Re: boolean over char(1)

Also, we do support "char", which is one byte. You need to specify the
quotes when creating the column.

---------------------------------------------------------------------------

Tom Lane wrote:
> "Thomas T. Thai" <tom(at)minnesota(dot)com> writes:
> > Is there any advantages of using datatype boolean over char(1)?
>
> boolean fits in 1 byte; char(1) requires 5 bytes (maybe more, depending
> on alignment considerations).
>
> boolean will be considerably faster to operate on, being pass-by-value.
>
> char(1) will happily accept values that don't correspond to booleans
> (eg, if you use 't' and 'f' to represent booleans in a char(1), what
> will you do with 'y' or 'z'?) You could possibly fix that with a
> check constraint, but that slows things down still more.
>
> boolean is, um, boolean: it behaves as expected in boolean expressions.
> You can't do AND, OR, NOT directly on chars.
>
>
> > If there isn't I think char(1) is more portable across other DBM?
>
> The boolean datatype is standard in SQL99.
>
> regards, tom lane
>
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