(Peter Zaitsev) Quite commonly in the applications you would need to use some kind of status field – status of order – new, confirmed, in production, shipped status of job, message etc. People use variety of ways to handle them often without giving enough thought to the choice which can cause proble

This is a continuation of my articles on how to select the desired rows from ranked data. A user recently posed a question in the comments that I thought was particularly intriguing: What is the best way to query 1) Sum of min price of all types? 2) Sum of 2nd highest price of all types?

(Peter Zaitsev) One common question I guess is how much should I see performance improved in case I increase memory say from 16GB to 32GB. The benefit indeed can be very application dependent – if you have working set of say 30GB with uniform data access raising memory from 16GB to 32GB can improve

(Henrik Ingo) While we were mostly excited to become part of Sun, there was at least one drawback too. MySQL had a worldwide policy of “Scandinavian style” 5 week vacations per year (4 Summer, 1 Winter week). Sun doesn’t have such a worldwide policy, so most of us lost some vacation days there. But

(Baron Schwartz) We recently examined a customers system to try to speed up an ETL (Extraction, Transformation and Loading) process for a big data set into a sort of datamart or DW. What we typically do is ask customers to run the process in question, and then examine whats happening. In this case

(Ronald Bradford) I came across this error recently when trying to modify the data type of a column. ERROR 1025 (HY000): Error on rename of ‘./sakila/#sql-1d91_5’ to ‘./sakila/inventory’ (errno: 150)

(Peter Zaitsev) Quite frequently I see customers looking at recovery as on ability to restore data from backup which can be far from being enough to restore the whole system to operating state, especially for complex systems.

(Leo Hsu and Regina Obe) Every once in a while – particularly if you are using inherited tables, you forget to put an important index on one of your tables which bogs down critical queries. Its sometimes convenient to inspect the index catalog to see what tables are missing indexes or what tables ar

(Peter Zaitsev) Have you ever seen the replication stopped with message like this: Last_Error: Could not parse relay log event entry. The possible reasons are: the master’s binary log is corrupted (you can check this by running ‘mysqlbinlog’ on the binary log), the slave’s relay log is corrupted

(Jan Kneschke) Inspired by http://blogs.sun.com/thava/entry/dump_mysql_frm_file_header I jumped into http://forge.mysql.com/wiki/MySQL_Internals_File_Formats and tried to write a decoder for the .frm files. Sadly the internals document is missing all the interesting parts.