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Re: doubt about index


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

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