Re: Proposal: Snapshot cloning

On 1/26/2007 8:06 AM, Gregory Stark wrote:
> "Jan Wieck" <JanWieck@Yahoo.com> writes:
> 
>>     backend1: select publish_snapshot(); -- will block
>>
>>     backend2: start transaction;
>>     backend2: set transaction isolation level serializable;
>>     backend2: select clone_snapshot(<pid>); -- will unblock backend1
> 
> It seems simpler to have a current_snapshot() function that returns an bytea
> or a new snapshot data type which set_current_snapshot(bytea) took to change
> your snapshot. Then you could use tables or out-of-band communication to pass
> around your snapshots however you please. 
> 
> set_current_snapshot() would have to sanity check that the xmin of the new
> snapshot isn't older than the current globaloldestxmin. 

That would solve the backend to backend IPC problem nicely.


Jan

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