| From: | Nico Williams <nico(at)cryptonector(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Peter Geoghegan <pg(at)bowt(dot)ie>, Robert Haas <robertmhaas(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: MERGE SQL Statement for PG11 |
| Date: | 2017-11-02 19:39:33 |
| Message-ID: | 20171102193932.GS4496@localhost |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
If nothing else, anyone needing MERGE can port their MERGE statements to
a DML with DML-containing CTEs...
The generic mapping would be something like this, I think:
WITH
rows AS (SELECT <target> FROM <target> WHERE <condition>)
, updated AS (
UPDATE <target>
SET ...
WHERE <key> IN (SELECT <key> FROM rows) /* matched */
RETURNING <target>
)
, inserted AS (
INSERT INTO <target>
SELECT ...
WHERE <key> NOT IN (SELECT <key> FROM rows) /* not matched */
RETURNING <target>
)
DELETE FROM <target>
WHERE (...) AND
<key> NOT IN (SELECT <key> FROM updated UNION
SELECT <key> FROM inserted);
Nico
--
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