BUG#18233 - Memory tables INDEX USING HASH (a,b) returns 1 row on

            SELECT WHERE a= AND b=

Selecting data from memory table with varchar column and hash index over it
returns only first row matched.

Problem was that key length calculation for varchar columns didn't include
number of bytes to store length.

Fixed key length for varchar fields to include number of bytes to store length.

heap/hp_create.c

@@ -85,6 +85,7 @@ int heap_create(const char *name, uint keys, HP_KEYDEF *keydef,
           if (!my_binary_compare(keyinfo->seg[j].charset))
             keyinfo->flag|= HA_END_SPACE_KEY;
           keyinfo->flag|= HA_VAR_LENGTH_KEY;
+          length+= 2;
           /* Save number of bytes used to store length */
           keyinfo->seg[j].bit_start= 1;
           break;
@@ -95,6 +96,7 @@ int heap_create(const char *name, uint keys, HP_KEYDEF *keydef,
           if (!my_binary_compare(keyinfo->seg[j].charset))
             keyinfo->flag|= HA_END_SPACE_KEY;
           keyinfo->flag|= HA_VAR_LENGTH_KEY;
+          length+= 2;
           /* Save number of bytes used to store length */
           keyinfo->seg[j].bit_start= 2;
           /*

mysql-test/r/heap.result

@@ -718,3 +718,16 @@ Name	Engine	Version	Row_format	Rows	Avg_row_length	Data_length	Max_data_length	I
 t1	MEMORY	10	Fixed	0	11	0	#	0	0	NULL	NULL	NULL	NULL	latin1_swedish_ci	NULL		
 t2	MEMORY	10	Fixed	0	12	0	#	0	0	NULL	NULL	NULL	NULL	latin1_swedish_ci	NULL		
 drop table t1, t2;
+CREATE TABLE t1(a VARCHAR(1), b VARCHAR(2), c VARCHAR(256),
+KEY(a), KEY(b), KEY(c)) ENGINE=MEMORY;
+INSERT INTO t1 VALUES('a','aa',REPEAT('a', 256)),('a','aa',REPEAT('a',256));
+SELECT COUNT(*) FROM t1 WHERE a='a';
+COUNT(*)
+2
+SELECT COUNT(*) FROM t1 WHERE b='aa';
+COUNT(*)
+2
+SELECT COUNT(*) FROM t1 WHERE c=REPEAT('a',256);
+COUNT(*)
+2
+DROP TABLE t1;

mysql-test/t/heap.test

@@ -458,4 +458,16 @@ create table t2 (c varchar(10)) engine=memory;
 show table status like 't_';
 drop table t1, t2;
 
+#
+# BUG#18233 - Memory tables INDEX USING HASH (a,b) returns 1 row on
+#             SELECT WHERE a= AND b=
+#
+CREATE TABLE t1(a VARCHAR(1), b VARCHAR(2), c VARCHAR(256),
+                KEY(a), KEY(b), KEY(c)) ENGINE=MEMORY;
+INSERT INTO t1 VALUES('a','aa',REPEAT('a', 256)),('a','aa',REPEAT('a',256));
+SELECT COUNT(*) FROM t1 WHERE a='a';
+SELECT COUNT(*) FROM t1 WHERE b='aa';
+SELECT COUNT(*) FROM t1 WHERE c=REPEAT('a',256);
+DROP TABLE t1;
+
 # End of 5.0 tests