Thread

1. Re: [QUESTIONS] varchar vs text

   Thomas Lockhart <lockhart@alumni.caltech.edu> — 1998-03-01T21:28:56Z

   > > > Varchar currently (in 6.2.1 and below) takes up the entire length specified
   > > > in the definition, despite the fact the value in it may actually be
   > > > shorter. Text takes only the space taken by the value.
   > >
   > > Thanks for the clarification. In this case, what happens with varchar's
   > > length if the original definition for that field leaves length undefined?
   > > Does it behave like text in that case?
   >
   > You really shouldn't be doing that.  Not sure what happens.  Not a good
   > idea:
   >
   >         create table test (x varchar);
   
   ?? This was defined to be a varchar of unlimited length, much like, or identical
   to, text. Should this now be disallowed? If so, we can fix the parser to disallow
   it so people don't get misled.
   
   > > I also vaguely recall seeing a message last year about the use of indexes
   > > in queries: that in [some circumstances] indexes built on varchar fields
   > > don't get used and a sequential scan through all records takes place
   > > instead. Is there any distinction between varchar and text here?
   >
   > Don't remember that.
   
   This was probably Bruce's improvements to allow indices on some pattern matching.
   Doesn't make a distinction between these types in its behavior.
   
                                                     - Tom
   
   
   

2. Re: [QUESTIONS] varchar vs text

   Bruce Momjian <maillist@candle.pha.pa.us> — 1998-03-01T21:39:28Z

   > 
   > > > > Varchar currently (in 6.2.1 and below) takes up the entire length specified
   > > > > in the definition, despite the fact the value in it may actually be
   > > > > shorter. Text takes only the space taken by the value.
   > > >
   > > > Thanks for the clarification. In this case, what happens with varchar's
   > > > length if the original definition for that field leaves length undefined?
   > > > Does it behave like text in that case?
   > >
   > > You really shouldn't be doing that.  Not sure what happens.  Not a good
   > > idea:
   > >
   > >         create table test (x varchar);
   > 
   > ?? This was defined to be a varchar of unlimited length, much like, or identical
   > to, text. Should this now be disallowed? If so, we can fix the parser to disallow
   > it so people don't get misled.
   
   Oh, I didn't know.  There really is no difference between varchar with
   no lenght, and text, but if it doesn't break anything, no problem.
   
   > 
   > > > I also vaguely recall seeing a message last year about the use of indexes
   > > > in queries: that in [some circumstances] indexes built on varchar fields
   > > > don't get used and a sequential scan through all records takes place
   > > > instead. Is there any distinction between varchar and text here?
   > >
   > > Don't remember that.
   > 
   > This was probably Bruce's improvements to allow indices on some pattern matching.
   > Doesn't make a distinction between these types in its behavior.
   
   Not sure what to say on this.  I remember that issue, but not how it
   caused any problem.
   
   -- 
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