Bug #22486025 INNODB: FAILING ASSERTION: KEY_LEN != 0 || FIND_FLAG !=…

… HA_READ_KEY_EXACT

This assertion basically comes because innodb doesn't support
index on zero length column.This problem comes only for
innodb intrinsic temporary table. It was decided that we will
presently return an error for the queries which build a
index on a zero length column . Supporting the index on
zero length column will be taken as a separate bug.

mysql-test/r/group_by.result

@@ -2108,8 +2108,7 @@ SET BIG_TABLES=1;
 CREATE TABLE t1(a INT);
 INSERT INTO t1 VALUES (0),(0);
 SELECT 1 FROM t1 GROUP BY IF(`a`,'','');
-1
-1
+ERROR 42000: The used storage engine can't index column 'tmp_field_0'
 SELECT 1 FROM t1 GROUP BY TRIM(LEADING RAND() FROM '');
 1
 1

mysql-test/t/group_by.test

@@ -1374,6 +1374,7 @@ DROP TABLE t1;
 SET BIG_TABLES=1;
 CREATE TABLE t1(a INT);
 INSERT INTO t1 VALUES (0),(0);
+--error ER_WRONG_KEY_COLUMN
 SELECT 1 FROM t1 GROUP BY IF(`a`,'','');
 SELECT 1 FROM t1 GROUP BY TRIM(LEADING RAND() FROM '');
 SELECT 1 FROM t1 GROUP BY SUBSTRING('',SLEEP(0),'');

storage/innobase/handler/ha_innodb.cc

@@ -10354,6 +10354,12 @@ create_index(
 	/* Assert that "GEN_CLUST_INDEX" cannot be used as non-primary index */
 	ut_a(innobase_strcasecmp(key->name, innobase_index_reserve_name) != 0);
 
+	if(key->key_length == 0) {
+		my_error(ER_WRONG_KEY_COLUMN,
+			 MYF(0),
+			 key->key_part->field->field_name);
+		DBUG_RETURN(ER_WRONG_KEY_COLUMN);
+	}
 	ind_type = 0;
 	if (key->flags & HA_SPATIAL) {
 		ind_type = DICT_SPATIAL;