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From Alan Gates <>
Subject Re: Query performance correlated to increase in delta files?
Date Fri, 20 Nov 2015 22:17:46 GMT
Are you running the compactor as part of your metastore?  It's 
occasionally compacts the delta files in order to reduce read time.  See for 


> Sai Gopalakrishnan <>
> November 19, 2015 at 21:17
> Hello fellow developer,
> Greetings!
> I am using Hive for querying transactional data. I transfer data from 
> RDBMS to Hive using Sqoop and prefer the ORC format for speed and its 
> ACID properties. I found out that Sqoop has no support for reflecting 
> the updated and deleted records in RDBMS and hence I am inserting 
> those modified records into the HDFS and updating/deleting the Hive 
> tables to reflect the changes. Every update/delete in the Hive table 
> results in creation of new delta files. I noticed a considerable drop 
> in speed over a period of time. I realize that lookups tend to take 
> more time with growing files. Is there any way to overcome this issue? 
> INSERT OVERWRITE the table is costly, I deal with about 1TB data, and 
> it keeps growing every day.
> Kindly reply with a suitable solution at the earliest.
> Thanks & Regards,
> Saisubramaniam Gopalakrishnan
> Aspire Systems (India) Pvt. Ltd.
> Aspire Systems
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