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  MySql index usage

  Teacher Tian, according to the statistics of the questions in the Le Xue Medical examination, there are 50w records, and it takes more than 20 minutes to optimize the sql and establish the index. The response only takes 0.1s SHOW INDEX FROM `exam_question_ record; ALTER TA

  2022-06-01 15:07:26 Views: 274
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  The usage of trim () function

  In oracle, the use of the trim () function is as follows: leading beginning character, trailing ending character, both beginning and ending character, as follows: trim (leading | | trailing | | both 'will

  2022-06-01 15:07:26 Views: 266
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  The difference between oracle execution Plan access and filter

  These two terms in the Predicate Information section indicate when the data source is reduced. Simpl

  2022-06-01 15:07:26 Views: 303
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  Common backup and restore of mysql Notes

  Backup: mysqldump-u user-p pwd-h host dbname [tbname, [tbname...]] > filename.sql-(logical backup)-Q or-quick

  2022-06-01 15:07:25 Views: 237
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  CentOS 6.8system virtual based on vCenter/ESXi platform

  Environment preparation Node 1: CentOS 6.8x86-64CPU:4C memory: 8GB SWAP:8GB hostname: rac01 Business ip:192.168.50.21 Private Network ip:10.98.50.21 Virtual ip:19

  2022-06-01 15:06:55 Views: 298
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  MySQL solves skip-name-resolve very slowly when accessing remotely.

  When the server is tested in the local area network, the access speed of the database is still very fast. However, when the server is put on the external network, the access speed of the database becomes very slow. Later, a solution was found on the Internet, adding [mysqld] skip-name-resolv to my.cnf.

  2022-06-01 15:06:55 Views: 210
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  Optimization after installation of mysql database (remove redundant users and databases)

  1. View the version information of the database: MariaDB [(none)] > select version (); +-+ | version () | +-

  2022-06-01 15:06:55 Views: 287
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  Back up the mysql database with Navicat scheduled tasks

  Need to back up the MySQL database every day, there are many ways to write batch processing or command line backup on the Internet, but here to introduce the method of backup with Navicat tool, stupid operation, very simple. As shown in the figure, together with the system database, there are a total of 12 databases.

  2022-06-01 15:06:49 Views: 299
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  Oracle Study Learning-- Flashback Archive

  Oracle Study Learning-- Flashback ArchiveCREATE FLASHBACK ARCHIVEPurposeUse the CREATE FLASHBACK ARCHIVE st

  2022-06-01 15:06:48 Views: 298
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  Mysql Learning Notes (2-initialization)

  Initialization: (1) set password for root users (in three ways): SET PASSWORD FOR 'username'@'host' = PASSWORD (' your_password'); update mysql

  2022-06-01 15:06:44 Views: 266
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  Elastic ik Chinese word Segmentation Test

  1. Send _ analyze request 2. Return result: {"tokens": [{"token": "Pearl River Estuary", "start_offset": 0, "end_offset": 3, "type": "CN_WORD"

  2022-06-01 15:06:44 Views: 291
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  Introduction to SQL Server data types

  Simply sort out the descriptions of several commonly used SQL server data types for easy reference.

  2022-06-01 15:06:35 Views: 213
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  OpenStack Computing Service Nova [IV]

  OpenStack Computing Service Nova [4] OpenStack Computing Service Nova [4] openstack time: November 28, 2016 Nova introduction: Nova is one of the first two modules of openstack, the other

  2022-06-01 15:06:34 Views: 281
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  Drop user distinction

  Log in to the system administrator account and enter splplus---- > user name: sys as sysdba---- > password: root---- > drop user * in the run window. You must not have any objects under this user in order to use this

  2022-06-01 15:06:09 Views: 290
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  (database) use of SQLite

  Database is widely used in all major operating systems such as Java, Android, IOS, Windows and so on. Although SQLite is a lightweight small engine, it can support databases up to 2TB size, which exists in the form of a single file, as B.

  2022-06-01 15:06:09 Views: 300
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  Python database processing

  #-*-coding:utf-8-*-#! / bin/env python'''#Auth:karl#Function: released version#Date:2017/6/27#Versi

  2022-06-01 15:06:09 Views: 252
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  Oracle Study-AIX6.1 to build Oracle 11gR2 RAC (2)

  Oracle Study-AIX6.1 Construction Oracle 11gR2 RAC (2) I. modify system kernel parameters [root@aix209 app] # chdev-l sys0-a ncargs=256sys0

  2022-06-01 15:06:02 Views: 217
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  [MongoDB Learning Notes 34] Design principles of MongoDB replica set

  There is an important concept in the replica set in MongoDB: most because only one node in the replica set is readable and the other nodes are only readable, while the choice of the primary node is determined by the majority and can continue to be the primary node only when it is supported. (1) the confirmation formula for most of this number: M=in

  2022-06-01 15:06:02 Views: 303
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  A collection of problems encountered in MongoDB slicing

  Question 1: the shard configuration is completely correct, the mongos service can be started normally, and the selection of the shard key is reasonable (previously tested locally), but the data is always concentrated on one shard? In the final resolution process, the following error is prompted after logging in using mongo on a sharding server: root

  2022-06-01 15:06:02 Views: 269
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  Sqlserver uses the ROW_NUMBER () function for data paging

  In Sqlserver database, if the query table contains self-growing Id columns, select Top is generally used to paging the data. In fact, when many data tables are designed, they do not necessarily contain self-growing Id columns, so when the database does not have Id self-increasing columns, it is necessary to

  2022-06-01 15:05:58 Views: 232