This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
I'd read a primer on database indexes (ask Google). Some systems offer meta-data tables that contain information about the indexes, but aren't actually the index. For example, in some software creating an index would add a line to a table to show the existence of the index. But this is purely representational.