Re: A modest proposal for a FAQ addition

Tom Lane wrote:
> Q: Why do I get strange results with a CHAR(n) field?
>
> A. Don't use CHAR(n).  VARCHAR(n) has the behavior you are probably
> expecting; on top of which it's more compact and usually faster.
>
>
> I suppose the above needs some fleshing out, but man am I getting tired
> of explaining about significant vs non-significant trailing blanks.

OK, good point.  I was mentioning CHAR() in the FAQ entry first, while
it should have been mentioned later.  I also added a specific mention of
the trailing spaces issue.  Patch attached.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
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*** FAQ.html    Sun Jan 12 00:15:28 2003
--- /bjm/FAQ.html    Sun Jan 12 00:15:25 2003
***************
*** 1052,1066 ****
      stored out-of-line by <SMALL>TOAST</SMALL>, so the space on disk
      might also be less than expected.</P>

!     <SMALL>VARCHAR(n)</SMALL> is best when storing variable-length
!     strings but it limits how long a string can be. <SMALL>TEXT</SMALL>
!     is for strings of unlimited length, maximum 1 gigabyte.
!     <P><SMALL>CHAR(n)</SMALL> is for storing strings that are all the
!     same length. <SMALL>CHAR(n)</SMALL> stores trailing spaces, while
!     <SMALL>VARCHAR(n)</SMALL> trims them. <SMALL>BYTEA</SMALL> is for
!     storing binary data, particularly values that include
!     <SMALL>NULL</SMALL> bytes. These types have similar performance
!     characteristics.</P>

      <H4><A name="4.15.1">4.15.1</A>) How do I create a
      serial/auto-incrementing field?</H4>
--- 1052,1064 ----
      stored out-of-line by <SMALL>TOAST</SMALL>, so the space on disk
      might also be less than expected.</P>

!     <P><SMALL>CHAR(n)</SMALL> is best when storing strings that are
!     usually the same length. <SMALL>VARCHAR(n)</SMALL> is best when
!     storing variable-length strings but it limits how long a string can
!     be. <SMALL>TEXT</SMALL> is for strings of unlimited length, maximum
!     1 gigabyte. <SMALL>BYTEA</SMALL> is for storing binary data,
!     particularly values that include <SMALL>NULL</SMALL> bytes. These
!     types have similar performance characteristics.</P>

      <H4><A name="4.15.1">4.15.1</A>) How do I create a
      serial/auto-incrementing field?</H4>