Re: single index on more than two coulumns a bad thing?

--On fredag, april 02, 2004 09.56.04 -0600 Bruno Wolff III <bruno(at)wolff(dot)to>
wrote:

> On Fri, Apr 02, 2004 at 01:00:45 +0200,
> Palle Girgensohn <girgen(at)pingpong(dot)net> wrote:
>>
>> Is it always bad to create index xx on yy (field1, field2, field3);
>>
>> I guess the problem is that the index might often grow bigger than the
>> table, or at least big enough not to speed up the queries?
>
> One place where you need them in postgres is enforcing unique multicolumn
> keys. These will get created implicitly from the unique (or primary key)
> constraint. It isn't all that unusual to have a table that describes
> a many to many (to many ...) relationship where the primary key is all
> of the columns.

True, of course!

/Palle