Re: Transactions involving multiple postgres foreign servers

On Mon, Sep 26, 2016 at 5:25 PM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> On Mon, Sep 26, 2016 at 7:28 PM, Ashutosh Bapat
> <ashutosh.bapat@enterprisedb.com> wrote:
>> My original patch added code to manage the files for 2 phase
>> transactions opened by the local server on the remote servers. This
>> code was mostly inspired from the code in twophase.c which manages the
>> file for prepared transactions. The logic to manage 2PC files has
>> changed since [1] and has been optimized. One of the things I wanted
>> to do is see, if those optimizations are applicable here as well. Have
>> you considered that?
>>
>>
>
> Yeah, we're considering it.
> After these changes are committed, we will post the patch incorporated
> these changes.
>
> But what we need to do first is the discussion in order to get consensus.
> Since current design of this patch is to transparently execute DCL of
> 2PC on foreign server, this code changes lot of code and is
> complicated.

Can you please elaborate. I am not able to understand what DCL is
involved here. According to [1], examples of DCL are GRANT and REVOKE
command.

> Another approach I have is to push down DCL to only foreign servers
> that support 2PC protocol, which is similar to DML push down.
> This approach would be more simpler than current idea and is easy to
> use by distributed transaction manager.

Again, can you please elaborate, how that would be different from the
current approach and how does it simplify the code.

-- 
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company