On 2013-10-25 09:26:29 -0400, Robert Haas wrote: > > In any case, it's very far from obvious to me that CLUSTER ought > > to throw away information by default, which is what you're proposing. > > I find it odd to referring to this as throwing away information. I > know that you have a general concern about throwing away XIDs that are > still needed for forensic purposes, but that is clearly the ONLY > purpose that those XIDs serve, and the I/O advantages of freezing by > default could be massive for many of our users. What's going to > happen in practice is that experienced users will simply recommend > CLUSTER FREEZE rather than plain CLUSTER, and you won't have the > forensic information *anyway*.
I think we should just apply your "preserve forensic information when freezing" patch. Then we're good to go without big arguments ;)
Ok, here's a recap on the thread as I see it now.
1. Thomas wrote the patch with the idea that FREEZE could be an option for cluster to freeze the tuples during the cluster operation, which would save a vacuum freeze somewhere down the line. Sounds like a good idea.
2. Robert introduced the idea that this perhaps could be the default option for cluster.
3. Tom highlighted that making freeze the default would wipe out xmin values so they wouldn't be available to any forensics which might to take place in the event of a disaster.
4. Andres mentioned that we might want to wait for a patch which Robert has been working on which, currently I don't know much about but it sounds like it freezes without setting xmin to frozenXid?
5. Robert stated that he's not had much time to work on this patch due to having other commitments.
In the meantime Thomas sent in a patch which gets rid of the FREEZE option from cluster and makes it the default.
So now I'm wondering what the next move should be for this patch?
a. Are we waiting on Robert's patch to be commited before we can apply Thomas's cluster with freeze as default?
b. Are we waiting on me reviewing one or both of the patches? Which one?
I think probably it sounds safer not to make freeze the default, but then if we release 9.4 with CLUSTER FREEZE then in 9.5/10 decide it should be the default then we then have a redundant syntax to support for ever and ever.
