On Wed, Feb 14, 2018 at 8:44 AM, Clemens Ladisch <clem...@ladisch.de> wrote:

> Dominique Devienne wrote:
> > in https://www.sqlite.org/src/info/f3112e67cdb27c1a
> > to fix above ticket, I see queries with order by +a,
> > but in https://www.sqlite.org/lang_select.html#orderby
> > I don't see any obvious mention about that +.
>
> "Unary plus" does not change the value:
>
>   sqlite> select 1;
>   1
>   sqlite> select -1;
>   -1
>   sqlite> select +1;
>   1
>
> It's used to change the expression from a column reference to something
> that is computed, which means that SQLite cannot use an index for it
> (unless you created an expression index on +a):
> <http://www.sqlite.org/optoverview.html#uplus>


Thanks. That's interesting. But then, why use it in this context?
Why DRH wants to purposely bypass the index in this case?
How is that relevant to testing tuple / row-values comparisons? --DD
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