• HDFS / HBase technical report · comprehensive analysis of distributed database design architecture


    Distributed database of Hadoop ecology 1. What is distributed database? In a narrow sense, it is a distributed relational database, mainly referring to the current popular newsql. In a broad sense, the traditional relational database with sub database and sub table, traditional relational database cluster, master-slave architecture of relational database, distributed kV database (e.g. HBase), […]

  • Basic knowledge of affairs


    What is a transaction? Transactions are in the databaseminimumOf processing unitTask set。 It can be one SQL statement or a collection of multiple SQL operations. It can ensure that these task sets are either complete or completeIt’s all done, orNo execution, will not be in an intermediate state. Database is orientedMultithreading and multi-userDesigned to be […]

  • Distributed — basic theory of distributed


    I Cap theorem: Consistency consistency Whether all backups of the same data have the same value at the same time. A common strong consistency implementation is that before you see a consistent result,Write request does not return, read request is blocked or timed out Availability availability When some nodes in the cluster fail, the cluster […]

  • Necessary for back-end programmers: Fundamentals of distributed transactions


    Database transaction Database transaction(Abbreviation: transaction), is a logical unit in the execution of database management system, which is composed of a limited sequence of database operationsEither all or noneOK, it’s ainseparableYour work unit. Several typical characteristics of database transactions: atomicity, consistency, isolation and persistence, which is called acid for short. Atomicity:The transaction is executed as […]

  • [introduction to microservices] use of distributed transaction framework Seata


    Distributed transaction in microservices Let’s imagine a traditional monolithic application. Its business consists of three modules. They use a single local data source. Naturally, local transactions will ensure data consistency. The microservice architecture has changed. The three modules mentioned above are designed as three services on top of three different data sources(Schema: database per service)。 […]

  • NoSQL


    NoSQL NoSQL is a new way to design Internet scale database solutions It is not a product or a technology, but a term that defines a set of database technology. It is not based on the traditional RDBMS principles SQL The concept of RDBMS comes from the white paper entitled “data relationship model for large […]

  • Final consistency implementation scheme of distributed transactions


    preface This article isUnderstanding of distributed transactionsThe following part: the final consistency implementation scheme of distributed transactions. For the e-commerce demand, the business scenario after an order is paid includes the following operations: Change the status of the order to paid Deduct commodity inventory Add points to members Create an issue order and notify the […]

  • InnoDB consistent unlocked reads and consistent locked reads


    Consistent unlocked read 1、 DefinitionConsistent non locking read means that the InnoDB engine reads the data of rows in the database at the current execution time through row multi version control (i.e. multi version concurrency control). If the read row is performing delete or update operation, the read operation will not wait for the release […]

  • Microservice architecture | 11 Distributed transaction


    catalogue preface 1. Basic knowledge 1.1 theoretical model of distributed transaction problem 1.1.1 X / open distributed transaction model (XA protocol) 1.1.2 two stage submission agreement 1.1.3 three stage submission agreement 1.2 two theoretical models of distributed transaction 1.2.1 cap theorem 1.2.2 base theory 1.3 common solutions to distributed transaction problems (transaction mode) 1.3.1 TCC […]

  • Open source distributed file system review


    preface Our yrcloudfile is a distributed file system for the cloud era. Its main features are supporting high-performance data access of massive small files, seamless support for kubernetes platform and data support in hybrid cloud scenarios. When developing yrcloudfile, we will also understand the mainstream distributed file system in the industry, learn its advantages and […]

  • Meituan Interviewer: young man, talk about the principle of volatile keyword?


    preface Before talking about the volatile keyword, let’s talk about the CPU multi-core concurrent cache architecture, then to JMM, that is, the JAVA memory model, and finally to the volatile keyword. JMM (JAVA memory model) Introduction of multi-core concurrent cache architecture In order to solve the mismatch between the speed of CPU and main memory, […]

  • Cache consistency between MySQL and redis


    In high concurrency scenarios, it is obvious that using Mysql to provide data services alone cannot meet the throughput of the system. In the current system architecture, we generally use redis as data cache to avoid too many requests to go to the database, which will affect the system performance. However, in high concurrency scenarios, […]