Highlights of CentOS MySQL operations

Highlights of CentOS MySQL operations How to operate MySQL on CentOS: 1. The problem [root @ rekfan mysql] # service mysql restart occurs.MySQL server PID file cocould not be found! [Failed]Starting MySQL... The server quit without updating PID file

Oracle merge into usage

Oracle merge into usage 1. Use of merge Merge is a very useful feature. It is similar to merge into in DB2 and insert into on duplicate key in Mysql. Merge into is a new feature that appears after Oracle 9i. In simple terms, it can be a function of "

Oracle NULL column and PL./SQL Execution Experiment

Oracle NULL column and PL./SQL Execution Experiment Today, we have some experiments on Oracle NULL values. We will discuss how to insert NULL values. 1. You can insert ''or NULL in PL/SQL, provided that the column is allowed to be empty. 2. You can

MySQL uses binary logs to restore the database

MySQL uses binary logs to restore the database 1. Introduction to binary logs MySQL has different types of logs, in which the binary file records all changes to the database. If the database loses data due to improper operations or other reasons, it

MongoDB cluster in Linux-replica set Environment Construction

MongoDB cluster in Linux-replica set Environment Construction MongoDB replica sets are suitable for scenarios with fewer writes and more reads. You can use message queues for write control to reduce the pressure on highly concurrent writes. The

DB2 memory usage too high Optimization

DB2 memory usage too high Optimization Recently, I was working on the benchmark of DB2 and found that the memory usage of the database was very high. Because the benchmark test was performed, there were not many tables, And I mainly tested one of

DB2 view execution plan

DB2 view execution plan In DB2, it is not convenient to view the SQL Execution Plan for other databases. Several steps are required. Here I organize the steps into shell scripts for ease of use, as shown below: #! /Bin/sh Db2 connect to Db2-tvf $

Oracle problems with number type conversion to_char

Oracle problems with number type conversion to_char Oracle problems with number type conversion to_char Select to_char (0.1) nums from dual; It is observed that if the integer of a decimal number is 0 and the preceding 0 is not displayed after

Use Case of MySQL quick backup tool XtraBackup in production environment

Use Case of MySQL quick backup tool XtraBackup in production environment There are many ways to back up MySQL. The most common method is MySQLdump. Export the database to an SQL file. When restoring, source db. SQL is executed happily. Our friends

Oracle segmented Query

Oracle segmented Query For example, you can use the LAG and LEAD statistical functions to query segments in Oracle on the Internet, the Lag and Lead functions can retrieve the data of the first N rows and the value of the last N rows of the same

Some problems encountered during RedHat + Oracle installation are worth summarizing

Some problems encountered during RedHat + Oracle installation are worth summarizing Yesterday, a RedHat Linux version 5 + Oracle was installed in the middle of the night. Several things were encountered during the installation. The statement is as

ORA-00130: invalid listener address error resolved

ORA-00130: invalid listener address error resolved Log on to the Oracle database. The following message is displayed: Ora11g> sqlplus dcsopen/dcsopen1SQL * Plus: Release 11.2.0.1.0 Production on Mon Jan 5 18:49:31 2015Copyright (c) 1982,200 9,

Oracle modify listening port 1521

Oracle modify listening port 1521 In Oracle, the default listening port number is 1521. Once someone scans this port number, it will know that this server is an Oracle database server. This poses an extremely high security risk, how to modify the

Exploration of MySQL MMM data inconsistency

Exploration of MySQL MMM data inconsistency The slave points to the key log output of the new master. Through the log output, we can roughly understand the execution process of MMM automatic failover or online switching. -- Automatic failover and

Compile and install MySQL in Linux

Compile and install MySQL in Linux Recently I want to develop Hadoop, install MySQL, and test sqoop. Since MySQL is open source code, install it in source code. The following describes my test environment: VMware10 + Ubuntu14.04 Kylin Next, let's

Install MongoDB 2.6.5 in CentOS 6/Linux

Install MongoDB 2.6.5 in CentOS 6/Linux MongoDB is a non-relational database (NoSql) that is very popular in the IT industry. Its flexible data storage method is favored by current IT practitioners. MongoDB implements the object-oriented idea. In

Python production environment MySQL database Incremental backup script

Python production environment MySQL database Incremental backup script A common method for MySQL databases is to use MySQLdump to export SQL for backup, but it is not suitable for databases with large data volumes. The speed and table lock are two

Impact of InnoDB Isolation Mode on MySQL Performance

Impact of InnoDB Isolation Mode on MySQL Performance I have written two articles over the past few months: one is the dangerous debt related to the history of InnoDB transactions, and the other is the truth about the serious performance problems

Oracle restrict connected IP addresses

Oracle restrict connected IP addresses In Oracle, you can control which IP addresses can connect to the database and which IP addresses cannot connect to the database. In 9i and later, setting the allowed IP address and the prohibited IP address is

After the memory usage of apsaradb for Redis reaches the value set by maxmemory, the gamer data cannot be written.

After the memory usage of apsaradb for Redis reaches the value set by maxmemory, the gamer data cannot be written. Let's talk about our company's redis application scenarios. Currently, online games use redis as the front-end cache of MongoDB to

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