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Re: NOLOGGING option, or ?

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Alon Goldshuv <agoldshuv(at)greenplum(dot)com>
Cc: Luke Lonergan <llonergan(at)greenplum(dot)com>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: NOLOGGING option, or ?
Date: 2005-06-02 01:01:56
Message-ID: 200506020101.j5211uj02770@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Alon Goldshuv wrote:
> Bruce,
> 
> The patch is not there to show that something is "broken" is it there to
> show how things could be done in another way, which may or may not be more
> desireable.

Sure, we are always looking for ways to improve things.

> > COPY works as designed.  The idea that some guy we have never heard of
> > is going to appear and rewrite COPY's processing and tell us that the
> > existing code is actually broken seems pretty arrogant to me.  If it is
> > broken (meaning doesn't work as designed), please show us facts rather
> > than conjecture.
> 
> I am sure that the code works as designed. In my previous email I was
> referring to the fact that using COPY with a data field that happens to have
> backslashes in it, and then querying this data field you will get different
> results. For example do COPY of a field "c:\\one\ten\nine" and query for it.
> The result will be much different. This is a problem with clickstream data
> for example. That's all. It's very possible that there are reasons that I
> missed for why things are the way they are.

Yep, you have to double backslahses coming in as data so we can use
backslash for marking null, delimiters, etc.  I see no way around that,
and no one since Berkeley has come up with one either.  If you have an
idea, we would _love_ to hear it.

> > (Please explain how you handle literal delimiters and nulls with no
> > escape processing.)
> Escape processing is done only for these 2 cases.

OK, how is that done?  How about for newlines in the data?  

Right now I think that is the only escapes we do. We support more but
basically the only required ones are delimiter and nulls.  The others
are around just for convenience.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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