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From:Johan De Meersman Date:February 1 2010 9:29am
Subject:Re: extend via table VS extend via database
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If you have performance problems, and no slowlog, maybe it just isn't
enabled in your config ?

Your indexes may not have changed, but the size of your data has. A query
that does a full tablescan will run acceptably on a few thousand records,
but be damn slow on a few million - especially as soon as the size of the
dataset to be scanned exceeds the system's filesystem cache.



Find out what queries are going slow, and use explain to see what you can do
about it.

On Sun, Jan 31, 2010 at 3:46 PM, Cui Shijun <rancpine@stripped> wrote:

>  I had checked slow log & indexes, but no slow log exists, neither
> did the indexes change since the tables were created.
> Besides, The way I deleted old data is drop some unused table. No
> query were performed to those tables when I do that.
> I guess something really "magic" had happened when mysql dropped
> tables in that situation.  :-P
>
> 2010/1/31 Johan De Meersman <vegivamp@stripped>:
> > the first things to look at are usually the slowlog and indexes :-)
> >
> > On 1/30/10, Cui Shijun <rancpine@stripped> wrote:
> >>   Mainly performance issues & maintain cost consideration.
> >>   I've experienced a performance regression a few days ago. The box
> >> running mysql got
> >> a continuous suddenly-high user% cpu, util I delete some old data( 20G
> >> ), which caused
> >>  by several data migrations.
> >>   To avoid the above situation, I decided to split the table, so that
> >> I can move some of them to
> >> other boxes if necessary, to keep the amount of data per mysql in a
> >> suitable range. This is
> >> certainly not a way of solve a problem completely, but might be a way
> >> that works before I figure
> >> out what had happened to mysql.
> >>
> >> 2010/1/29 Johan De Meersman <vegivamp@stripped>:
> >>> On Fri, Jan 29, 2010 at 9:52 AM, Cui Shijun <rancpine@stripped>
> wrote:
> >>>>
> >>>>   I'm using innodb engine. There are more and more rows in my table
> >>>> recently, and
> >>>> I've planned to extend the structure.
> >>>
> >>> Why do you want to split your table ? What problems are you trying to
> >>> solve
> >>> ?
> >>>
> >>>
> >>> --
> >>> Bier met grenadyn
> >>> Is als mosterd by den wyn
> >>> Sy die't drinkt, is eene kwezel
> >>> Hy die't drinkt, is ras een ezel
> >>>
> >>
> >
> >
> > --
> > Bier met grenadyn
> > Is als mosterd by den wyn
> > Sy die't drinkt, is eene kwezel
> > Hy die't drinkt, is ras een ezel
> >
>



-- 
Bier met grenadyn
Is als mosterd by den wyn
Sy die't drinkt, is eene kwezel
Hy die't drinkt, is ras een ezel

Thread
extend via table VS extend via databaseCui Shijun29 Jan
  • Re: extend via table VS extend via databaseJohan De Meersman29 Jan
Re: extend via table VS extend via databaseJohan De Meersman1 Feb