branches/5.1: Fix Bug# 34920. We need to use/inherit the passed in autoinc

counter for ALTER TABLE statements too.

handler/ha_innodb.cc

@@ -5109,8 +5109,15 @@ ha_innobase::create(
 
 	DBUG_ASSERT(innobase_table != 0);
 
-	if ((create_info->used_fields & HA_CREATE_USED_AUTO) &&
-	   (create_info->auto_increment_value != 0)) {
+	/* Note: We can't call update_thd() as prebuilt will not be
+	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. */
+
+	if (((create_info->used_fields & HA_CREATE_USED_AUTO)
+	    || thd_sql_command(thd) == SQLCOM_ALTER_TABLE)
+	    && create_info->auto_increment_value != 0) {
 
 		/* Query was ALTER TABLE...AUTO_INCREMENT = x; or
 		CREATE TABLE ...AUTO_INCREMENT = x; Find out a table

mysql-test/innodb.result

@@ -3231,3 +3231,22 @@ a
 2
 DROP TABLE t1;
 DROP TABLE t2;
+CREATE TABLE t1 (
+c1 INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+c2 VARCHAR(128) NOT NULL,
+PRIMARY KEY(c1)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=100;
+CREATE TABLE t2 (
+c1 INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+c2 INT(10) UNSIGNED DEFAULT NULL,
+PRIMARY KEY(c1)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=200;
+SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't2';
+AUTO_INCREMENT
+200
+ALTER TABLE t2 ADD CONSTRAINT t1_t2_1 FOREIGN KEY(c1) REFERENCES t1(c1);
+SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't2';
+AUTO_INCREMENT
+200
+DROP TABLE t2;
+DROP TABLE t1;

mysql-test/innodb.test

@@ -2415,6 +2415,29 @@ DROP TABLE t2;
 DISCONNECT c1;
 DISCONNECT c2;
 
+#
+# Bug 34920 test
+#
+CONNECTION default;
+CREATE TABLE t1 (
+	c1 INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+	c2 VARCHAR(128) NOT NULL,
+	PRIMARY KEY(c1)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=100;
+
+CREATE TABLE t2 (
+	c1 INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+	c2 INT(10) UNSIGNED DEFAULT NULL,
+	PRIMARY KEY(c1)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=200;
+
+SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't2';
+ALTER TABLE t2 ADD CONSTRAINT t1_t2_1 FOREIGN KEY(c1) REFERENCES t1(c1);
+SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't2';
+DROP TABLE t2;
+DROP TABLE t1;
+# End 34920 test
+
 #######################################################################
 #                                                                     #
 # Please, DO NOT TOUCH this file as well as the innodb.result file.   #