From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Francisco Reyes <lists(at)natserv(dot)com> |
Cc: | pgsql General List <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: |
Date: | 2002-07-04 18:38:31 |
Message-ID: | 200207041838.g64IcVI26416@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-general |
Francisco Reyes wrote:
> On the FAQ we have:
>
> CHAR() is best when storing strings that are usually the
> same length. VARCHAR() is best when storing variable-length strings,
> but you want to limit how long a string can be. TEXT is for strings
> of unlimited length, maximum 1 gigabyte. BYTEA is for storing
> binary data, particularly values that include NULL bytes.
>
>
> How much space does "NULL" takes on a varchar.
Zero space. We have a bitmask of NULL columns for every row.
> I have a table where possibly less than 40% of the records will have a
> value. I am wondering if I should go with a second table for those that
> have the values or if NULL is small enough that it won't be much an
> overhead for the possibly 60% instances when the column would be empty.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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