Re: Is it possible to set end-of-data marker for COPY statement.

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Junfeng Yang <yjerome(at)vmware(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Is it possible to set end-of-data marker for COPY statement.
Date: 2020-09-01 17:23:00
Message-ID: 20200901172300.GX13613@momjian.us
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On Tue, Sep 1, 2020 at 12:05:02PM -0400, Bruce Momjian wrote:
> > copy test from '/tmp/data' DELIMITER ',';
> >
> > An end-of-copy marker corrupt error will be raised.
> >
> > This requires users to escape the end-of-data marker manually in their data.
> > Why we don't have a mechanism to define other characters as end-of-data marker?
> > Or there are other ways to avoid escape the end-of-data in data?
>
> This is the first I am hearing of this. The problem is that the system
> can't decide if \. is escaping a delimiter, or the end-of-copy marker.
> I think we need to just disable period as a delimiter. I don't think
> there is enough demand to allow the end-of-data marker to be
> configurable.
>
> Interestingly, you can use period as s delimiter if you are copying from
> a file that doesn't need an end-of-data marker and you never need to
> escape the delimiter, but that seems like too rare a use case to allow
> period to be supported as a delimiter.

I am sorry I mis-read this email. The example uses _comma_ for the
delimiter, rather than period. Let me reply again. We already disallow
period for delimiters:

COPY test TO '/u/postgres/tmp/x' WITH (DELIMITER '.');
ERROR: COPY delimiter cannot be "."

COPY test TO STDOUT WITH (DELIMITER '.');
ERROR: COPY delimiter cannot be "."

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com

The usefulness of a cup is in its emptiness, Bruce Lee

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