Re: ask for review of MERGE

From: Boxuan Zhai <bxzhai2010(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Greg Smith <greg(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: ask for review of MERGE
Date: 2010-10-20 01:20:13
Message-ID: AANLkTikg1jSBAY+tQQi=xP1fBbwLgHms9HawsH6wZ0_M@mail.gmail.com
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Hi,

I considered the empty source table situation again. I think it is correct
to upsert nothing in this case.

Back to the original logic of MERGE command, it is main purpose is to add
the supplementary data from the source table into the target table. Thus, an
empty source table means no input data is available, so no upsert is needed
in target table.

Regards,
Boxuan

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