diff --git a/contrib/test_decoding/expected/oldest_xmin.out b/contrib/test_decoding/expected/oldest_xmin.out
index d09342c4be..d1b4f17e3a 100644
--- a/contrib/test_decoding/expected/oldest_xmin.out
+++ b/contrib/test_decoding/expected/oldest_xmin.out
@@ -1,6 +1,6 @@
 Parsed test spec with 2 sessions
 
-starting permutation: s0_begin s0_getxid s1_begin s1_insert s0_alter s0_commit s0_checkpoint s0_get_changes s1_commit s0_vacuum s0_get_changes
+starting permutation: s0_begin s0_getxid s1_begin s1_insert s0_alter s0_commit s0_checkpoint s0_get_changes s0_get_changes s1_commit s0_vacuum s0_get_changes
 step s0_begin: BEGIN;
 step s0_getxid: SELECT txid_current() IS NULL;
 ?column?       
@@ -14,8 +14,11 @@ step s0_checkpoint: CHECKPOINT;
 step s0_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
 data           
 
+step s0_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+data           
+
 step s1_commit: COMMIT;
-step s0_vacuum: VACUUM FULL;
+step s0_vacuum: VACUUM pg_attribute;
 step s0_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
 data           
 
diff --git a/contrib/test_decoding/specs/oldest_xmin.spec b/contrib/test_decoding/specs/oldest_xmin.spec
index 4f8af70aa2..141fe2b145 100644
--- a/contrib/test_decoding/specs/oldest_xmin.spec
+++ b/contrib/test_decoding/specs/oldest_xmin.spec
@@ -22,7 +22,7 @@ step "s0_getxid" { SELECT txid_current() IS NULL; }
 step "s0_alter" { ALTER TYPE basket DROP ATTRIBUTE mangos; }
 step "s0_commit" { COMMIT; }
 step "s0_checkpoint" { CHECKPOINT; }
-step "s0_vacuum" { VACUUM FULL; }
+step "s0_vacuum" { VACUUM pg_attribute; }
 step "s0_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1'); }
 
 session "s1"
@@ -30,8 +30,11 @@ step "s1_begin" { BEGIN; }
 step "s1_insert" { INSERT INTO harvest VALUES ((1, 2, 3)); }
 step "s1_commit" { COMMIT; }
 
-# Checkpoint with following get_changes forces to advance xmin. ALTER of a
+# Checkpoint with following get_changes forces xmin advancement. We do
+# get_changes twice because if one more xl_running_xacts record had slipped
+# before our CHECKPOINT, xmin will be advanced only on this record, thus not
+# reaching value needed for vacuuming corresponding pg_attribute entry. ALTER of
 # composite type is a rare form of DDL which allows T1 to see the tuple which
 # will be removed (xmax set) before T1 commits. That is, interlocking doesn't
 # forbid modifying catalog after someone read it (and didn't commit yet).
-permutation "s0_begin" "s0_getxid" "s1_begin" "s1_insert" "s0_alter" "s0_commit" "s0_checkpoint" "s0_get_changes" "s1_commit" "s0_vacuum" "s0_get_changes"
+permutation "s0_begin" "s0_getxid" "s1_begin" "s1_insert" "s0_alter" "s0_commit" "s0_checkpoint" "s0_get_changes" "s0_get_changes""s1_commit" "s0_vacuum" "s0_get_changes"