Elasticsearch Series - Aggregated Query

outline Aggregated queries from Elasticsearch have the same effect as aggregated queries from databases. We can learn from them by comparing them, such as summing, averaging, maximizing and minimizing. Basic concepts bucket Data grouping. Some data is bucketed by a field whose values are the same and placed in a bucket.It can be understood as t ...

Posted on Fri, 03 Apr 2020 19:34:33 -0400 by likwidmonster

MySQL MySQL dump backup database

mysqldump backup database mysqldump backup database background mysqldump syntax Backup script crontab Import Other backup methods background The database is not very stable in the test environment, and there is a risk of loss The structure of database table changes frequently. There are test data produced ...

Posted on Fri, 03 Apr 2020 19:01:42 -0400 by mtrp

A case of optimizing the algorithm of C ා query database

Recently, when modifying a program, we found that a program algorithm looks simple. However, because of multiple queries to the database, performance problems are caused. This program mainly uses EPPLUS to read Excel data, check whether the data has existed in the database, and if so, return the existing serial number The original code of the c ...

Posted on Fri, 03 Apr 2020 18:02:31 -0400 by daydreamer

MySQL communication protocol connection phase

[TOC] MySQL communication protocol (3) connection phase MySQL connection lifecycle graph TD A[start] --> |Connect|B(ConnectionState) B --> |Certification success|C(CommandState) C --> |Copy command|D(ReplicationMode) B --> |Copy command|D B --> |Error or disconnection|End C --> |Close connection|End D --> |Close connection| ...

Posted on Fri, 03 Apr 2020 17:29:04 -0400 by therainmaker53

MySQL DB User Guide

0. Import MySQL DB import MySQLdb 1. Create mysql connection db = MySQLdb.Connect(host='localhost', port=3306, user='root', passwd='root', db = 'test') Parameters are based on your configuration. Here, take localhost as an example. 2. Get cursor cursor = db.curso ...

Posted on Fri, 03 Apr 2020 16:26:59 -0400 by Dorky

The method of mysql rebuilding table partition and keeping data

This paper introduces the method of rebuilding the table partition and keeping the data in mysql. The partition of mysql can separate the records of a table into several areas for storage. When querying, the records can be searched in the corresponding partition according to the query conditions, instead of the whole ta ...

Posted on Fri, 03 Apr 2020 15:50:30 -0400 by psy

Redis introduction and implementation of lock and count

1, About RedisRedis (Remote Dictionary Server), that is, remote dictionary service, is an open-source log and key value database written in ANSI C language, supporting network, memory based and persistent, and provides API s in multiple languages.Redis supports more value types, including string, list, set, Zset and hash. These data types supp ...

Posted on Fri, 03 Apr 2020 11:42:01 -0400 by ThoughtRiot

Common operations for mongodb

#Backupmongodump.exe -h 127.0.0.1:27017 -d medicine -c jddj -o C:\MongoDB\Server\4.2\backup#Recoverymongorestore.exe -h 127.0.0.1:27017 -d medicine -c jddj C:\MongoDB\Server\4.2\backup\medicine\jddj.bson #Export json, csv data mongoexport.exe -h 127.0.0.1:27017 -d medicine -c jddj -o E:\Crawler Project\json\jddj.json mongoexport.exe -h 127.0.0 ...

Posted on Fri, 03 Apr 2020 01:38:58 -0400 by verlen

15.2 database (2): basic addition, deletion, modification and query of MySQL

@ overview Adding, deleting, modifying and querying are the basic operations of database; Traditionally, CRUD is used to represent add, query, change and delete respectively: create, retrieve, update and delete; The operation of adding, deleting, modifying and querying database is realized by SQL statement; SQL statements in ...

Posted on Fri, 03 Apr 2020 00:50:14 -0400 by xentrix

phpspider generates content collection url on the list page

Need to collect some radio related news, Baidu search, the original idea is to go into Netease, or Sohu or other large news platform for search, keyword crawling It turns out that Netease News doesn't have access to search news, and many of the news that Sohu searches out is difficult to filter videos, which is also a little difficult to do L ...

Posted on Thu, 02 Apr 2020 22:20:04 -0400 by icd_lx