glocate -- ZFS-diff-friendly locate-like utility
-glocate is copylefted free software: see the file COPYING for copying
-conditions.
+This utility is intended to keep the database of filesystem hierarchy
+and quickly display some part of it. Like ordinary *locate utilities.
+But unlike others, it is able to eat zfs-diff's output and apply the
+changes to existing database.
+
+Why I wrote it? I have got ~18M files ZFS data storage, where even
+"find /storage" takes considerable amount of time, up to an hour.
+So I have to use separate indexed database and search against it.
+locate family of utilities does exactly that. But none of them are
+able to detect a few seldom made changes to the dataset, without
+traversing through the whole dataset anyway, taking much IO.
+
+Fortunately ZFS design with Merkle trees is able to show us the
+difference quickly and without notable IO. "zfs diff" command's
+output is very machine friendly. So locate-like utility has to be able
+to update its database with zfs-diff's output.
+
+Why this utility is so relatively complicated? Initially it kept all
+database in memory, but that took 2-3 GiBs of memory, that is huge
+amount. Moreover it fully loads it to perform any basic searches. So
+current implementation uses temporary files and heavy use of data
+streaming. Database in my case takes less than 128MiB of data. And
+searching takes only several seconds on my machine.
+
+It is free software: see the file COPYING for copying conditions.