Joining to different databases table
SELECT <…> FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
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TOP command in Linux
top provides an ongoing look at processor activity in real time. It displays a listing of the most CPU-intensive tasks on the system, and can provide an interactive interface for manipulating processes. It can sort the tasks by CPU usage, memory usage and runtime. can be better configured than the standard top from the procps suite. … Read more
How to I disable echo cancellation module without removing the hardware?
You’ll need to: Stop Asterisk Stop DAHDI Unload the driver for your card from the Linux kernel Load the driver for your card with the module parameter “vpmsupport=0”. You can stop Asterisk with the command: asterisk -rx “core stop gracefully” You can stop DAHDI with the command: /etc/init.d/dahdi stop In order to find the kernel … Read more
find the number of CPU cores on Linux
Multi-core CPU processors are common nowadays, including dual-core processors (e.g., Intel Core Duo), quad-core processors (e.g., Intel Core i5), and hexa-core processors (e.g., AMD Phenom II X6). Also, many server-grade physical machines are equipped with more than one CPU processor. To find the number of physical CPUs: $ cat /proc/cpuinfo | grep “^physical id” | … Read more
MYSQL Partitioning : What is and HOW To ?
The idea behind partitioning isn’t to use multiple servers but to use multiple tables instead of one table. You can divide a table into many tables so that you can have old data in one sub table and new data in another table. Then the database can optimize queries where you ask for new data … Read more
What is the best way to reduce the size of ibdata in mysql?
The busiest file in the InnoDB infrastructure is /var/lib/mysql/ibdata1 This file normally houses many classes of information (when innodb_file_per_table is 0) Table Data Table Indexes MVCC (Multiversioning Concurrency Control) Data Rollbacks Segments Undo Tablespace Table Metadata Many people create multiple ibdata files hoping for better diskspace management and performance. It does not help. Unfortunately, OPTIMIZE TABLE against … Read more
Set Up MySQL Master-Master Replication
Here we will help you to set up Master-Master replication between MySQL servers. In this setup if any changes made on either server will update on an other one. Setup Details: Master-1: 10.0.10.12 Master-2: 10.0.10.18 Database: empmaster Step 1. Set Up MySQL Master-1 Server Edit MySQL configuration file and add the following lines under [mysqld] section. Restart … Read more
remove duplicate mysql table
ALTER IGNORE TABLE `cdr` ADD UNIQUE(`uniqueid`)