Re: [PATCH] Covering SPGiST index

>
> On a first glance the whole concept of non-multicolumn index with included
> attributes seems...well, just difficult to understand.
> But I expect for SP-GiST this must be single key with multiple included
> attributes, right?
> I couldn't find a test that checks impossibility of on 2-column SP-GiST,
> only few asserts about it. Is this checked somewhere else?
>

Yes, SpGist is by its construction a single-column index, there is no such
thing like 2-column SP-GiST yet. In the same way like original SpGist will
refuse to add a second key column, this remains after modification as well,
with exception of columns attached by INCLUDE directive. They can be
(INDEX_MAX_KEYS -1) pieces and they will not be used to create additional
index trees (as there is only one), they will be just attached to the key
tree leafs tuple.

I also little bit corrected error reporting for the case when user wants to
invoke index build with not one column. Thanks!

--
Best regards,
Pavel Borisov

Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>