Re: AS OF queries

On 12/20/2017 01:45 PM, Konstantin Knizhnik wrote:
> I wonder if Postgres community is interested in supporting time travel
> queries in PostgreSQL (something like AS OF queries in Oracle:
> https://docs.oracle.com/cd/B14117_01/appdev.101/b10795/adfns_fl.htm).
> As far as I know something similar is now developed for MariaDB.
>
> It seems to me that it will be not so difficult to implement them in
> Postgres - we already have versions of tuples.
> Looks like we only need to do three things:
> 1. Disable autovacuum (autovacuum = off)
> 2. Enable commit timestamp (track_commit_timestamp = on)
> 3. Add asofTimestamp to snapshot and patch XidInMVCCSnapshot to
> compare commit timestamps when it is specified in snapshot.
>

that sounds really awesome ... i would love to see that.
my question is: while MVCC is fine when a tuple is still there ...
what are you going to do with TRUNCATE and so on?
it is not uncommon that a table is truncated frequently. in this case
MVCC won't help.
what are your thoughts on this ?

    many thanks,

        hans

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Hans-Jürgen Schönig
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