On 06/07/2013 08:56 PM, Heikki Linnakangas wrote: > On 07.06.2013 21:33, Simon Riggs wrote: >> Now that I consider Greg's line of thought, the idea we focused on >> here was about avoiding freezing. But Greg makes me think that we may >> also wish to look at allowing queries to run longer than one epoch as >> well, if the epoch wrap time is likely to come down substantially. >> >> To do that I think we'll need to hold epoch for relfrozenxid as well, >> amongst other things. > > The biggest problem I see with that is that if a snapshot can be older > than 2 billion XIDs, it must be possible to store XIDs on the same > page that are more than 2 billion XIDs apart. It could be possible to recognise the situation and save the new XIDs on *another* page ?
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