Mycat configures Mysql read-write separation + forced walk-write node + read-write separation based on master-slave delay

Database read-write separation is an indispensable and important function for large-scale systems or high-volume Internet applications. For MySQL, the standard read-write separation is the master-slave mode. A write node Master is followed by multiple read nodes. The number of read nodes depends on the pressure of the system, usually the confi ...

Added by lucilue2003 on Thu, 16 May 2019 22:21:46 +0300

[Cluster monitoring] Using Prometheus + grafana + node-exporter

Framework principle Introduction to Prometheus Prometheus (Chinese name: Prometheus) is an open source monitoring and alarm system and time series database (TSDB) developed by SoundCloud. Prometheus has been adopted by many companies and organizations since 2012, and the project has a very active developer and user communit ...

Added by trrobnett on Thu, 16 May 2019 17:13:01 +0300

Programming of PC/SC Smart Card Interface under Linux

PC/SC (Personal Computer/Smart Card) specification, PC/SC specification as a standard interface between card reader and card and computer, realizes the interaction between card and card reader of different manufacturers. The source code pcsc-lite running under Linux is http://pcsclite.alioth.debian.org/ There are demo ...

Added by Texan on Thu, 16 May 2019 16:28:44 +0300

Ajax Data Request Server for Integration of Front-End Note Points & Resolving Cross-Domain & Three-Level Linkage & session & Stack

1. JSON data at the back end of the request JSON is an interactive format for front-end and back-end communication. JSON(JavaScript Object Notation, JS Object Markup) is a lightweight data exchange format. JSON is a necessary format for communication between backstage and predecessors of the Internet, replacing the original XML. XML data fo ...

Added by Chappers on Wed, 15 May 2019 22:03:54 +0300

General database role privilege handling in SQL Server

General database role privilege handling in SQL Server   Recently, we have been doing database privilege cleanup with colleagues, mainly by deleting some accounts, removing the larger privileges of some accounts, etc. For example, some have db_owner privileges, we remove the database role db_owner of the accounts and grant the minimum required ...

Added by Karpathos on Wed, 15 May 2019 18:59:55 +0300

Fabrication Process of Imitating 9GAG (V)

I have something to say: After completing the data display function, I want to improve the whole APP. It is found that the background is very chaotic, and there are many points that are not available. For example, the picture should have thumbnails and original pictures, paragraphs, comments and comments should be linked together, paragraphs sh ...

Added by gordo2dope on Wed, 15 May 2019 17:30:51 +0300

Python Reptilian Actual Warfare: Climbing the All-Station Novels List

As you all know, there are always some novel that is refreshing, whether it is fairy-man or fantasy. The first dozen chapters successfully circled a large wave of fans, successfully climbed the soaring list, hot list and other lists, throwing a few chestnuts out: As a developer, it is particularly important to have a lea ...

Added by eabigelow on Wed, 15 May 2019 12:37:31 +0300

PostgreSQL page inspect diagnoses and optimizes the query performance degradation caused by the delay of GIN (inverted) index merging

Label PostgreSQL, brin index, gin index, merge delay, gin_pending_list_limit, query performance degradation background GIN index is an inverted index of PostgreSQL database with multi-value type. A record may involve KEY in multiple GIN indexes. So if index is merged in real time when writing, IO will increase sharply and RT will increase in ...

Added by hatching on Wed, 15 May 2019 09:30:25 +0300

CDH Installation Documentation

1. Installation environment CentOS 6.8 Virtual Machine Three 1G per memory 50G per hard disk 2. Installation packages required CDH5.9.0 Installation Package Files included: Parcel contains files: Files included in rpms: Before you start the installation below, make sure the number of files is correct 3. Installation steps First, ...

Added by robman2100 on Wed, 15 May 2019 09:27:31 +0300

InnoDB Engine B+Tree Index Usage and New Features

We've already talked about it Principle and algorithm of MySQL InnoDB index Here's how to manage and use B+tree indexes and some new features. Management of B+Tree Index The basic indexes we use in the InnoDB engine are B+tree indexes. Create and delete indexes It can be created and deleted in two ways: # Mode 1: alter table, in which case bot ...

Added by ehhwan on Wed, 15 May 2019 05:12:03 +0300