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From 王凯 <wjk860...@163.com>
Subject Re:Re: HBase read performance
Date Thu, 13 Nov 2008 03:44:14 GMT
 
 


在2008-11-12,"Michael Stack" stack@duboce.net> 写道:
>王凯 wrote:
>>   
>>> Are you using hbase TRUNK? If so, and if your checkout was recent, 
>>> you'll see benefit/disadvantage of cache.
>>>     
>> hadoop 0.18.1, hbase 0.18.0. I do not use TRUNK , any useful update?
>> what do you mean the disadvantage of cache?
>>   
>Disadvantage is that if you are getting mostly cache-misses, then you 
>will be paying the price of filling the cache but getting no benefit.
>
>There is no data block cache in 0.18.x (by default) so this is not the 
>issue here. Ignore my comments on cache effect from earlier.
>
>>>     
>>>> sorry, i did not explain this clearly. there is 10 columns in the table,
10000 rows in a column ,and the 10Bytes in a row
>>>> the time is 17s, 13.5s, 7.2s
>>>>
>>>>   
>>>>       
>>> 10000 rows in a column? Do you mean 10000 rows in the table and each row 
>>> has an entry in the column? Or do you mean 10 rows in the table and each 
>>> row has 10000 columns?
>>>
>>>     
>> 10000 rows in the table and each row has an entry in the column
>>   
>
>Then the numbers would seem to be way off. Something else must be going 
>on. Is the machine swapping?
>
>
>> DELL PowerEdge 430 , P4 2.8G, 1G Memory. Tooooo poor
>>   
>Is the machine swapping? Are the datanodes running on same machines?
there is no swapping, because we will add swap files in another project.
and the table is only build on one machine!

>St.Ack
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