MySQL Exotic Storage Engines

“MySQL has an interesting architecture that sets it apart from
some other enterprise database systems. It allows you to plug in
different modules to handle storage. What that means to end users
is that it is quite flexible, offering an interesting array of
different storage engines with different features, strengths, and
tradeoffs.

“In Survey of MySQL Storage Engines, we discussed some of the
more common storage engines, MyISAM the default, InnoDB, Archive,
Merge, Memory, CSV and NDB. This time we’ll cover some of the
newest and more exotic storage engines, and even some that are
still in development.

“Blackhole

“This storage engine acts like Unix’s tried and true /dev/null.
At first glance, /dev/null seems kind of useless; why would I need
that, you might think. However, it turns out to be quite useful,
and can be used for instance by scripts to suppress the output of
stdout or stderr. It can also be used to overwrite a file with
nothing, i.e. delete contents but keep the file in place. If you
have a program that requires a file to store information that for
some reason you don’t want stored, for instance your friendly
neighborhood browser, you can use /dev/null as a creative trick to
send such output into a virtual blackhole.

“In this way, applications that store their information in
tables can use the blackhole storage engine if they want that
information to disappear automatically. Create a view for the
application to use, and then point the view at a real table for
storage, or a blackhole table when you don’t want the information
to be persistent. Privacy related applications come to mind.”

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