A few days ago I reported on a problem with savepoints, but all that it appeared to be was an extemporaneous warning message. Well, I just found out that InnoDB can actually lose the savepoints! The overall transaction can still be rolled back successfully, but the savepoints themselves are completely gone. This only occurs after the warning: "Got error 153 from storage engine" happens twice in one transaction (if it only happens once, the savepoints still work) which requires that alternating savepoints be set 6 times. See the full report here: http://bugs.mysql.com/bug.php?id=38187.

One of our developers ran into the strangest error a few days ago, which neither the MySQL manual nor Google searching could find any information on. When he called certain stored procedures in a certain order, he got "Error 153 returned from storage engine." It's been reduced to a very simple test case, and a bug report has been filed. Here's the test case:

DROP TABLE IF EXISTS foo;
CREATE TABLE `foo` (
`a` int(11) NOT NULL auto_increment,
PRIMARY KEY  (`a`)
) ENGINE=InnoDB;

begin;
insert into foo values();
savepoint a1;
insert into foo values();
savepoint a2;
insert into foo values();
savepoint a1;
insert into foo values();
savepoint a2;
show warnings;
rollback;

The very last "savepoint" generates the warning "Got error 153 from storage engine". Any other MySQL'ers use savepoints and …

Last week, I described how to use the MySQL plug-in API to write a minimal 'Hello world!' information schema plug-in. The main purpose of that plug-in is to illustrate the bare essentials of the MySQL information schema plug-in interface.

In this article, I'd like to take that to the next level and demonstrate how to write an information schema plug-in that can access some of the internals of the MySQL server. For this particular purpose, we will focus on a plug-in that reports all the SAVEPOINTs available in the current session. This …