mysql issue

Jason Van Patten jason at infogenix.com
Wed Feb 8 16:49:07 MST 2012


On 2/8/2012 4:38 PM, Daniel Fussell wrote:
> On 02/08/2012 03:31 PM, Jason Van Patten wrote:
>>> To some degree, that's a myth.  It may or may not be slower, depending
>>> on the workload.  I think in general it's faster these days, and scales
>>> better.
>>>
>>> Steve
>> This is true if the DB is properly designed, however most of the
>> conversions i've ran from myisam to innodb dramatically and harshly
>> affect performance until things get fixed. The main reasons are "Select
>> *" statements in the code, lack of constraints and views, and probably
>> the biggest cause is allowing null in the column definition and then
>> trying to run a search on the column.  Most db architects i've worked
>> with make these mistakes at least once on mysql. Half of them don't
>> learn and just rely on myisam and a watchdog, So generally i would say
>> myisam is faster for your novice db admin, but i would agree that if you
>> know how to do constraints and views properly you will leave myisam in
>> the dust once you hit the 200k+ record range.
>>
> I understood the performance was backward to that.  MyISAM is great for
> heavy read loads, but is terrible for multiple concurrent write loads
> due to the need to lock the whole table.  InnoDB might be slower on
> selects, but it's faster for multiple concurrent read/write loads.
>
> For example, years ago I setup a central global spambayes database with
> 400k tokens, each record is perhaps 4 fields long, none of them NULL
> (though I admit, I didn't know NULL fields created performance problems;
> I was only aware of the potential for casting surprises.)
>
> Running the spambayes db on MyISAM with 5 mail servers using it was
> painfully slow, spamassassin was constantly spinning, and my queues
> quickly backed up.  I converted the table to InnoDB and all my queues
> suddenly cleared.  Since then, I've had to increase the number of tokens
> stored to 1M, and it still flies.  I'm also keeping an AWL
> (auto-whitelist) table that had the same problem after about 300k
> records or so.  I switched that to InnoDB as well, and it's now well
> over 1M records, and still going strong.
>
> So if you have a heavy/mostly read load, use MyISAM.
>
> If it's a mixed read/write load, or you need foreign keys, transactions,
> etc, use InnoDB.
>
> I've never used InnoDB with files per table option, so I can't comment
> on that.  I will say that my innodb file is roughly twice the size of
> the tables it contains.
>
> Grazie,
> ;-Daniel Fussell
Well the difference is that when working with smaller datasets on poorly 
designed dbs myisam is faster. But like i said once you hit 200K+ 
records innodb will beat myisam query for query. Optimize it for innodb 
and you will see the innodb goodness flow.
Jason
>
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