branches/5.1: Add test cases and fix a bug where the last AUTOINC cached value

was not reset to 0 when the table was truncated.

Bug #37531 : After truncate, auto_increment behaves incorrectly for InnoDB

handler/ha_innodb.cc

@@ -5817,6 +5817,14 @@ ha_innobase::info(
 		if (thd_sql_command(user_thd) == SQLCOM_TRUNCATE) {
 
 			n_rows = 0;
+
+			/* We need to reset the prebuilt value too, otherwise
+			checks for values greater than the last value written
+			to the table will fail and the autoinc counter will
+			not be updated. This will force write_row() into
+			attempting an update of the table's AUTOINC counter. */
+
+			prebuilt->last_value = 0;
 		}
 
 		stats.records = (ha_rows)n_rows;

mysql-test/innodb-autoinc.result

@@ -87,3 +87,85 @@ SELECT * FROM t1;
 c1	c2
 18446744073709551615	NULL
 DROP TABLE t1;
+CREATE TABLE t1(c1 INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+c1
+1
+2
+3
+4
+5
+6
+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=7 DEFAULT CHARSET=latin1
+TRUNCATE TABLE t1;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` int(11) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`c1`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+c1
+1
+2
+3
+4
+5
+6
+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=7 DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1(c1 INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+c1
+1
+2
+3
+4
+5
+6
+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=7 DEFAULT CHARSET=latin1
+DELETE FROM t1;
+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=7 DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+c1
+1
+2
+3
+7
+8
+9
+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=10 DEFAULT CHARSET=latin1
+DROP TABLE t1;

mysql-test/innodb-autoinc.test

@@ -105,3 +105,37 @@ INSERT INTO t1 VALUES (18446744073709551615, null);
 INSERT INTO t1 (c2) VALUES ('innodb');
 SELECT * FROM t1;
 DROP TABLE t1;
+
+#
+# Bug 37531
+# After truncate, auto_increment behaves incorrectly for InnoDB
+#
+CREATE TABLE t1(c1 INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+SHOW CREATE TABLE t1;
+TRUNCATE TABLE t1;
+SHOW CREATE TABLE t1;
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+#
+# Deleting all records should not reset the AUTOINC counter.
+#
+CREATE TABLE t1(c1 INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+SHOW CREATE TABLE t1;
+DELETE FROM t1;
+SHOW CREATE TABLE t1;
+INSERT INTO t1 VALUES (1), (2), (3);
+INSERT INTO t1 VALUES (NULL), (NULL), (NULL);
+SELECT c1 FROM t1;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+