hbase a basic knowledge

What is 1. hbase

Comic learn hbase ---- most straightforward Hbase architecture principles to resolve 
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The concept of 1.1 hbase

• hbase based on Google's BigTable paper is to establish the hdfs on providing high reliability , high performance , column-store , scalable , real-time reading and writing distributed database system. In need real-time read and write random accessing very large scale data sets, you can use hbase.

1.2 hbase features

• Mass Storage
  

  • You can store large quantities of data

• Columnar storage
  

  • Hbase data table is stored based on the column group, the group is divided in the column direction of the column.

• Easy expansion
  

  • Underlying rely HDFS, when insufficient disk space, only need to dynamically increase datanode service node (machine) on it

  • You can increase the storage capacity by adding server clusters

• High concurrency
  

  • Support high concurrent read and write requests

• Thin
  

  • Sparse mainly for flexibility Hbase column, the column family, you can specify any number of columns, column data in the case of empty, will not take up storage space.

• Multiple versions of data
  

  • Hbase data table can have multiple versions values, default is distinguished according to the version number, the version number is the time stamp data inserted

• A single data type
  

  • All the data is in hbase byte array stores

2, hbase overall architecture

• 1、Client
  

  • Client

    • Client contains the interface to access Hbase

    • Further Client also maintains a cache to speed access to the corresponding Hbase, such as the cache .META. Metadata information

• 2、Zookeeper
  

  • zookeeper cluster

    • effect

      • To achieve a high availability HMaster

      • Hbase saved metadata information is hbase table entry address all

      • HMaster realization of monitoring and HRegionServer

• 3、HMaster
  

  • Boss hbase cluster

    • effect

      • For the allocation Region HRegionServer

      • Maintenance of the entire cluster load balancing

      • Maintain metadata cluster information

      • It found that the failure of the Region, and the failure of Region assign to a normal HRegionServer

• 4、HRegionServer
  

  • hbase cluster brother

    • Region responsible for managing

    • Receiving client requests to read and write data

    • Slicing during operation becomes large region

• 5、Region
  

• Minimum unit stored in the distributed cluster hbase

3, hbase table data model

• rowkey
  

  • Line key

    • Primary keys of the table, the table records lexicographically sorted by the rowkey

• Column Family
  

  • Column family

    • Hbase each column in the table, are vested with a column family. Column group is part of a table schema (rather than columns), the table must be defined before use.

• Timestamp
  

  • Timestamp

    • Each time stamp data corresponding to the operation, can be seen as a version number version number data

• Column
  

  • Row

    • The following specific column column family

    • It belongs to a ColumnFamily, similar to the concrete column we created among mysql

• cell
  

  • Cell

    • Key Row from the {, column (= <Family> + <label> ), Version} uniquely determined unit

    • Data is not the type of cell, the entire memory array in bytes