Re: PSQL Data Type: text vs. varchar(n)

On Thursday 30 March 2006 21:27, Tom Lane wrote:
> Chris <dmagick(at)gmail(dot)com> writes:
> > kurt _ wrote:
> >> My question: Is a text field just a varchar(Integer.MAX_VALUE)?
> >
> > varchar has a max of 255 characters,
>
> You must be using some other database ;-)
>
> The current Postgres code has a physical limit of 1G bytes for any
> column value (and in practice you'll hit the threshold of pain
> performance-wise at much less than that). The only real difference
> between type "text" and type "varchar(N)" is that you'll incur runtime
> overhead checking that values assigned to varchar columns are not any
> wider than the specified "N".
>
> My own take on this is that you should "say what you mean". If you do
> not have a clear application-oriented reason for specifying a particular
> limit N in varchar(N), you have no business choosing a random value of N
> instead. Use text, instead of making up an N.

Tom, good point. However, if you design an application that at one point
_might_ need to be run on something else than postgres (say oracle or DB2),
your're way better off with a varchar than text.

UC

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