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From 王凯 <wjk860...@163.com>
Subject Re:Re: HBase read performance
Date Wed, 12 Nov 2008 04:59:01 GMT
 




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!

>
>> 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

>Thanks,
>St.Ack

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