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 use filesort for the random…
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 but will be very promising….
NoSQL databases are often compared by various non-functional criteria, such as scalability, performance, and consistency. This aspect of NoSQL is well-studied both in practice and theory because specific non-functional properties are often the main justification for NoSQL usage and fundamental results on distributed systems like the CAP theorem apply well to NoSQL systems. At the same time, NoSQL…
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 21:17:32 [ERROR] Slave SQL: Relay…
APC stands for “Alternative PHP Cache”. APC is a free, open, and robust framework for caching and optimizing PHP intermediate code. This article shows common problems when installing APC and how to fix them. Installing is as simple as [root@search ~]# pecl install apc [root@search ~]# echo “extension=apc.so” > /etc/php.d/apc.ini pcre.h: No such file or…
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 db server are located in…
In 2010, when the world became enchanted by the capabilities of cloud systems and new databases designed to serve them, a group of researchers from Yahoo decided to look intoNoSQL. They developed the YCSB framework to assess the performance of new tools and find the best cases for their use. The results were published in…
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, and we’ve had databases and…
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 the best for the stuff…
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 the master server Stop replication…