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Search Results for: mysql select always sort by primary key

Optimizer hints in MySQL 5.7.7 – The missed manual

In version MySQL 5.7.7 Oracle presented a new promising feature: optimizer hints. However it did not publish any documentation about the hints. The only note which I found in the user manual about the hints …


Generated (Virtual) Columns in MySQL 5.7 (labs)

About 2 weeks ago Oracle published the MySQL 5.7.7-labs-json version which includes a very interesting feature called “Generated columns” (also know as Virtual or Computed columns). MariaDB has a similar feature as well: Virtual (Computed) Columns. The …


MySQL server memory usage troubleshooting tips

There are many blog posts already written on topics related to “MySQL server memory usage,” but nevertheless there are some who still get confused when troubleshooting issues associated with memory usage for MySQL. As a …


[ERROR] mysqld: Sort aborted: Server shutdown in progress

Recently, one of our support customers faced this: “[ERROR] mysqld: Sort aborted: Server shutdown in progress.” At first it would appear this occurred because of a mysql restart (i.e. the MySQL server restarted and the …


InnoDB Full-text Search in MySQL 5.6: Part 3, Performance

This is part 3 of a 3 part series covering the new InnoDB full-text search features in MySQL 5.6. To catch up on the previous parts, see part 1 or part 2 Some of you …


Impact of memory allocators on MySQL performance

MySQL server intensively uses dynamic memory allocation so a good choice of memory allocator is quite important for the proper utilization of CPU/RAM resources. Efficient memory allocator should help to improve scalability, increase throughput and …


When the subselect runs faster

A few weeks ago, we had a query optimization request from one of our customer. The query was very simple like:

This column in the table is looks like this:

The table have …


MySQL-Memcached or NOSQL Tokyo Tyrant – part 1

All to often people force themselves into using a database like MySQL with no thought into whether if its the best solution to there problem. Why?  Because their other applications use it, so why not …


MySQL Optimizer and Innodb Primary Key

Innodb primary key is special in many senses and I was always wondering how well MySQL is integrated with Innodb to take advantage of these special features. Lets see which things work and which things …


MySQL EXPLAIN limits and errors.

Running EXPLAIN for problematic queries is very powerful tool for MySQL Performance optimization. If you’ve been using this tool a lot you probably noticed it is not always provide adequate information. Here is list of …