Tag:Primary key

  • MySQL learning notes (14): partition

    Time:2021-3-5

    This article is updated on June 30, 2019, using MySQL 5.7 and operating system deepin 15.4. catalog Partition type Range partition List partition Columns partition Hash partition Key partition Subarea Partition management Partition management of range partition and list partition Partition management of hash partition and key partition Partition type have access toSHOW PLUGINSCheck to […]

  • Creation and use of k-k-row cache module in DCache distributed storage system

    Time:2021-3-2

    By Eaton Introduction|With the development of micro services and cloud, the demand for distributed architecture is becoming more and more common. The traditional SQL structured storage solution has been unable to keep up with the pace, so NoSQL appeared. As a distributed NoSQL caching system based on tars, DCache perfectly supports tars service. In the […]

  • Concept of tcapsusdb knowledge base (table, key, record, index)

    Time:2021-2-27

    As a NoSQL database, the syntax of tcapsusdb is different from that of traditional SQL relational database. This paper will introduce the concept and meaning of the three common terms in tcapsusdb: table, record and index. Terms / concepts First of all, the comparison of tcapsusdb with SQL database and mongodb terms is shown in […]

  • Technical summary – project start [infrastructure manufacturing – Automatic SQL generation + import encapsulation]

    Time:2021-2-27

    Because this project does not use framework, it uses SQLite database. You can imagine how much splicing SQL will be used in the later business, which will be quite troublesome. Once the database changes, a lot of things will have to be changed. So the basic is to encapsulate and generate SQL. Reflection and custom […]

  • MySQL partition

    Time:2021-2-26

    MySQL partition Advantages of partitioning Store more data To optimize the query, only scan one or more necessary partitions. For count () and sum (), only summarize the partition statistics For data that is out of date or does not need to be saved, partitioning is faster Data queries are distributed across multiple disks to […]

  • MySQL partition

    Time:2021-2-26

    MySQL partition Advantages of partitioning Store more data To optimize the query, only scan one or more necessary partitions. For count () and sum (), only summarize the partition statistics For data that is out of date or does not need to be saved, partitioning is faster Data queries are distributed across multiple disks to […]

  • Meet SQL (2)

    Time:2021-2-26

    SQL self study notes constraint 1.0 concept and classification   2.0 non NULL constraint   3.0 unique constraints   4.0 primary key constraints   Automatic growth     5.0 foreign key constraints   Cascade operation     Multi table relation Overview of three situations       Backup and restore of database     multi-table […]

  • MySQL knowledge

    Time:2021-2-25

    What is the difference between hash index and B + tree index? Due to the particularity of hash index structure, the retrieval efficiency is very high, and it can be located at one time.B + tree index needs to be accessed from root node to branch node and then to leaf node for many times. […]

  • All kinds of locks in MySQL

    Time:2021-2-24

    Lock is a mechanism for computer to coordinate multiple processes or threads to access a resource concurrently. Lock ensures the consistency and effectiveness of data concurrent access; lock conflict is also an important factor affecting the performance of database concurrent access. Lock is the concurrency control of MySQL in server layer and storage engine layer.Locking […]

  • After three years of Java, you still can’t optimize MySQL performance

    Time:2021-2-24

    abstract: MySQL performance optimization can make MySQL run faster and save more resources by reasonably arranging resources and adjusting system parameters. MySQL performance optimization includes query speed optimization, update speed optimization, MySQL server optimization and so on. preface MySQL performance optimization can make MySQL run faster and save more resources by reasonably arranging resources and […]

  • The choice of unique index and common index

    Time:2021-2-13

    First, let’s look at the performance differences between the two queries. The data of a field on a unique index can only be unique, while a common index can have duplicate data. Digression: a non primary key index is a query process that returns to the table once more (the only index is also a […]

  • Database notes

    Time:2021-2-11

    Database:   DDl:Create statementCreate, alter, drop, etc   DML:Update data addition, deletion and modification     insert,delete,update   DCL:Define security levels and create users   DQL:Used to query     select,from,where Data type:Int / / integerDouble / / decimalDate / / dateVarchar() / / textTo create a library:Create database ‘database name’View database:   show databases; Delete Library:   drop database;Switch libraries:Use ‘Library name’; To create […]