diff --git a/README.md b/README.md
index 320f340..3f3b69f 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,8 @@ Using dindexer is pretty straightforward: mount your DVD and scan it. For exampl
     mount /dev/cdrom /media/my_backup
     dindexer --setname "My generic backup 2015-11-13" /media/my_backup
 
+The program will go through every file in the path you specify. Hashing everything in that path could take a bit of time, so please be patient.
+
 You can run dindexer --help to see a list of available switches.
 
 #   Build instructions   #
@@ -37,4 +39,20 @@ You can run dindexer --help to see a list of available switches.
 I never tested dindexer on anything other than Linux. Note that the code assumes paths to be Unix-like. Other than that, there shouldn't be any major problem to porting the code.
 
 ##  Project status  ##
-This project is still being developed. Currently, only the indexer has been implemented. You can search the database manually if you know how to write the SQL queries you will need.
\ No newline at end of file
+This project is at an early stage and is still being developed. Currently, only the indexer has been implemented. You can search the database manually if you know how to write the SQL queries you will need.
+
+#   Useful technical details   #
+##  Queries  ##
+
+### Find duplicates ###
+List all duplicate files belonging to different sets:
+
+    select files.hash, group_id, t.ct from files
+    inner join (
+        select hash, count(*) as ct from files group by hash having count(distinct group_id) > 1
+    ) t
+    on t.hash = files.hash
+    group by files.hash, group_id, t.ct order by files.hash;
+
+#### Set number ###
+In the sets table you can find a disk_number column that is currently not used. This is in case you have numbered discs, so you are free to put any number you like in that column.