Re: SSI and Hot Standby - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: SSI and Hot Standby
Date
Msg-id 1295604054.1803.9502.camel@ebony
Whole thread Raw
In response to Re: SSI and Hot Standby  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: SSI and Hot Standby
List pgsql-hackers
On Fri, 2011-01-21 at 11:19 +0200, Heikki Linnakangas wrote:
> On 21.01.2011 11:10, Simon Riggs wrote:
> > So any xid that commits in a different sequence to the order in which
> > the xid was assigned creates a potential for unserialization? Or?
> 
> It's not the order in which the xid was assigned that matters, but the 
> order the transactions started and got their snapshots. The xids might 
> be assigned a lot later, after the transactions have already read data.

So if a read-write transaction assigns an xid before it takes a snapshot
then we'll be OK? That seems much easier to arrange than passing chunks
of snapshot data backwards and forwards. Optionally.

-- Simon Riggs           http://www.2ndQuadrant.com/books/PostgreSQL Development, 24x7 Support, Training and Services



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