Hfile : File System for hbaseMemstore: In memory store for hbaseWrite Ahead Log (WAL) is that HLog edits will be written immediately
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WHAT IS IT?It is the Hadoop database, HBASE Sclable Reader Writer Distributed BigDatastore Column Oriented HDFS
FEATURES OF HBASEScalable.Automatic failoverConsistent reads and writes.Sharding of tablesFailover supportClasses for backing hadoop mapreduce jobsJava API for client accessThrift gateway and a REST-ful WebShell support
WHAT IT IS NOTNo sqlNo relationNo joinsNot a replacement of RDBMS
INTRODUCTIONNoSQL HBase is a type of "NoSQL" database. "NoSQL" is a general term meaning that the database isnt an RDBMS which supports SQL as its primary access language.When we should think of using it HBase isnt suitable for every problem. We should have lot of data, if data is less RDBMS is better.Difference Between HDFS and Hbase HDFS is a distributed file system that is well suited for the storage of large files. Its documentation states that it is not, however, a general purpose file system, and does not provide fast individual record lookups in files. HBase, on the other hand, is built on top of HDFS and provides fast record lookups (and updates) for large tables.
THINK ON THISFacebook, for example, is adding more than 15 TB, and processing dailyGoogle addint Peta Bytes of data and processing.Companies stroing Logs, temperature details, and many other prospectives to store and process, which come in peta byte for which conventional technologies will days to read the data forget about processing it.
WHAT IS COLUMNS ORIENTED MEANSGrouped by columns,The reason to store values on a per-column basis instead is based on the assumptionthat, for specific queries, not all of the values are needed.Reduced I/O
HMASTERMaster server is responsible for monitoring all RegionServer instances in the cluster, and is the interface for all metadata changes, it runs on the server which hosts namenode.Master controls critical functions such as RegionServer failover and completing region splits. So while the cluster can still run for a time without the Master, the Master should be restarted as soon as possible.
REGIONSERVERSIt is responsible for serving and managing regions, its like a data node for HBase.These can be thought of Datanode for Hadoop cluster. It serve the client request for the data.It handle the actual data storage and request.It consists of Regions or in better words tables.RegionServers are usually configured to run on servers of HDFS DataNode. Running RegionServer on the DataNode server has the advantage of data locality too
ZOOKEEPERZookeeper is an open source software providing a highly reliable, distributed coordination serviceEntry point for an HBase systemIt includes tracking of region servers, where the root region is hosted