Re: Covering Indexes

On 17 July 2012 16:54, David E. Wheeler <david@justatheory.com> wrote:
> Yeah, but that index is unnecessarily big if one will never use c or d in the search. The nice thing about covering indexes as described for SQLite 4 and implemented in MSSQL is that you can specify additional columns that just come along for the ride, but are not part of the indexed data:
>
>     CREATE INDEX cover1 ON table1(a,b) COVERING(c,d);
>
> Yes, you can do that by also indexing c and d as of 9.2, but it might be nice to be able to include them in the index as additional row data without actually indexing them.

Can you explain what you mean by "without actually indexing them"?
ISTM that it is a non-feature if the index is already non-unique, and
the difference is simply down to the amount of snake oil applied to
the descriptive text on the release notes.