Mysql performance for online applications

Hi,

Just asking out of my curiosity. Which of these can hamper performance
of my online applications?

Having multiple small databases open concurrently or huge size of one
single database? What happen for its long term run?

"adzir" <muadzir@yahoo.com> schreef in bericht
news:1176523222.383015.210680@o5g2000hsb.googlegro ups.com...
> Hi,
>
> Just asking out of my curiosity. Which of these can hamper performance
> of my online applications?
>
> Having multiple small databases open concurrently or huge size of one
> single database? What happen for its long term run?
>

That is a tricky one. What is huge?
If you have lots of queries, that will join those small tables, you will pay
a perfomance penalty.
Having one huge database might get you to the limits of the OS.

"Hans H" <jac.habers@hccnet.nl> wrote in message
news:4624e4a4$0$990$9a622dc7@news.kpnplanet.nl...
>
> "adzir" <muadzir@yahoo.com> schreef in bericht
> news:1176523222.383015.210680@o5g2000hsb.googlegro ups.com...
>> Hi,
>>
>> Just asking out of my curiosity. Which of these can hamper performance
>> of my online applications?
>>
>> Having multiple small databases open concurrently or huge size of one
>> single database? What happen for its long term run?
>>
>
> That is a tricky one. What is huge?
> If you have lots of queries, that will join those small tables, you will
> pay
> a perfomance penalty.
> Having one huge database might get you to the limits of the OS.
>

Funny you mentioned this, because in todays lessons we have learned about
this.
It's safer to have multiple small databases because of "update anomalies".
My tech-English is not that good, so I find it difficult to explain. Google
it.

Duz schrieb:
> It's safer to have multiple small databases because of "update anomalies".

Sorry, that's simply wrong (though it may be due to a misunderstanding).

To avoid update anomalies, you normalize a table, which (usually) means
that you split the data into multiple tables.
Having multiple databases doesn't help.

BTW the downside is that you can't JOIN across databases. IOW splitting
into multiple databases is advised if the data should be kept separate.
(Say, a "productive" and a "test" database. Or to enforce safe harbor
constraints, to prevent idle administrators from connecting data that
must remain unconnected.)
I.e. multiple database considerations are about ensuring strategic
properties, while having multiple tables and normalization and avoiding
update anomalies is more "tactical".

Regards,
Jo