(Eric Bergen) I’ve talked to several people that have questions about how alter table works under the hood. They want to know how it handles locking tables why they can sometimes use a table during alter table and other times they can’t. Also why it’s so slow.

(Xaprb) MySQL Table Checksum 1.1.0 adds many improvements, but the most important is a new way to ensure slaves have the same data as their master. Instead of checksumming the slave and the master, it can now insert the checksum results directly on the master via an INSERT.. SELECT statement. This s

(Reggie Burnett) Connector/Net’s MySqlDataAdapter class has a method named FillSchema. This method is intended to populate the metadata for a given query without actually returning any of the data from the query. The only syntax that MySQL has to help with this is SQL_SELECT_LIMIT which limits the

(Mark Leith) With all the talk lately of the new INFORMATION_SCHEMA plugin API, I thought I’d have a go at making a couple. I’ve now made three different pluggable INFORMATION_SCHEMA tables – one that works from df -k – which will only work on UNIX like systems (other than AIX or HPUX) – and two whi

(Lorenzo Alberton) In our big-brother-esque age, we like to have everything under control. While in real life it may not always be a good thing, we certainly want to know what happens to our data. I’ve seen all sort of solutions to log database changes, many of them in PHP or some other language, b

(Rick F. van der Lans) The GROUP BY clause groups rows on the basis of similarities among them. For example, we could group all the rows in the PLAYERS table on the basis of the place of residence. The result would be one group of players per town. From there, we could query the number of players in

(Sergey Petrunia) Performance-wise, the idea of Prepared Statements is that the server does certain pre-processing on PREPARE command, and then those steps are omitted when the statement is executed. If the statement is executed several times, we get an economy of cost_of_prepare_preprocessing *

(Mark Callaghan) Chip Turner has begun work on a new storage engine that makes it easy to export files as if they were database tables. Why is this good? I have written code to export data from /proc in SHOW STATUS. This makes it possible to track changes in system resource consumption, such as the

(Dathan) I get this question a lot. Why does a slave report that it’s trying to replicate from an impossible position? 9 times out of 10 it’s because the master crashed and when it came back online a new binlog file was made.

(Il Corra) Using MEMORY tables in MySQL is very useful; they are stored in memory and they are usually not so big in order to avoid a huge utilization of RAM. They are very fast.