part is, that the local transaction
> > must be on hold until the own commit message comes back without a prior
>
> No, It holds until it's own Writeset comes back. Commits
> and then send a commit message on the simple channel, so
> commits don't wait for ordered writesets.
>
> Remember total order guarantees if no changes in front of
> the local changes conflict, the local changes can commit.

Right, it's the writeset ... that get's sent just before you flip bits
in the clog, then wait until it comes back and flip 'em.

> >
> > The last time i was playing with spread (that was at Great Bridge in
> > Norfolk), it was IMHO useless (for Postgres-R) because it sometimes
> > dropped messages when the network load got too high. This occured
> > without any indication, no error, nothing. This is not exactly what I
> > understand as total order. I hope they have made some substantial
> > progress on that.
> >
>
> I remember the TCL tester you set up, and having problems,
> but I don't recall investigating what the problems were.
> If you still have the code I can try and reproduce the
> problem, and investigate it on the spread list.

Maybe you heard about it, there was this funny conversation while
walking down the hallway:

"Did that German guy ever turn in his notebook?"

"You mean THIS German guy?"

"Yes, did he turn it in?"

"He is here. Right BEHIND YOU!!!"

"Hummmpf ... er ..."

The stuff was on that notebook. Sorry.

Jan

--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#================================================== JanWieck(at)Yahoo(dot)com #

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