| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)2ndquadrant(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] MERGE SQL Statement for PG11 |
| Date: | 2018-04-03 03:01:50 |
| Message-ID: | CA+Tgmoa06tNps4AndOzwPTPAuJBbtrpVs9=zDUTo0rUj5wsJrA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Apr 2, 2018 at 10:40 PM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> On Mon, Apr 2, 2018 at 7:18 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> I did a scan through this, as I hadn't been able to keep with the thread
>> previously. Sorry if some of the things mentioned here have been
>> discussed previously. I am just reading through the patch in its own
>> order, so please excuse if there's things I remark on that only later
>> fully make sense.
>>
>>
>> later update: TL;DR: I don't think the parser / executor implementation
>> of MERGE is architecturally sound. I think creating hidden joins during
>> parse-analysis to implement MERGE is a seriously bad idea and it needs
>> to be replaced by a different executor structure.
>
> +1. I continue to have significant misgivings about this. It has many
> consequences that we know about, and likely quite a few more that we
> don't.
+1. I didn't understand from Peter's earlier comments that we were
doing that, and I agree that it isn't a good design choice.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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