diff --git a/zack/objects-per-archive-copy.sql b/zack/objects-per-archive-copy.sql
new file mode 100644
index 0000000..80615e6
--- /dev/null
+++ b/zack/objects-per-archive-copy.sql
@@ -0,0 +1,9 @@
+-- compute the number of objects available in each archive copy, according to
+-- the content_archive table
+--
+-- DB: softwareheritage-archiver
+
+select copies.key as archive, count(content_id)
+from content_archive, jsonb_each(copies) as copies
+where copies.value->>'status' = 'present'
+group by copies.key;