Following Restore one table from an ALL database dump and Restore a Single Table From mysqldump, I would like to add my own thoughts and comments on the subject.
I also wish to note performance issues with the two suggested solutions, and offer improvements.
Problem relevance
While the problem is interesting, I just want to note that it [...]
I first read High Performance MySQL, 2nd edition about a year ago, when it first came out. I since re-read a few pages on occasion.
In my previous posts I’ve suggested ways to improve upon the common ranking solution. Very innovative stuff! Or… so I thought.
I happened to browse through the book today, and a section [...]
“Walking a string” is an SQL technique to convert a single value into multiple rows result set. For example, walking the string ‘hello’ results with 5 rows, each of which contains a single character from the text.
I’ll present a brief example of walking a string, and then show how to “unwalk” the string: do the [...]
Sometimes MySQL gets it wrong. It doesn’t use the right index.
It happens that MySQL generates a query plan which is really bad (EXPLAIN says it’s going to explore some 10,000,000 rows), when another plan (soon to show how was generated) says: “Sure, I can do that with 100 rows using a key”.
A true story
A customer [...]