diff --git a/README.md b/README.md
index 9fb8845..35b213d 100644
--- a/README.md
+++ b/README.md
@@ -89,5 +89,18 @@ SELECT shops.title, items.name, shop_items.price, items.item_id,
 This returns an estimate in MiB of the total storage occupied by the saved JSON data
 
 ```
-SELECT SUM(LENGTH(source))/1024/1024 FROM source_store
+SELECT ROUND(CAST(SUM(pgsize) AS REAL)/(1024.0*1024.0), 2) FROM dbstat WHERE name='source_store'
+```
+
+### Deleting JSON logs ###
+
+You can delete the stored JSON whenever you want. It is adviced that you also set all `source_id` references to 0 in order to avoid wrong references to the new JSON logs getting stored in the future:
+
+```
+UPDATE items SET source_id=0;
+UPDATE fame_list SET source_id=0;
+UPDATE icons SET source_id=0;
+UPDATE shop_snapshots SET source_id=0;
+DROP TABLE IF EXISTS source_store;
+VACUUM;
 ```