some problem of InnoDB performance optimization

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Hi everyone:


I read the presentation about InnodDB performance optimization what
Heikki Tuuri written in april23 2007.
But now I have some sentences don't know how to understanding. Can you help
me?

Overly long queries (transactions
in general) are bad for performance as a lot of unpurged versions accumula=
te.

In this sentence, I don't know the meaning about 'unpureged version
accumulate'


And I don't how to understanding 'open transaction'?


Required for logical level replication to work properly.

What's the meaning about logical level replication?


Can give problems for portable applications if you port from MySQL-4.0 to l=
ater

What's the meaning about this sentence?





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Best regards
Timo Seven
blog: http://zauc.wordpress.com
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UNIX System Admin

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Re: some problem of InnoDB performance optimization

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Hi,

Lets see If I can help.

Overly long queries (transactions
> in general) are bad for performance as a lot of unpurged versions
> accumulate.
>
> In this sentence, I don't know the meaning about 'unpureged version
> accumulate'
>

When rows are updated new versions are created. They are later removed by
purge thread - only then no active transactions may need them. This is why
long open transactions are expensive.



>
>
> And I don't how to understanding 'open transaction'?
>

This is transaction which is started (opened) but not yet ended by commit or
rollback.



>
>
> Required for logical level replication to work properly.
>
> What's the meaning about logical level replication?
>

MySQL has statement level, also caused logical as well as row based
replication. statement level replication requires updates to be
serializable to work.


>
>
> Can give problems for portable applications if you port from MySQL-4.0 to
> later
>
> What's the meaning about this sentence?
>
>
>
This means you can run into the problems if you upgrade from MySQL 4.0 to
later version. Probably is not much relevant any more.



--
Peter Zaitsev, CEO, Percona Inc.
Tel: +1 888 401 3401 ext 501 Skype: peter_zaitsev
24/7 Emergency Line +1 888 401 3401 ext 911

Percona Training Workshops
http://www.percona.com/training/

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Re: some problem of InnoDB performance optimization

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HI Peter:


Thanks for your answer. I have understand your answer. Thank you very
much.


¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª ¡ª¡ª=A1=
ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ ª¡ª¡=AA=
¡ª

Best regards
Timo Seven
blog: http://zauc.wordpress.com
#####Ç뷭ǽä¯ÀÀ£¬»òÕßÖ¸= B6=A8hosts=B5=
=BD74.200.243.252#######
UNIX System Admin


2010/3/23 Peter Zaitsev

> Hi,
>
> Lets see If I can help.
>
> Overly long queries (transactions
>> in general) are bad for performance as a lot of unpurged versions
>> accumulate.
>>
>> In this sentence, I don't know the meaning about 'unpureged version
>> accumulate'
>>
>
> When rows are updated new versions are created. They are later removed by
> purge thread - only then no active transactions may need them. This is wh=
y
> long open transactions are expensive.
>
>
>
>>
>>
>> And I don't how to understanding 'open transaction'?
>>
>
> This is transaction which is started (opened) but not yet ended by commit
> or rollback.
>
>
>
>>
>>
>> Required for logical level replication to work properly.
>>
>> What's the meaning about logical level replication?
>>
>
> MySQL has statement level, also caused logical as well as row based
> replication. statement level replication requires updates to be
> serializable to work.
>
>
>>
>>
>> Can give problems for portable applications if you port from MySQL-4.0 t=
o
>> later
>>
>> What's the meaning about this sentence?
>>
>>
>>
> This means you can run into the problems if you upgrade from MySQL 4.0 to
> later version. Probably is not much relevant any more.
>
>
>
> --
> Peter Zaitsev, CEO, Percona Inc.
> Tel: +1 888 401 3401 ext 501 Skype: peter_zaitsev
> 24/7 Emergency Line +1 888 401 3401 ext 911
>
> Percona Training Workshops
> http://www.percona.com/training/
>

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