Re: COPY data into a table with a SERIAL column?

From: David G Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: COPY data into a table with a SERIAL column?
Date: 2014-10-16 17:38:15
Message-ID: 1413481095811-5823291.post@n5.nabble.com
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Steve Wampler wrote
> Let me generalize the problem a bit: How can I specify that the default
> value of a column
> is to be used with a COPY command when some rows have values for that
> column and
> some don't?

If you provide a value for a column, including NULL, the default expression
is not evaluated.

COPY is dumb but fast. If you need logic you need to add it yourself.
Either before the copy or copy into a temporary UNLOGGED table and write
smart SQL to migrate from that to the live table.

You can also put smarts into a trigger.

Personally I would generally stage all the data then write two INSERT INTO
... SELECT statements; one for the known values and one where you omit the
column and let the system use the default.

David J.

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