Re: [HACKERS] MERGE SQL Statement for PG11

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] MERGE SQL Statement for PG11
Date: 2018-01-04 17:38:16
Message-ID: CANP8+jJwsoa_ys3urjBh2-fMXTcxkfYT8NwEQPMuuZBkzcV=5A@mail.gmail.com
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On 4 January 2018 at 17:29, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Sat, Dec 30, 2017 at 6:01 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> Patch uses mechanism as agreed previously with Peter G et al. on this thread.
>
> I'm not sure that an agreement was reached, or what the substance of
> that agreement was.

I refer to this... and confirm I have implemented option 3

On 3 November 2017 at 11:07, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> * Robert Haas (robertmhaas(at)gmail(dot)com) wrote:
>> On Fri, Nov 3, 2017 at 1:05 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> > We seem to have a few options for PG11
>> >
>> > 1. Do nothing, we reject MERGE
>> >
>> > 2. Implement MERGE for unique index situations only, attempting to
>> > avoid errors (Simon OP)
>> >
>> > 3. Implement MERGE, but without attempting to avoid concurrent ERRORs (Peter)
>> >
>> > 4. Implement MERGE, while attempting to avoid concurrent ERRORs in
>> > cases where that is possible.
>> >
>> > Stephen, Robert, please say which option you now believe we should pick.
>>
>> I think Peter has made a good case for #3, so I lean toward that
>> option. I think #4 is too much of a non-obvious behavior difference
>> between the cases where we can avoid those errors and the cases where
>> we can't, and I don't see where #2 can go in the future other than #4.
>
> Agreed.

--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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