maria-discuss team mailing list archive

[Justin Swanhart <greenlion@xxxxxxxxx>]

you are probably thinking of b-trees which are unbalanced.  b+tree is
o(log(n)) based on depth of tree and you always have to go to bottom to get
leaf.

On Mon, Jun 22, 2015 at 7:44 PM, Justin Swanhart <greenlion@xxxxxxxxx>
wrote:

> 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
>>
>
>