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From:Johan Andersson Date:June 4 2010 9:42am
Subject:Re: uneven data distribution
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Hi,

can you send the output from:

ndb_desc -p -d <databasename> <tablename>
on some of the larger tables to verify the distribution?

In general , you can get this discrepancy in datamemory usage if you have
1) deleted a lot of records containg VARCHAR/VARBINARY (var sized attrs) 
and the deletion did not free up pages completely so they wasnt returned
2) restarted one data node, this data node will then "compact" the 
var-sized area, and then you will have less DataMemory usage on the 
restarted node.

Look at
http://johanandersson.blogspot.com/2009/03/memory-deallocationdefragmentation-and.html
http://johanandersson.blogspot.com/2009/08/optimize-table-on-cluster-revisited.html

But the problem you describe, that the restarted node use _more_ 
memory,that  i haven't seen before.

BR
johan

Hendrik Woltersdorf wrote:
> Hi,
>
> in one of our clusters we have a very uneven data distribution:
>
> ndb_mgm> all report MemoryUsage
> ndb_mgm> Node 10: Data usage is 5%(17307 32K pages of total 327680)
> Node 10: Index usage is 4%(6481 8K pages of total 131104)
> Node 11: Data usage is 19%(62941 32K pages of total 327680)
> Node 11: Index usage is 4%(6398 8K pages of total 131104)
>
> I did a node restart one node 11, but that did not change anything.
> We are using version mysql-5.1.41 ndb-7.0.13.
>
> Is this uneven distribution normal?
> Can I do something to distribute the data evenly?
>
>
> regards
>
> Hendrik Woltersdorf
> XCOM AG
>
>
>
>
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Thread
uneven data distributionHendrik Woltersdorf4 Jun
  • Re: uneven data distributionJohan Andersson4 Jun
    • Antwort: Re: uneven data distributionHendrik Woltersdorf4 Jun
Antwort: Re: uneven data distributionHendrik Woltersdorf4 Jun
  • Antwort: Re: uneven data distributionHendrik Woltersdorf4 Jun