Writing a MySQL Plugin

I am currently looking into writing a plugin for mysql in C. I have been reading and studying MySQL 5.1 Plugin Development (http://www.amazon.com/MySQL-Plugin-Development-Sergei-Golubchik/dp/1849510601) which has been helping me out a lot. However I can't seem to find any examples that execute queries. I tried Googling for one but couldn't find any relevant examples. My goal for the time 开发者_高级运维being is to write just a simple plugin that after some data is entered into a table will just perform some basic select queries. If anyone would be willing to share a link to such an example or provide one, it would be most appreciated.

I haven't used Mysql with C before, however you might want to take a look at these links:

1. http://dev.mysql.com/doc/refman/5.1/en/c-api-function-overview.html
2. http://www.mysql.com/downloads/connector/c/

If you know MySql I think those links would be a good starting point at least.

As someone who's written a storage engine plugin, I've found that executing a query from within a MySQL plugin is incredibly difficult. MySQL isn't re-entrant, due to locking within the MySQL process. You could use the MySQL client api (as suggested by chris) to connect to the same server. But it is 99% likely you will simply deadlock the whole server.

I do not know if this might help, but I have created a small mysql plugin written in C. The plugin basically sets up a function which when triggered from mysql will send information about a remove, insert or update query to a running node socket server.

You can find the repository here:

https://github.com/Cyclonecode/mysql-notification

It sounds to me like it's not a good idea to try to execute queries within a storange engine, because this introduces re-entrancy that the server doesn't handle.

However, it is possible that you could do it from a daemon thread, as the event scheduler already does. Likewise, Handlersocket does something similar (but uses the handler API rather than executing queries).

In any case, it all sounds a bit fishy. If you are just learning, try writing a few UDFs (they're easy).