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 <[email protected]>: > 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 <[email protected]>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 >> >
