Ühel kenal päeval, K, 2007-10-10 kell 12:18, kirjutas Tom Lane:
> Magnus Hagander <magnus@hagander.net> writes:
> > (Assuming it's technically sound - I still haven't checked the actual
> > code, but I'm assuming it's Ok since Jan approved it)
>
> I hadn't looked at it either, but here are a few things that need
> review:
>
> * Why no binary I/O support for the new datatype? We tend to expect
> that for all core types.
should be easy to add, likely a copy-past from any other varlena type.
> * Why is txid_current_snapshot() excluding subtransaction XIDs? That
> might be all right for the current uses in Slony/Skytools, but it seems
> darn close to a bug for any other use.
Just thinking aloud here :
I think that the reason has something to do with it being for stored
snapshots used by different transactions for determining info about
other committed transactions , and the stored snapshots and transaction
ids become visible from SQL level only after both are committed.
There may be cases where you want to use it from other places, say C
code for user-defined function dealing with visibility of other
transactions, but before adding in subtransactions and thus possibly
bloating the storage, we should first identify such case.
Most likely it is better to just use in-backend snapshots straight from
backend internals if you dont need to store them.
> * Why is txid_current_snapshot() reading SerializableSnapshot rather
> than an actually current snap as its name suggests? This isn't just
> misleading, this will fail completely when SerializableSnapshot
> goes away, as seems likely to happen in 8.4 (and no, we won't keep it
> just because txid might want it).
Why is SerializableSnapshot going away ?
How will we do serialized isolation level in 8.4 then?
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Hannu