Merge from mysql-5.1-innodb to mysql-5.5-innodb. Test was adjusted.

mysql-test/suite/innodb/r/innodb-autoinc-18274.result

+drop table if exists t1;
+SET @@SESSION.AUTO_INCREMENT_INCREMENT=1, @@SESSION.AUTO_INCREMENT_OFFSET=1;
+CREATE TABLE t1 (c1 INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (null);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` int(11) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`c1`)
+) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1
+DELETE FROM t1;
+OPTIMIZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	optimize	note	Table does not support optimize, doing recreate + analyze instead
+test.t1	optimize	status	OK
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` int(11) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`c1`)
+) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES(null);
+SELECT * FROM t1;
+c1
+2
+DROP TABLE t1;

mysql-test/suite/innodb/t/innodb-autoinc-18274.test

+-- source include/have_innodb.inc
+# embedded server ignores 'delayed', so skip this
+-- source include/not_embedded.inc
+
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+#
+# Bug #18274	InnoDB auto_increment field reset on OPTIMIZE TABLE
+SET @@SESSION.AUTO_INCREMENT_INCREMENT=1, @@SESSION.AUTO_INCREMENT_OFFSET=1;
+CREATE TABLE t1 (c1 INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (null);
+SHOW CREATE TABLE t1;
+DELETE FROM t1;
+OPTIMIZE TABLE t1;
+SHOW CREATE TABLE t1;
+INSERT INTO t1 VALUES(null);
+SELECT * FROM t1;
+DROP TABLE t1;
+
+#
+# restore environment to the state it was before this test execution
+#
+
+-- disable_query_log

storage/innobase/handler/ha_innodb.cc

@@ -7036,23 +7036,25 @@ ha_innobase::create(
 	setup at this stage and so we use thd. */
 
 	/* We need to copy the AUTOINC value from the old table if
-	this is an ALTER TABLE or CREATE INDEX because CREATE INDEX
-	does a table copy too. */
+	this is an ALTER|OPTIMIZE TABLE or CREATE INDEX because CREATE INDEX
+	does a table copy too. If query was one of :
+
+		CREATE TABLE ...AUTO_INCREMENT = x; or
+		ALTER TABLE...AUTO_INCREMENT = x;   or
+		OPTIMIZE TABLE t; or
+		CREATE INDEX x on t(...);
+
+	Find out a table definition from the dictionary and get
+	the current value of the auto increment field. Set a new
+	value to the auto increment field if the value is greater
+	than the maximum value in the column. */
 
 	if (((create_info->used_fields & HA_CREATE_USED_AUTO)
 	    || thd_sql_command(thd) == SQLCOM_ALTER_TABLE
+	    || thd_sql_command(thd) == SQLCOM_OPTIMIZE
 	    || thd_sql_command(thd) == SQLCOM_CREATE_INDEX)
 	    && create_info->auto_increment_value > 0) {
 
-		/* Query was one of :
-		CREATE TABLE ...AUTO_INCREMENT = x; or
-		ALTER TABLE...AUTO_INCREMENT = x;   or
-		CREATE INDEX x on t(...);
-		Find out a table definition from the dictionary and get
-		the current value of the auto increment field. Set a new
-		value to the auto increment field if the value is greater
-		than the maximum value in the column. */
-
 		auto_inc_value = create_info->auto_increment_value;
 
 		dict_table_autoinc_lock(innobase_table);