maria-discuss team mailing list archive

[Justin Swanhart <greenlion@xxxxxxxxx>]

No, you have to look in the leaf!

On Mon, Jun 22, 2015 at 7:43 PM, Roberto Spadim <roberto@xxxxxxxxxxxxx>
wrote:

> 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@xxxxxxxxx>:
>
>> 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@xxxxxxxxx>
>> 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@xxxxxxxxxxxxx>
>>> 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
>