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Restore single MySQL table from a full mysqldump backup file
If you need to restore a single table from a full MySQL backup, you may find yourself wondering “how do I do that?”. There are a few steps required, I outline them here for you to restore the contents of just one table back into the database from the mysqldump using Bash.
Continue readingHow to optimize your WordPress hosting – 9+ practical tips
Isn’t it true that, when you (start to) develop WordPress websites for clients, and you host them yourself, you find yourself in a situation where you need to know a lot about “stuff” other than WordPress development? In this optimizing WordPress hosting post, I provide 9+ practical tips for you, to improve WordPress hosting performance. Especially useful if you plan to develop and host WordPress […]
Continue readingMySQL InnoDB performance improvement: InnoDB buffer pool instances – Updated!
Are you running into MySQL load problems? Learn how how I tuned my MySQL servers for a heavy InnoDB workload, by configuring innodb_buffer_pool_instances. Dividing the InnoDB buffer pool into multiple instances improves Disk I/O. By doing so, you run your database and website more efficiently and faster. Here is a little help for you.
Continue readingMySQL DoS in the Procedure Analyse Function – CVE-2015-4870
Sri Lankan Security researcher Osanda Malith discovered a DoS -or crash- vulnerability in MySQL’s Procedure Analyse Function. The vulnerability crashes MySQL versions up to 5.5.45.
Continue readingOptimize WordPress MySQL tables through Cron, behind the scenes
To regularly optimize my WordPress database tables, I created a small plugin that utilizes the WordPress Cron feature. This comes in handy to perform database optimization for WordPress on a regular basis, without forgetting about it. Just activate and enjoy. And here is the plugin code …
Continue readingVevida Optimizer WordPress plugin
Installing WordPress is one thing, keeping it up to date is something else. Each week brings new bugs or potential attack scenarios that will make a WordPress website vulnerable to hacks. Enabling automatic updates for all or at least most parts of WordPress solves a large number of problems with irregularly maintained WordPress websites.
Continue readingPHP, MySQL and IPv6: still slow
Years ago, I noticed that PHP connections to MySQL were significantly slower over IPV6 (where a hostname has an IPv6 address or AAAA record), when no MySQL service is listening on that address. The connection is refused, and PHP has to fallback to IPv4. The fallback takes a significant amount of time. Too much time if you’d asked me. Unfortunately this fallback to IPv4 is […]
Continue readingConvert PHP ext/mysql to MySQLi
Convert ext/mysql to MySQLi how-to. This post will show you how to convert your old PHP mysql extension functions to PHP MySQLi extension. Migrating away from ext/mysql to MySQLi – or PHP Data Object (PDO) – is important, because the ext/mysql functions are deprecated as of PHP 5.5.0. If you do not update your PHP code, your website will fail soon!
Continue readingHow to restore a deleted Open-Xchange context?
How-to restore, or recover, an accidentally deleted OX context. If you’ve accidentally deleted an Open-Xchange context (contextid), then that is bad… Here is how to recover a deleted OX context and filestore… Assuming you make Open-Xchange backups of course.
Continue readingHow to disable WordPress comments
The WordPress comment system can be a bless for your blog, because of the user interaction. However, when the WordPress comment option is abused by spammers, it becomes a real pain in the “@ss”. With tens- or hundreds of thousands spam reactions, disabling WordPress comments – and removing – is the only way to go. Here is how to disable WordPress comments in both the […]
Continue readingHow to string replace on all WordPress posts in MySQL
Learn how to replace content in your MySQL database in bulk with MySQL REPLACE. Sometimes it’s useful to know how to bulk edit content in your WordPress MySQL database, using MySQL’s REPLACE() function. Here is how to string replace content in WordPress wp_posts table to bulk edit WordPress posts through MySQL.
Continue readingMySQL sleep() attacks
MySQL sleep() command injection attacks: how not validating your PHP user input can lead to Denial of Service (DoS) attacks against websites and back-end database servers. Simply by putting “AND sleep(3)” in the address bar… Happy SQL injection!
Continue readingMySQL database optimization with indices
Why MySQL indices are so important? At Vevida, we like to help our customers as much as possible. Even with optimizing a MySQL database when they don’t ask for it, or when a customer doesn’t know performance can be improved. For example by adding an index because we spotted a slow query in our slow-query log.
Continue readingConvert MySQL MyISAM tables to InnoDB
Convert MyISAM tables to InnoDB. In the earlier days of MySQL, the default storage engine for your database was MyISAM. This is also why you still encounter a lot of examples with engine=MyISAM online. Nowadays, the default storage engine is InnoDB, and MyISAM is no longer actively developed. Therefore, all MySQL performance optimizations are for InnoDB, and it’s recommended to switch to this as your […]
Continue readingHow to flush MySQL query cache from time to time
How to flush MySQL query_cache to prevent fragmentation of free query cache memory space? Here is a how to for unattended and automatically clearing MySQL’s query cache using a Linux cronjob. And I’ll show you how to on the mysql shell.
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