Horton

Re: support for MERGE

Japin Li <japinli@hotmail.com>

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From: Japin Li <japinli@hotmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>, Simon Riggs <simon.riggs@enterprisedb.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Zhihong Yu <zyu@yugabyte.com>, Daniel Westermann <dwe@dbi-services.com>, Amit Langote <amitlangote09@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, Erik Rijkers <er@xs4all.nl>, Jaime Casanova <jcasanov@systemguards.com.ec>
Date: 2022-01-21T06:47:25Z
Lists: pgsql-hackers 
On Fri, 21 Jan 2022 at 05:06, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> Here's v8 of this patch.  I have fixed the problems pointed out by Jaime
> and Erik, as well as incorporated Zhihong, Erik and Justin's
> documentation fixes (typos and otherwise).
>
> Not yet included: a fix for Peter's suggestion to raise a good error
> when both tables use the same name.
>
> Individual changes can also be seen in 
> https://github.com/alvherre/postgres/commits/merge-15

+               /*
+                * NOT MATCHED actions can't see target relation, but they can see
+                * source relation.
+                */
+               Assert(mergeWhenClause->commandType == CMD_INSERT ||
+                          mergeWhenClause->commandType == CMD_DELETE ||
+                          mergeWhenClause->commandType == CMD_NOTHING);
+               setNamespaceVisibilityForRTE(pstate->p_namespace,
+                                                                        targetRelRTE, false, false);
+               setNamespaceVisibilityForRTE(pstate->p_namespace,
+                                                                        sourceRelRTE, true, true);

Should we remove the CMD_DELETE from Assert(), since it will not happened
according to MERGE syntax?

-- 
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.

Commits

  1. Doc fixes for MERGE statement

  2. MERGE docs adjustments

  3. Link to MVCC docs in MERGE docs

  4. Fix EXPLAIN MERGE output when no tuples are processed

  5. Make EXPLAIN MERGE output format more compact

  6. Add support for MERGE SQL command

  7. Split ExecUpdate and ExecDelete into reusable pieces

  8. Add API of sorts for transition table handling in trigger.c

  9. Represent Lists as expansible arrays, not chains of cons-cells.