Re: Prevent double entries ... no simple unique index - Mailing list pgsql-sql

Marc Mamin <M.Mamin@intershop.de> wrote:

> > 
> > Or this one:
> > 
> > test=*# create unique index on log((case when state = 0 then 0 when
> > state = 1 then 1 else null end));
> > CREATE INDEX
> > 
> > 
> > Now you can insert one '0' and one '1' - value - but no more.
> 
> Hi,
> 
> A partial index would do the same, but requires less space: 
> 
> create unique index on log(state) WHERE state IN (0,1);

Right! ;-)


Andreas
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