Re: Why do we allow indexes to contain the same column more than once?

Hi,

On 2014-05-01 13:55:46 +0100, Greg Stark wrote:
> Is there some use case for that I'm not seeing?
> 
> postgres=***# create index tti on
> tt(i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i,i);
> CREATE INDEX
> Time: 15.891 ms

Can be useful if different opclasses are used for the individual
columns. Other than that I am not seing much use.
But what would we gain by prohibiting it except possibly breaking
people's upgrades?

Greetings,

Andres Freund