diff -r b0238fc496af -r f6ef18be36e1 mercurial/revlogutils/debug.py
--- a/mercurial/revlogutils/debug.py	Wed Jun 01 01:43:17 2022 +0200
+++ b/mercurial/revlogutils/debug.py	Wed Jun 01 01:34:10 2022 +0200
@@ -109,6 +109,11 @@
     return b"%d" % entry[constants.ENTRY_DATA_UNCOMPRESSED_LENGTH]
 
 
+@debug_column(b"delta-base", size=6, verbose=True)
+def delta_base(index, rev, entry, hexfn):
+    return b"%d" % entry[constants.ENTRY_DELTA_BASE]
+
+
 def debug_index(
     ui,
     repo,