mysql issue

Jason Van Patten jason at infogenix.com
Wed Feb 8 16:17:14 MST 2012


On 2/8/2012 4:02 PM, Steve Alligood wrote:
> Why would you run performance critical really large data sets on 
> spindles? If it is performance critical, put your db on SSDs.
>
> This entire discussion has been from a DBA standpoint.  From a 
> SysAdmin standpoint, splitting out your tables into files makes life 
> MUCH better when things go south.  In fact, MyISAM tables are MUCH 
> better when things go south, as they are both easier and faster to 
> repair and get back online.
>
> In fact, if you have a lot of databases (or even more than one) using 
> InnoDB tables and one of them has issues bad enough to where the 
> autorepair doesn't work, you have to dump them all and re-import them 
> all to be sure you got the bad one, as the page dump MySQL so nicely 
> gives you does squat for telling you *which* database or even table is 
> corrupt and is causing all of MySQL do stay offline.  Or you can try 
> hide and seek and randomly try them until MySQL comes back online.  
> That one is fun, too.
>
> I have also found that MyISAM is considerably faster for relatively 
> simple datasets, especially if you are mostly doing inserts and not a 
> lot of selects.  Constraints, checkpoints, row locking, etc, all add 
> overhead.  In fact, if write speed is important, don't even do more 
> indexes that you specifically need.
>
> Basically, if you don't specifically need what InnoDB brings to the 
> party, stick with MyISAM every time and you will have far less 
> problems in a repair situation, simpler management, and faster writes.
>
> -Steve
And then your socket volume spikes and your down. Once you get to the 
point that you are having crashes you should at least look at switching. 
That and/or slap your developers for not optimizing queries. as for 
fixing things when they go south yes myisam is easier, but your risk of 
going down in the first place is higher. Furthermore a competent backup 
system and recovery code can make innodb down time negligible.

Jason
>
>
> On 2/8/12 3:44 PM, Jason Van Patten wrote:
>> On 2/8/2012 3:13 PM, Paul Seamons wrote:
>>> I'd second that, but I'd add a "be sure to add innodb_file_per_table=1
>>> to the my.cnf
>> Be very careful with that entry. It can wreck your seek times once you
>> get really large data sets and can make load balancing moot.
>> Jason
>>> Paul
>>>
>>> On 02/08/2012 12:24 PM, Jason Van Patten wrote:
>>>> On 2/8/2012 11:50 AM, Merrill Oveson wrote:
>>>>> MyISAM
>>>>>
>>>>>
>>>> That might be the reason mysql locked in the first place. You get one
>>>> rouge query that takes too long and every other query hitting  that
>>>> table and all joins has to wait for it. InnoDB is a little slower, but
>>>> it ill only lock rows affected by the query instead of the whole
>>>> table/tables. Unless you are index text columns i would recommend
>>>> switching to Innodb or setting up a watchdog on your process list. 
>>>> Most
>>>> times the watchdog is a good move just so you have time to get innodb
>>>> running (select * statements will all need to get paired down to the
>>>> minimum)
>>>>
>>>> /*
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>>
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>
>
>
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