Enable autovacuum for existing compressed chunks

In old TSDB versions, we disabled autovacuum for compressed chunks to
keep the statistics. However, this restriction was removed in timescale#5118, but
no migration was performed to enable autovacuum for existing chunks.

sql/updates/latest-dev.sql

@@ -161,4 +161,21 @@ DROP FUNCTION IF EXISTS _timescaledb_functions.get_chunk_colstats;
 DROP FUNCTION IF EXISTS _timescaledb_internal.get_chunk_relstats;
 DROP FUNCTION IF EXISTS _timescaledb_internal.get_chunk_colstats;
 
-
+# In old TSDB versions, we disabled autovacuum for compressed chunks 
+# to keep the statistics. However, this restriction was removed in 
+# #5118 but no migration was performed to enable autovacuum
+# for existing chunks.
+DO $$
+DECLARE
+  chunk regclass;
+BEGIN
+  FOR chunk IN
+  SELECT format('%I.%I', schema_name, table_name)::regclass
+    FROM _timescaledb_catalog.chunk WHERE compressed_chunk_id IS NOT NULL
+  LOOP
+    EXECUTE format('ALTER TABLE %s RESET (autovacuum_enabled);', chunk::text)
+;
+  END LOOP;
+END
+$$;
+DO