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From Torsten Curdt <tcu...@dff.st>
Subject Re: [ESQL] Improvement....
Date Sun, 26 Jan 2003 13:55:25 GMT
Antonio Gallardo wrote:
> Torsten Curdt dijo:
> 
>>>WHAT IS WRONG?
>>>
>>>In example A all is OK.
>>>
>>>In example B we are not using the power of the Database Manager.
>>>
>>>WHY?
>>>
>>>The LIMIT clause was designed to tell the database engine:
>>>
>>>"Let find just X rows", then the database engine when it got the X
>>>rows stop searching and return the X rows. It improves the response
>>>time, since does not to continue searching!
>>>
>>>Now think in a 10 million row table and YOU KNOW you need only 5 rows!
>>
>>whether 10 million rows or not - the current sollution will only ask for
>> 6 - one additional row. Is that the time penalty you are talking about?
> 
> 
> Yes, because you already know that there are only 5 rows for every
> register. Then the database will search the last 6th row that no exist.
> Forcing to searh in the ENTIRE table.

No - why do you think the database searches the entire table?!?
...this is just a restriction on the resultset!
--
Torsten


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