The Unexpected Find That Freed 20GB of Unused Index Space

Every few months we get an alert from our database monitoring to warn us that we are about to run out of space. Usually we just provision more storage and forget about it, but this time we were under quarantine, and the system in question was under less load than usual. We thought this is a good opportunity to do some cleanups that would otherwise be much more challenging.

To start from the end, we ended up freeing more than 70GB of un-optimized and un-utilized space without dropping a single index or deleting any data!

Using conventional technics such as rebuilding indexes and tables we cleared up a lot of space, but then one surprising find helped us clear an additional ~20GB of unused indexed values!

This is what the free storage chart of one of our databases looked like in the process:

Want to know how we did it?
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Originally published at https://hakibenita.com on February 1, 2021.