From: | yudhi s <learnerdatabase99(at)gmail(dot)com> |
---|---|
To: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> |
Cc: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, pgsql-general <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Insert works but fails for merge |
Date: | 2024-08-10 20:23:11 |
Message-ID: | CAEzWdqfLi-JtgZPhArq-6hAcSe9RnjN62LbeS8rVVSAiQOiOtg@mail.gmail.com |
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Lists: | pgsql-general |
On Sat, Aug 10, 2024 at 8:22 PM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:
>
>
> Why not use INSERT ... ON CONFLICT instead of MERGE?
>
> >
> > MERGE INTO tab1 AS target
> > USING (VALUES ('5efd4c91-ef93-4477-840c-a723ae212d99', 123,
> > '2024-08-09T11:33:49.402585600Z','2024-08-09T11:33:49.402585600Z')) AS
> > source(id, mid,txn_timestamp, cre_ts)
> > ON target.id <http://target.id> = source.id <http://source.id>
> > WHEN MATCHED THEN
> > UPDATE SET mid = source.mid
> > WHEN NOT MATCHED THEN
> > INSERT (id, mid, txn_timestamp, cre_ts)
> > VALUES (source.id <http://source.id>,source.mid,
> > source.txn_timestamp, source.cre_ts);
>
>
>
Actually , as per the business logic , we need to merge on a column which
is not unique or having any unique index on it. It's the leading column of
a composite unique key though. And in such scenarios the "INSERT.... ON
CONFLICT" will give an error. So we are opting for a merge statement here,
which will work fine with the column being having duplicate values in it.
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