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General: slow find()?

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    • CommentAuthortom
    • CommentTimeMar 13th 2008
     

    Hi,

    I've done some profiling in my application, and it seems that when doing multiple subsequent find()s to the same ActiveRecord class, there's a big performance penalty for the first call.

    I'm doing 15 find() calls, each with a record ID as single argument ($this->User->find( $some_ID) ), and the timings look like this:

    fast_listing_findUser_0_time=979.326 msec
fast_listing_findUser_1_time=24.116 msec
fast_listing_findUser_2_time=24.5121 msec
fast_listing_findUser_3_time=24.1258 msec
fast_listing_findUser_4_time=24.1451 msec
fast_listing_findUser_5_time=24.122 msec
fast_listing_findUser_6_time=25.4791 msec
fast_listing_findUser_7_time=27.3218 msec
fast_listing_findUser_8_time=32.3861 msec
fast_listing_findUser_9_time=29.2711 msec
fast_listing_findUser_10_time=25.63 msec
fast_listing_findUser_11_time=24.539 msec
fast_listing_findUser_12_time=24.673 msec
fast_listing_findUser_13_time=29.3739 msec
fast_listing_findUser_14_time=27.6229 msec

    So the first call takes about 30-40 times longer than the others.

    Any idea what could be the reason for this delay?

    How may I get rid of it?

    Cheers,

    Tom

    • CommentAuthorbjmg
    • CommentTimeMar 13th 2008
     
    Hi,

    I think this is due to the fact that MySQL (and many other database management systems) uses a technique that is called query caching. So subsequent calls to the same data are served to the client right from the cache. I think you can't do anything against it. Well there is a partial solution: you could use a clustered, memory based system like MySQL Cluster. But in most cases you can improve the query processing speed by creating some indices. In case of MySQL there is also a handy keyword named "EXPLAIN" to show how MySQL tries to fetch the data. Please read the documentation to get more information about that topic.

    Bernhard
    • CommentAuthortom
    • CommentTimeMar 13th 2008
     
    Hi Bernhard,

    thanks for the advice, I didn't know that EXPLAIN statement. :)

    ...but: Are you sure fetching a single database row may take a whole second? The id I'm using in the WHERE clause is the primary key, so there is an index on it. And, doing a similar query via the mysql commandline client takes "0.00 sec", even if the connection is newly created...

    Doesn't anyone else get such long delays with Akelos?

    Regards,

    Tom
    • CommentAuthorbjmg
    • CommentTimeMar 13th 2008
     
    Hi!

    Well then I would assume that akelos has to fill the cache (template cache) in the first run. This could take some time. But I am not sure. I just started to learn akelos.

    Bernhard
    •  
      CommentAuthorbermi
    • CommentTimeMar 13th 2008
     

    Akelos does not cache database column schema on development mode and that makes it slow when loading a model for the first time.

    On production mode (not on console apps) it will cache the schema to improve performance.

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