Re: Proposal: Snapshot cloning

On 1/26/2007 8:06 AM, Gregory Stark wrote:
> "Jan Wieck" <JanWieck(at)Yahoo(dot)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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