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From 王凯 <wjk860...@163.com>
Subject Re:Re: HBase read performance
Date Wed, 12 Nov 2008 10:04:19 GMT
 
 


在2008-11-12,"Michael Stack" <stack@duboce.net> 写道:
>王凯 wrote:
>>  
>>
>>
>>
>>
>> 在2008-11-12,"Michael Stack" <stack@duboce.net> 写道:
>>   
>>> 王凯 wrote:
>>>     
>>>> hello, every one. i used to test the performance in PE, but the performance
is not well enough. 
>>>>       
>>> Please say more.  What kind of numbers were you getting?
>>>
>>>     
>>>> especially, the table format is not as what i need. so, i create a table
and write some string in every cell. then, i use the count , the count time is the count_1
time. 
>>>> after all, i count all the tables again, the count time is the count_2 time.
count_2 time is almost half of the count_1 time!
>>>>
>>>> i do not know why this happened, perhaps cache?
>>>>   
>>>>       
>>> Perhaps. If you enable DEBUG and look in the regionserver log, you can 
>>> see log of cache hits and misses.  Try and get general sense of how 
>>> first run compares to second.  Are your reads random or serial?  If 
>>> serial, then yeah, cache is going to help.
>>>     
>> thanks, i am a new comer
>> when the data would be in cache? some times , the count time is never change!
>>   
>
>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?
>
>
>>>> column 	row 	  cell 	write  	count_1  	count_2 
>>>> 10	     10000	   10B 	 17.2        13.5	         7.2
>>>> 10	     10000	   50B 	 17	        13.1	         7.3
>>>> 10	     10000	   200B     19.7	        13.6	         7.6
>>>> 10	   100000	  10B 	128.4	131.5	74.7
>>>> 10	   100000	  50B 	134.6	143.1	66.2
>>>> 10	   100000	  200B      138.1	100.1	77.3
>>>>
>>>>   
>>>>       
>>> What is above saying?  That in column 10, you wrote 1000 items of size 
>>> ten bytes?  The write took 17.2ms, first read 13.5ms and the second 7.2ms?
>>>
>>>     
>>
>> 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
>
>17seconds, 13.5seconds and 7.2seconds are not what we usually see. Tell 
>us more about your hardware setup.

DELL PowerEdge 430 , P4 2.8G, 1G Memory. Tooooo poor!

>Thanks,
>St.Ack

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