MDEV-23345 Assertion not_redundant() == old.not_redundant()

In commit fd9ca2a7 (MDEV-23295)
we added a debug assertion, which caught a similar bug.

prepare_inplace_alter_table_dict(): If we had promised that
ALGORITHM=INPLACE or ALGORITHM=NOCOPY is supported, we must
preserve the ROW_FORMAT.

mysql-test/suite/innodb/r/default_row_format_alter,compact.rdiff

 --- default_row_format_alter.result
 +++ default_row_format_alter,compact.reject
-@@ -91,6 +91,6 @@
+@@ -91,7 +91,7 @@
  ALTER TABLE t1 ADD b INT;
  SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
  ROW_FORMAT
 -Dynamic
++Compact
+ DROP TABLE t1;
+ #
+ # MDEV-23345 Assertion not_redundant() == old.not_redundant() failed
+@@ -102,6 +102,6 @@
+ ALTER TABLE t1 DROP b;
+ SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
+ ROW_FORMAT
+-Dynamic
 +Compact
  DROP TABLE t1;
  SET GLOBAL innodb_default_row_format = @row_format;

mysql-test/suite/innodb/r/default_row_format_alter,redundant.rdiff

 --- default_row_format_alter.result
-+++ default_row_format_alter,compact.reject
-@@ -91,6 +91,6 @@
++++ default_row_format_alter,redundant.reject
+@@ -91,7 +91,7 @@
  ALTER TABLE t1 ADD b INT;
  SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
  ROW_FORMAT
 -Dynamic
++Redundant
+ DROP TABLE t1;
+ #
+ # MDEV-23345 Assertion not_redundant() == old.not_redundant() failed
+@@ -102,6 +102,6 @@
+ ALTER TABLE t1 DROP b;
+ SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
+ ROW_FORMAT
+-Dynamic
 +Redundant
  DROP TABLE t1;
  SET GLOBAL innodb_default_row_format = @row_format;

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

@@ -93,4 +93,15 @@ SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
 ROW_FORMAT
 Dynamic
 DROP TABLE t1;
+#
+# MDEV-23345 Assertion not_redundant() == old.not_redundant() failed
+#
+SET GLOBAL innodb_default_row_format = @row_format;
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT, KEY(b)) ENGINE=InnoDB;
+SET GLOBAL innodb_default_row_format= COMPACT;
+ALTER TABLE t1 DROP b;
+SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
+ROW_FORMAT
+Dynamic
+DROP TABLE t1;
 SET GLOBAL innodb_default_row_format = @row_format;

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

@@ -106,4 +106,14 @@ ALTER TABLE t1 ADD b INT;
 SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-23345 Assertion not_redundant() == old.not_redundant() failed
+--echo #
+SET GLOBAL innodb_default_row_format = @row_format;
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT, KEY(b)) ENGINE=InnoDB;
+SET GLOBAL innodb_default_row_format= COMPACT;
+ALTER TABLE t1 DROP b;
+SELECT ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='t1';
+DROP TABLE t1;
+
 SET GLOBAL innodb_default_row_format = @row_format;

storage/innobase/handler/handler0alter.cc

@@ -6209,9 +6209,13 @@ prepare_inplace_alter_table_dict(
 
 	user_table = ctx->new_table;
 
-	if (ha_alter_info->inplace_supported == HA_ALTER_INPLACE_INSTANT) {
-		/* If we promised ALGORITHM=INSTANT capability, we must
-		retain the original ROW_FORMAT of the table. */
+	switch (ha_alter_info->inplace_supported) {
+	default: break;
+	case HA_ALTER_INPLACE_INSTANT:
+	case HA_ALTER_INPLACE_NOCOPY_LOCK:
+	case HA_ALTER_INPLACE_NOCOPY_NO_LOCK:
+		/* If we promised ALGORITHM=NOCOPY or ALGORITHM=INSTANT,
+		we must retain the original ROW_FORMAT of the table. */
 		flags = (user_table->flags & (DICT_TF_MASK_COMPACT
 					      | DICT_TF_MASK_ATOMIC_BLOBS))
 			| (flags & ~(DICT_TF_MASK_COMPACT