On Wed, Oct 17, 2012 at 1:36 PM, Rick Debay <rdebay@...> wrote:

> So to summarize, the only two things key ordering affects (excluding the
> ability to use partial key matches):
>
> Less unique keys first reduce index size.
>

Right.

> More unique keys first improve garbage collection in pre 2.0 servers.
>

Obviously I wasn't clear. If you have a compound key, the selectivity of
the whole key makes a difference in garbage collection, so it doesn't make
any different whether the more selective or less selective is first. One
of the hacks to make a non-selective index behave better in pre-2.0 indexes
is to append the primary key.

Good luck,

Ann


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