java - how to control the number of mappers per region server for reading a HBase table -


i have hbase table(written through apache phoenix) , needs read , write flat text file. current bottleneck have 32 salt buckets hbase(phoenix) table opens 32 mappers read. , when data grows on 100 billion becomes time consuming. can point me how control number of mappers per region server reading hbase table? have seen program explains in below url , "https://gist.github.com/bbeaudreault/9788499" not have driver program explains fully. can help?

in observation, number of regions of table = number of mappers opened framework .

so reduce number of regions in turn reduce number of mappers.

how can done :

1) pre-split hbase table while creating ex 0-9 .

2) load data in these regions generating row prefix between 0-9.*

below various ways splitting :

enter image description here

also, have look @ apache-hbase-region-splitting-and-merging

moreover, setting number of mappers not guarantee open many, driven input splits

you can change number of mappers using setnummaptasks or conf.set('mapred.map.tasks','numberofmappersyouwanttoset') (but suggestion configuration ).

about link provided you, don't know how works can check author.


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