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HBase - Distributed NoSql Database - Coggle Diagram

- - - - Regions are categorized into
        
        Meta Region > records routing information of User Regions
        
        User region
      - Column Family
        
        Physical storage unit of a region > multiple column families of the same Region have diffrent paths in HDFS
      - Store > reg consists of one or multiple stores > each store corresponds to a column family
        
        StoreFile > the Data flushed to the HDFS is stored as a StoreFile in the HDFS
        
        HFile > defines the storage format of StoreFiles in the file system . HFile is underlying inmplementation of StoreFile
        HFile contains data of multiple columns. and rows
        the KeyValue of HFiles in HBase contains
        
        key / value / TimeStamp / KeyType
        
        MemStore > Store contains one MemSore > Data inserted to a region bt client is cached to the MemStore
      - HLog > prevent data loss when a RegionServer is faulty. Multiple Regions in a Region Server share the same HLog
        data writing success message return to the HLog after the data is successfully written
- - - - Consistency
      - Isolation >> ensures that 2 or more transactions will not be executed in the interleaved manner
      - Atomicity >> requires that each transaction be "all or nothing"
      - Durability >> after transaction is executed successfully modifications made on the database are retained permanently
- - - - needs to request region (bookshelf) number , RowKeys (book number scope) and information about the regionServers (floors) where regions are located
    - - find the information of region and regionserver of tables based on the meta table
        
        Transfer data to specific region according to rowKey
    - - the proces of initiating a writing request is like sending books to a libary by a book supplier. The Book supplier must determine to which building and floor the books should be sent.
  - - - Minor
        
        compactation covering a small range. Min and max numbers of files are specified. Small files at a consecutive time duration are combined
      - Major
        
        compactation covering the HFiles in a column family in a region. During major compactations, deleted data is cleared.
  - - - Get > when a precise key is provided the Get Operation is performed to read a single row of user data.
      - Scan > the Scan operation is to batch scan user data specified key range.