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From Michael McCandless <>
Subject Re: Enhance SnapshotDeletionPolicy to allow taking multiple snapshots
Date Tue, 27 Apr 2010 14:54:58 GMT
This would be great!

I think we should just enhance SDP rather than make a new MDP.


On Tue, Apr 27, 2010 at 9:59 AM, Shai Erera <> wrote:
> Hi
> Today, SnapshotDeletionPolicy (SDP) allows taking only one snapshot. I need
> to be able to take multiple snapshots. Consider multiple processes doing
> several things on the index - each needs a snapshot of the index so that
> commit it needs doesn't get deleted under the covers. SDP is perfect, only
> it allows for only one snapshot. So I was thinking to extend it to a
> MultiSDP which adds an 'id' parameter to snapshot() and release(). But then,
> I was thinking - why shouldn't that exist in SDP? It won't make the API
> anymore complicated, and in addition won't introduce yet another DP class.
> This can be done in two ways:
> 1) snapshot() and release() get the extra parameter. For convenience we can
> allow for a null id, in which case only one snapshot w/ a null id can be
> taken (until it's released). To avoid making up an id if you really need a
> single snapshot.
> 2) add variants snapshot() and release() which take an id as argument. Or
> ... extend SDP to MultiSDP.
> I'd prefer if we keep that functionality in SDP, but if you prefer an
> extension to it, then we'll need to allow for easier extension of SDP (I
> think we should do that anyway).
> What do you think?
> Shai

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