NoSQL introduction practice notes I

1. First time to know NoSql

• Definition
  • The subject conforms to the non relational 、 Distributed 、 Open source and next generation database with horizontal expansion capability
• Database classification
  • TRDB Traditional relational databases
    • Use strong storage mode technology . Refers specifically to database tables 、 That's ok 、 Field creation , All need to be defined in advance , And related attribute constraints
    • use SQL Count standard to define and operate the database
    • Use strong transactions to ensure availability and security
    • It mainly adopts single machine centralized processing （CP） The way
  • NoSql database
    • Using weak storage mode technology
    • There is no SQL Technical standards to define and operate databases
    • Weak transactions are used to ensure data availability and security, or there is no transaction processing mechanism at all
    • It mainly adopts multi machine distributed processing mode
  • NewSql database
    • To achieve NoSql Technology is fast 、 Effective big data processing capability , But also to achieve the traditional relational database SQL、 Advantages of transaction processing
    • The main products PostgreSQL、SequoiaDB（ domestic ） 、SAPHANA 、MariaDB、VoltDB、Clustrix

2. TRDB And NoSql Technical comparison of

• Stand alone instructions contain opcode and Operands Two parts
• Hat theorem （CAP）
  • Uniformity – Meet the function of synchronous data replication
  • Usability – Meet the operation function of updating at any time
  • Partition tolerance – Meet the function of reading valid data at any time
• ACID
  • Atomicity A transaction is an indivisible unit of work , Many operations contained in transactions are either done , Either not
  • Uniformity The transaction must be to move the database from one consistency state to another consistency state . Consistency and atomicity make closely related
  • Isolation, The execution of one transaction cannot be interfered by other transactions . Concurrent transactions cannot interfere with each other
  • persistence Once a transaction is committed , Its changes to the data in the database should be permanent , Subsequent operations or failures should not have any impact on it
• NoSQL characteristic BASE
  • Basic available （BA） Partial failure is allowed , But the rest can continue to work
  • Soft state （S） Allow data status to be temporarily inconsistent , But after error correction, it will finally be consistent
  • Final agreement (E) The final processing result will be consistent
• SQL technical standard
  • Data query language （Select）DQL
  • Data operation language （Insert、Update、Delete） DML
  • Transaction language (Begin Transaction、Commit and Rollback)
  • Data control language （ adopt Grant and Revoke Get permission to ）DCL
  • Data definition language （Create and Drop）DDL
  • Pointer control language （Declare Cursor、Fetch Into and Update Where Current）