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From:Hendrik Woltersdorf Date:April 6 2011 7:49am
Subject:Re: Re: what is ndbinfo.diskpagebuffer.block_instance?
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Thanks for the info. I will do the "group by".

regards

Hendrik Woltersdorf
XCOM AG
Email: Hendrik.Woltersdorf@stripped




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             Jonas Oreland                                                 
             <jonas.oreland@or                                             
             acle.com>                                                  An 
                                        Hendrik Woltersdorf                
             06.04.2011 09:41           <hendrik.woltersdorf@xcom.de>      
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                                        Cluster <cluster@stripped>  
                                                                     Thema 
                                        Re: what is                        
                                        ndbinfo.diskpagebuffer.block_insta 
                                        nce?                               
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




On 04/06/11 09:36, Hendrik Woltersdorf wrote:
>
> Hi,
>
> I query ndbinfo.diskpagebuffer for hitratio as shown in
>
http://dev.mysql.com/doc/mysql-cluster-excerpt/5.1/en/mysql-cluster-ndbinfo-diskpagebuffer.html

>
> In different clusters I get a different number of rows per node-id
> depending on the number of "block_instance"s per node-id.
>
> This column (block_instance) is not really documented for table
> diskpagebuffer. What does it mean here and is this information of any
value
> for me?
>
> regards
>
> Hendrik Woltersdorf
> XCOM AG
> Email: Hendrik.Woltersdorf@stripped

In the multi-threaded data-node,
there are multiple instance of the disk-page-buffer-cache.

the "block_instance" show from which instance the numbers reported are.

> is this information of any value for me

i'd say no...

however, the suggested select to get hit-ratio, on link you provided
should be changed, to perform a group by node_id

e.g

SELECT node_id, 100 * SUM(page_requests_direct_return) / SUM
(page_requests_direct_return + page_requests_wait_io) AS hit_ratio
FROM ndbinfo.diskpagebuffer
GROUP BY node_id

/Jonas
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Thread
what is ndbinfo.diskpagebuffer.block_instance?Hendrik Woltersdorf6 Apr
  • Re: what is ndbinfo.diskpagebuffer.block_instance?Jonas Oreland6 Apr
    • Re: Re: what is ndbinfo.diskpagebuffer.block_instance?Hendrik Woltersdorf6 Apr
      • Re: what is ndbinfo.diskpagebuffer.block_instance?Jonas Oreland6 Apr