Re: Proposal: Select ... AS OF Savepoint - Mailing list pgsql-hackers

From Gokulakannan Somasundaram
Subject Re: Proposal: Select ... AS OF Savepoint
Date
Msg-id 9362e74e0711020521j5d1d73dduaacd2595ff459081@mail.gmail.com
Whole thread Raw
In response to Re: Proposal: Select ... AS OF Savepoint  ("Jonah H. Harris" <jonah.harris@gmail.com>)
Responses Re: Proposal: Select ... AS OF Savepoint  (Hans-Juergen Schoenig <postgres@cybertec.at>)
List pgsql-hackers


On 11/2/07, Jonah H. Harris <jonah.harris@gmail.com> wrote:
On 11/2/07, Gokulakannan Somasundaram <gokul007@gmail.com> wrote:
> If the proposal is implemented
> BEGIN
>
> savepoint s1;
>
> some DML operations
>
> get current inventory2 = select ...
>
> if current inventory2 is < fixed size
>     current inventory1 = select .. as of savepoint s1;
> END
>
> Do you see the difference?

Yes, a completely non-standard and somewhat unusual feature.  What I
don't see is why you're wasting time pushing this frankly obscure idea
for time-travel, "only within a transaction".  Why not just go all out
and suggest re-adding time-travel completely.

I think Simon Riggs is already working on that idea. This one is fairly easy to implement. I think these are some of the features only a time-stamp based database can implement. I think database standards were formed during the time, when the data consistency was provided with Lock based mechanisms. And moreover i have already committed on the indexes with snapshot and i am still waiting for its approval from hackers. If that does go through, then i need to work on the reverse mapping hash tables, which is really a long task. So i may not be able to take  up  time-travel now.

--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation                | fax: 732.331.1301
499 Thornall Street, 2nd Floor          | jonah.harris@enterprisedb.com
Edison, NJ 08837                        | http://www.enterprisedb.com/



--
Thanks,
Gokul.
CertoSQL Project,
Allied Solution Group.
(www.alliedgroups.com)

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