In your development work, there are sometimes you forgot the mysql root password so you cannot make any system-level change to the mysql server. This quick tutorial tells you how to reset mysql root password in CentOS. First, need to stop MySQL:[bash]root# service mysqld stop[/bash] Then, start MySQL in safe […]
Database
28 posts
Normally MySQL replication will stop whenever there is an error running a query on the slave. This happens in order for us to be able to identify the problem and fix it, and keep the data consistent with the mater that has sent the query. You can skip such errors, even if […]
When working with replication on very big table, we may face problem when update table structure (such as adding an index, removing an index, adding a field, etc.). There are few cases (such as changing indexes) running a local sql is better than having it goes with replication, since the […]
There are some case we need to select random records in mysql. The normal way I did see many developers have used is ORDER BY RAND(). But they might not recognize that if the number of records increase, the query is extremely slow due to the fact that it must […]
This article describe an example of using MySQL as a NoSQL in which the application can exceed 750,000 qps on a commodity server. This is originated from http://yoshinorimatsunobu.blogspot.com/2010/10/using-mysql-as-nosql-story-for.html UPDATE: Oracle officially released memcached daemon plugin that talks with InnoDB. I’m glad to see that NoSQL+MySQL has become an official solution. It’s still preview release […]
Recently, due to a unknown problem, mysql replication in our server was stopped. Checking the log, we found the following error 130225 21:17:32 [ERROR] Error in Log_event::read_log_event(): ‘read error’, data_len: 261, event_type: 2 130225 21:17:32 [ERROR] Error reading relay log event: slave SQL thread aborted because of I/O error 130225 […]
When there are many errors when connecting to a mysql server, the following error might appear and the application cannot connect to the db server any more: Host ‘yourhost’ is blocked because of many connection errors; unblock with ‘mysqladmin flush-hosts’ The above error might appear when the application server and […]
Whenever analysts or journalists assemble lists of the top trends for this year, “big data” is almost certain to be on the list. While the catchphrase is fairly new, in one sense, big data isn’t really a new concept. Computers have always worked with large and growing sets of data, […]
1. Quick Comparison While SQL databases are insanely useful tools, their monopoly in the last decades is coming to an end. And it’s just time: I can’t even count the things that were forced into relational databases, but never really fitted them. (That being said, relational databases will always be […]
In a MySQL Replication based system, How to migrate a master database to another server/host? Scenario in short goes: dump out master databases, import data on the new master server and point slave to the new master server. If you follow this simple steps, master migration should proceed without problems. Export databases from […]