yeap, i just want know if the unique allow stop the conquer at first result (unique key) or if it continue (non unique key) 2015-06-22 23:42 GMT-03:00 Justin Swanhart <greenlion@gmail.com>:
Hi,
b+tree search is binary search, which is divide and conquer. Saving scanning a key is like sneezing in a hurricane, you still are o(log(n)) in.
On Mon, Jun 22, 2015 at 7:39 PM, Justin Swanhart <greenlion@gmail.com> wrote:
Hi,
If you do a code inspection you will find that uniqueness is checked on insertion, and the database cares not about it after that.
--Justin
On Mon, Jun 22, 2015 at 7:20 PM, Roberto Spadim <roberto@spadim.com.br> wrote:
and there's optimization with this flag? i see that equal could be optimized cause if we found 1 row we can return to user that row and stop select
in other words, if i see a index with primary key or unique columns, could i change the index to unique and get some kind of performace? today i think not ,cause unique key check if it's really unique (for example at insert/update/replace), i'm wrong?
-- Roberto Spadim SPAEmpresarial - Software ERP Eng. Automação e Controle