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List:       mysql
Subject:    Re: Why are compiled queries 50% slower than parsed queries
From:       Sasha Pachev <sasha () surveyz ! com>
Date:       2004-04-30 3:29:12
Message-ID: 4091C808.5040509 () surveyz ! com
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Kevin Cowley wrote:
> OK
> 
> I've just been completing some benchmarking comparing compiled queries (new
> in 4.1.1 and above) with standard parsed queries.
> 
> For both INSERT  queries "insert into table( col1, col2,col3) values(?,?,?)"
> and SELECT queries "select col1, col2,col3 where col1 between ? and ?" the
> compile query is 50% slower
> 
> Parsed :-
> 
> Insert
>                   total     average      mean      mean     max       min
> run  records      time       time        time    records    time      time
>   0    24851    7.610451   0.000306   0.000239     1008   105588.000000
> 231.000000
> 
> Select
> 
>               run 0     average
> query  rows   time        time  
>     0   61  0.075193   0.007519
>     1    7  0.049296   0.004930
>     2   41  0.092106   0.009211
>     3    9  0.048571   0.004857
>     4   16  0.048425   0.004843
>     5   62  0.092040   0.009204
>     6    6  0.066477   0.006648
>     7    1  0.280004   0.028000
>     8    8  0.047900   0.004790
>     9    4  0.113344   0.011334
>    10    0  0.214862   0.021486
>    11    0  0.140650   0.014065
>    12    1  0.251094   0.025109
>    13    0  0.123815   0.012382
>    14    0  0.133870   0.013387
>    15    6  0.306981   0.030698
>    16    0  0.074054   0.007405
>    17    0  0.095875   0.009588
>    18    1  0.126500   0.012650
>    19    8  0.109567   0.010957
> 
> 
> Compiled :-
> 
> Insert
>                   total     average      mean      mean     max       min
> run  records      time       time        time    records    time      time
>   0    24851   18.224807   0.000733   0.000506     1117   303256.000000
> 438.000000
> 
> Select
>               run 0     average
> query  rows   time        time  
>     0    0  0.086140   0.086140
>     1    0  0.062718   0.062718
>     2    0  0.109377   0.109377
>     3    0  0.062499   0.062499
>     4    0  0.062543   0.062543
>     5    0  0.109723   0.109723
>     6    0  0.085447   0.085447
>     7    0  0.132177   0.132177
>     8    0  0.062524   0.062524
>     9    0  0.133001   0.133001
>    10    0  0.526721   0.526721
>    11    0  0.525792   0.525792
>    12    0  0.524818   0.524818
>    13    0  0.133818   0.133818
>    14    0  0.525871   0.525871
>    15    0  0.527045   0.527045
>    16    0  0.085946   0.085946
>    17    0  0.108599   0.108599
>    18    0  0.526602   0.526602
>    19    0  0.119850   0.119850
> 
> Anyone care to shed some light on this?

Kevin:

First, check your code to make sure that you actually prepare once, and then run 
many times, rather than prepare each time. If that is indeed the case, send your 
code to MySQL developers and have them check out the performance bug.


-- 
Sasha Pachev
Create online surveys at http://www.surveyz.com/

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