Re: Explain Plan question

From: Brian Peasland <oracle_dba_at_peasland.com>
Date: Mon, 22 Apr 2002 21:23:00 GMT
Message-ID: <3CC47F34.59B03DEF@peasland.com>

One of the most obvious answers is that SRS.Table1 and SRS.Table2 were not in the buffer cache when query 1 ran. When queries 2 and 3 ran, the data did not have to be read from disk. It got the data straight from the buffer cache (memory) which is much, much faster. Did you try running query 1 again to see if you got an "improved" response time?

HTH,
Brian

Jayne Heger wrote:
>
> Hi,
>
> I have ran an Explain query on three quesries to test which one would be
> the most efficient to use.
>
> The 1st query, had a cost of 26
> second one = 10006
> third one = 7347
>
> Now, to my understanding, the 1st one would be the most efficient.
> But I have also ran a timer on each of the queries, and the 1st query took
> the longest time by far.
> 1st query = 00:11:58:39
> 2nd query = 00:00:08:42
> 3rd query = 00:00:08:80
>
> would it be because of the network load that the 1st query took so long?
>
> Can anyone explain this, i am a bit puzzled?
>
> Thanks
>
> Jayne
Received on Mon Apr 22 2002 - 16:23:00 CDT