Tag:Number of rows

  • Sparse array


    For an array, if most elements are 0 or other same values and there are only a few different values, the array can be converted into a sparse array for storage, so as to reduce the size of the array and realize the function similar to compression. Convert to sparse array Take the conversion of […]

  • Introduction to fast JDBC


    This paper introduces an open source JDBC operation tool class fastjdbc and a JDBC rapid development kit based on springboot frameworkIn fact, it is a secondary encapsulation of the namedjdbctemplate class provided by the spring framework. It provides an API configuration method based on annotation to operate SQL, rather than calling the namedjdbctemplate method to […]

  • My toolbox (I) – git project submission line count script


    At work, I often need to pay attention to a lot of information.Working on git projects, I usually focus on who submitted a certain submission record and what has been changed. However, it’s interesting to think about some hidden data when you jump out of pure development work.One of the most intuitive data is the […]

  • The function of adding rows and storage space in a statistical table every day


    Use the code provided in the article to make a statistical table, the number of new rows per day and the function of new storage space The implementation steps are as follows: 1. Create table Create a table to store the table space usage every day CREATE TABLE [dbo].[t_rpt_table_spaceinfo]( [table_name] [sysname] NOT NULL, [record_date] [date] […]

  • MySQL show status command details


    Show status server status item introduction Status name Scope explicate Aborted_clients Global The number of connections interrupted because the client terminated because the client did not close the connection properly Aborted_connects Global The number of failed connections attempting to connect to the MySQL server Compression Session Only compression protocol is enabled between client and server […]

  • Leetcode-6-zigzag transformation


    1: Title: A given string is arranged in zigzag from top to bottom and from left to right according to the given number of lines. For example, when the input string is “leetcodeishing” and the number of lines is 3, the arrangement is as follows: L C I R E T O E S I […]

  • Online slow query accident caused by MySQL selecting wrong index


    preface Meet you again! Another two weeks passed, and several half written draft articles were added to my cloud notes. Some are prepared to add more content because the quality does not meet expectations, while others are completely inspired and the content is completely wooden. I envy many big guys. I can produce five or […]

  • Solr multi field grouping statistics, combined with springboot, export excel through FTL template


    1、 Project structure 2、 Pom.xmlAdd dependency packages related to springboot, Solr and freemaker in pom.xml file <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-freemarker</artifactId> </dependency> <dependency> <groupId>cn.hutool</groupId> <artifactId>hutool-all</artifactId> <version>5.2.0</version> </dependency> <!– Spring boot projects must introduce web dependencies — > <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!– Solr dependency introduced by spring boot project — > <!– Introducing Solr library to […]

  • An example of head command in Linux system


    headcommandPrint the first 10 lines of each file to standard output. For multiple files, add a header giving the file name before each file. If there is no file, or if the file is-To read the standard input. How to use headcommand useheaddisplay/etc/passwdThe first ten lines are as follows: [[email protected] ~]# head /etc/passwdroot0:0:root:/root:/bin/bashbin1:1:bin:/bin:/sbin/nologindaemon2:2:daemon:/sbin:/sbin/nologinadm3:4:adm:/var/adm:/sbin/nologinlp4:7:lp:/var/spool/lpd:/sbin/nologinsync5:0:sync:/sbin:/bin/syncshutdown6:0:shutdown:/sbin:/sbin/shutdownhalt7:0:halt:/sbin:/sbin/haltmail8:12:mail:/var/spool/mail:/sbin/nologinoperator11:0:operator:/root:/sbin/nologin How to […]

  • Bash skill: shell script that can move Tetris up, down, left and right


    In Linux bash, the previous article introduced the shell script for displaying colored Tetris. Next, we will continue to introduce how to use the K, J, h, l keys to move a single box up, down, left and right. Script execution effect First, paste the specific execution screenshot of the shell script as follows: In […]

  • Performance tuning of gaussdb (DWS): path intervention


    Absrtact: path generation is the main stage of table association mode determination. This paper introduces several factors that affect path generation: cost_ Param, scan mode, join mode, stream mode, and analyze how to intervene in the path generation from the principle. 1、 Cost model selection As the name suggests, cost_ Param is a parameter that […]