MDEV-18149 Crash after DROP COLUMN of AUTO_INCREMENT column on nonempty table

commit_cache_norebuild(): Restore the MDEV-17901 fix that was reverted
as part of the MDEV-18076/MDEV-18077 fix. It was not redundant after all.

mysql-test/suite/innodb/r/instant_alter.result

@@ -578,6 +578,15 @@ id	f
 1	NULL
 2	NULL
 DROP TABLE t1;
+CREATE TABLE t1 (id INT NOT NULL AUTO_INCREMENT, f INT, KEY(id)) ENGINE=InnoDB ROW_FORMAT=REDUNDANT;
+INSERT INTO t1 SET f=NULL;
+ALTER TABLE t1 DROP COLUMN id;
+INSERT INTO t1 SET f=NULL;
+SELECT * FROM t1;
+f
+NULL
+NULL
+DROP TABLE t1;
 CREATE TABLE t1(f INT, k INT NOT NULL AUTO_INCREMENT, KEY(k)) ENGINE=InnoDB ROW_FORMAT=REDUNDANT;
 ALTER TABLE t1 DROP COLUMN f;
 INSERT INTO t1 VALUES (1);
@@ -1239,6 +1248,15 @@ id	f
 1	NULL
 2	NULL
 DROP TABLE t1;
+CREATE TABLE t1 (id INT NOT NULL AUTO_INCREMENT, f INT, KEY(id)) ENGINE=InnoDB ROW_FORMAT=COMPACT;
+INSERT INTO t1 SET f=NULL;
+ALTER TABLE t1 DROP COLUMN id;
+INSERT INTO t1 SET f=NULL;
+SELECT * FROM t1;
+f
+NULL
+NULL
+DROP TABLE t1;
 CREATE TABLE t1(f INT, k INT NOT NULL AUTO_INCREMENT, KEY(k)) ENGINE=InnoDB ROW_FORMAT=COMPACT;
 ALTER TABLE t1 DROP COLUMN f;
 INSERT INTO t1 VALUES (1);
@@ -1900,6 +1918,15 @@ id	f
 1	NULL
 2	NULL
 DROP TABLE t1;
+CREATE TABLE t1 (id INT NOT NULL AUTO_INCREMENT, f INT, KEY(id)) ENGINE=InnoDB ROW_FORMAT=DYNAMIC;
+INSERT INTO t1 SET f=NULL;
+ALTER TABLE t1 DROP COLUMN id;
+INSERT INTO t1 SET f=NULL;
+SELECT * FROM t1;
+f
+NULL
+NULL
+DROP TABLE t1;
 CREATE TABLE t1(f INT, k INT NOT NULL AUTO_INCREMENT, KEY(k)) ENGINE=InnoDB ROW_FORMAT=DYNAMIC;
 ALTER TABLE t1 DROP COLUMN f;
 INSERT INTO t1 VALUES (1);
@@ -2042,5 +2069,5 @@ SELECT variable_value-@old_instant instants
 FROM information_schema.global_status
 WHERE variable_name = 'innodb_instant_alter_column';
 instants
-155
+158
 SET GLOBAL innodb_purge_rseg_truncate_frequency= @saved_frequency;

mysql-test/suite/innodb/t/instant_alter.test

@@ -447,6 +447,14 @@ ALTER TABLE t1 ADD COLUMN id INT NOT NULL AUTO_INCREMENT FIRST, ADD KEY(id);
 SELECT * FROM t1;
 DROP TABLE t1;
 
+# MDEV-18149 Crash after DROP COLUMN of AUTO_INCREMENT column on nonempty table
+eval CREATE TABLE t1 (id INT NOT NULL AUTO_INCREMENT, f INT, KEY(id)) $engine;
+INSERT INTO t1 SET f=NULL;
+ALTER TABLE t1 DROP COLUMN id;
+INSERT INTO t1 SET f=NULL;
+SELECT * FROM t1;
+DROP TABLE t1;
+
 # MDEV-18076/MDEV-18077 Crash on AUTO_INCREMENT column after instant DROP
 eval CREATE TABLE t1(f INT, k INT NOT NULL AUTO_INCREMENT, KEY(k)) $engine;
 ALTER TABLE t1 DROP COLUMN f;

storage/innobase/handler/handler0alter.cc

 /*****************************************************************************
 
 Copyright (c) 2005, 2018, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2013, 2018, MariaDB Corporation.
+Copyright (c) 2013, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -10359,6 +10359,10 @@ commit_cache_norebuild(
 				}
 			}
 		}
+
+		if (!ctx->instant_table->persistent_autoinc) {
+			ctx->new_table->persistent_autoinc = 0;
+		}
 	}
 
 	if (ha_alter_info->handler_flags & ALTER_COLUMN_UNVERSIONED) {