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
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
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 ...
1. JSON data at the back end of the request
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 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
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
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, brin index, gin index, merge delay, gin_pending_list_limit, query performance degradation
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
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
Added by robman2100 on Wed, 15 May 2019 09:27:31 +0300
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