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From Weihua JIANG <weihua.ji...@gmail.com>
Subject Re: How to speedup Hbase query throughput
Date Tue, 26 Apr 2011 05:27:22 GMT
Changing key to user_month may not be useful to me since, for each
query, we only need to get one month report for a user instead of all
the data stored for a user.

Putting multiple month data into a single row may be useful, but not
sure. I will perform some experimentation when I have time.

2011/4/26 Ted Dunning <tdunning@maprtech.com>:
> Change your key to user_month.
>
> That will put all of the records for a user together so you will only need a
> single disk operation to read all of your data.  Also, test the option of
> putting multiple months in a single row.
>
> On Mon, Apr 25, 2011 at 7:59 PM, Weihua JIANG <weihua.jiang@gmail.com>wrote:
>
>> Hi all,
>>
>> We want to implement a bill query system. We have 20M users, the bill
>> for each user per month contains about 10 0.6K-byte records. We want
>> to store user bill for 6 months. Of course, user query focused on the
>> latest month reports. But, the user to be queried doesn't have hot
>> spot.
>>
>> We use CDH3U0 with 6 servers (each with 24G mem and 3 1T disk) for
>> data node and region server (besides the ZK, namenode and hmaster
>> servers). RS heap is 8G and DN is 12G. HFile max size is 1G.  The
>> block cache is 0.4.
>>
>> The row key is month+user_id. Each record is stored as a cell. So, a
>> month report per user is a row in HBase.
>>
>> Currently, to store bill records, we can achieve about 30K record/second.
>>
>> However, the query performance is quite poor. We can only achieve
>> about 600~700 month_report/second. That is, each region server can
>> only serve query for about 100 row/second. Block cache hit ratio is
>> about 20%.
>>
>> Do you have any advice on how to improve the query performance?
>>
>> Below is some metrics info reported by region server:
>> 2011-04-26T10:56:12 hbase.regionserver:
>> RegionServer=regionserver50820, blockCacheCount=40969,
>> blockCacheEvictedCount=216359, blockCacheFree=671152504,
>> blockCacheHitCachingRatio=20, blockCacheHitCount=67936,
>> blockCacheHitRatio=20, blockCacheMissCount=257675,
>> blockCacheSize=2743351688, compactionQueueSize=0,
>> compactionSize_avg_time=0, compactionSize_num_ops=7,
>> compactionTime_avg_time=0, compactionTime_num_ops=7, flushQueueSize=0,
>> flushSize_avg_time=0, flushSize_num_ops=0, flushTime_avg_time=0,
>> flushTime_num_ops=0, fsReadLatency_avg_time=46,
>> fsReadLatency_num_ops=257905, fsSyncLatency_avg_time=0,
>> fsSyncLatency_num_ops=1726, fsWriteLatency_avg_time=0,
>> fsWriteLatency_num_ops=0, memstoreSizeMB=0, regions=169,
>> requests=82.1, storefileIndexSizeMB=188, storefiles=343, stores=169
>> 2011-04-26T10:56:22 hbase.regionserver:
>> RegionServer=regionserver50820, blockCacheCount=42500,
>> blockCacheEvictedCount=216359, blockCacheFree=569659040,
>> blockCacheHitCachingRatio=20, blockCacheHitCount=68418,
>> blockCacheHitRatio=20, blockCacheMissCount=259206,
>> blockCacheSize=2844845152, compactionQueueSize=0,
>> compactionSize_avg_time=0, compactionSize_num_ops=7,
>> compactionTime_avg_time=0, compactionTime_num_ops=7, flushQueueSize=0,
>> flushSize_avg_time=0, flushSize_num_ops=0, flushTime_avg_time=0,
>> flushTime_num_ops=0, fsReadLatency_avg_time=44,
>> fsReadLatency_num_ops=259547, fsSyncLatency_avg_time=0,
>> fsSyncLatency_num_ops=1736, fsWriteLatency_avg_time=0,
>> fsWriteLatency_num_ops=0, memstoreSizeMB=0, regions=169,
>> requests=92.2, storefileIndexSizeMB=188, storefiles=343, stores=169
>> 2011-04-26T10:56:32 hbase.regionserver:
>> RegionServer=regionserver50820, blockCacheCount=39238,
>> blockCacheEvictedCount=221509, blockCacheFree=785944072,
>> blockCacheHitCachingRatio=20, blockCacheHitCount=69043,
>> blockCacheHitRatio=20, blockCacheMissCount=261095,
>> blockCacheSize=2628560120, compactionQueueSize=0,
>> compactionSize_avg_time=0, compactionSize_num_ops=7,
>> compactionTime_avg_time=0, compactionTime_num_ops=7, flushQueueSize=0,
>> flushSize_avg_time=0, flushSize_num_ops=0, flushTime_avg_time=0,
>> flushTime_num_ops=0, fsReadLatency_avg_time=39,
>> fsReadLatency_num_ops=261070, fsSyncLatency_avg_time=0,
>> fsSyncLatency_num_ops=1746, fsWriteLatency_avg_time=0,
>> fsWriteLatency_num_ops=0, memstoreSizeMB=0, regions=169,
>> requests=128.77777, storefileIndexSizeMB=188, storefiles=343,
>> stores=169
>>
>>
>> And we also tried to disable block cache, it seems the performance is
>> even a little bit better. And it we use the configuration 6 DN servers
>> + 3 RS servers, we can get better throughput at about 1000
>> month_report/second.  I am confused. Can any one explain the reason?
>>
>> Thanks
>> Weihua
>>
>

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