WL#3567 - MERGE engine: a check for underlying table conformance

When a merge table is opened compare column and key definition of
underlying tables against column and key definition of merge table.

If any of underlying tables have different column/key definition
refuse to open merge table.

mysql-test/r/merge.result

@@ -770,7 +770,7 @@ CREATE TABLE t1(a INT);
 INSERT INTO t1 VALUES(2),(1);
 CREATE TABLE t2(a INT, KEY(a)) ENGINE=MERGE UNION=(t1);
 SELECT * FROM t2 WHERE a=2;
-ERROR HY000: Got error 124 from storage engine
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
 DROP TABLE t1, t2;
 CREATE TABLE t1(a INT) ENGINE=MEMORY;
 CREATE TABLE t2(a INT) ENGINE=MERGE UNION=(t1);
@@ -781,3 +781,23 @@ CREATE TABLE t2(a INT) ENGINE=MERGE UNION=(t3);
 SELECT * FROM t2;
 ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
 DROP TABLE t2;
+CREATE TABLE t1(a INT, b TEXT);
+CREATE TABLE tm1(a TEXT, b INT) ENGINE=MERGE UNION=(t1);
+SELECT * FROM tm1;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+DROP TABLE t1, tm1;
+CREATE TABLE t1(a SMALLINT, b SMALLINT);
+CREATE TABLE tm1(a INT) ENGINE=MERGE UNION=(t1);
+SELECT * FROM tm1;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+DROP TABLE t1, tm1;
+CREATE TABLE t1(a SMALLINT, b SMALLINT, KEY(a, b));
+CREATE TABLE tm1(a SMALLINT, b SMALLINT, KEY(a)) ENGINE=MERGE UNION=(t1);
+SELECT * FROM tm1;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+DROP TABLE t1, tm1;
+CREATE TABLE t1(a SMALLINT, b SMALLINT, KEY(b));
+CREATE TABLE tm1(a SMALLINT, b SMALLINT, KEY(a)) ENGINE=MERGE UNION=(t1);
+SELECT * FROM tm1;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+DROP TABLE t1, tm1;

mysql-test/t/merge.test

@@ -383,7 +383,7 @@ drop table t1, t2, t3;
 CREATE TABLE t1(a INT);
 INSERT INTO t1 VALUES(2),(1);
 CREATE TABLE t2(a INT, KEY(a)) ENGINE=MERGE UNION=(t1);
---error 1030
+--error 1168
 SELECT * FROM t2 WHERE a=2;
 DROP TABLE t1, t2;
 
@@ -401,4 +401,31 @@ CREATE TABLE t2(a INT) ENGINE=MERGE UNION=(t3);
 SELECT * FROM t2;
 DROP TABLE t2;
 
+#
+# Underlying table definition conformance tests.
+#
+CREATE TABLE t1(a INT, b TEXT);
+CREATE TABLE tm1(a TEXT, b INT) ENGINE=MERGE UNION=(t1);
+--error 1168
+SELECT * FROM tm1;
+DROP TABLE t1, tm1;
+
+CREATE TABLE t1(a SMALLINT, b SMALLINT);
+CREATE TABLE tm1(a INT) ENGINE=MERGE UNION=(t1);
+--error 1168
+SELECT * FROM tm1;
+DROP TABLE t1, tm1;
+
+CREATE TABLE t1(a SMALLINT, b SMALLINT, KEY(a, b));
+CREATE TABLE tm1(a SMALLINT, b SMALLINT, KEY(a)) ENGINE=MERGE UNION=(t1);
+--error 1168
+SELECT * FROM tm1;
+DROP TABLE t1, tm1;
+
+CREATE TABLE t1(a SMALLINT, b SMALLINT, KEY(b));
+CREATE TABLE tm1(a SMALLINT, b SMALLINT, KEY(a)) ENGINE=MERGE UNION=(t1);
+--error 1168
+SELECT * FROM tm1;
+DROP TABLE t1, tm1;
+
 # End of 4.1 tests

sql/ha_myisammrg.cc

@@ -32,6 +32,13 @@
 ** MyISAM MERGE tables
 *****************************************************************************/
 
+extern int table2myisam(TABLE *table_arg, MI_KEYDEF **keydef_out,
+                        MI_COLUMNDEF **recinfo_out, uint *records_out);
+extern int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
+                            uint t1_keys, uint t1_recs,
+                            MI_KEYDEF *t2_keyinfo, MI_COLUMNDEF *t2_recinfo,
+                            uint t2_keys, uint t2_recs, bool strict);
+
 const char **ha_myisammrg::bas_ext() const
 { static const char *ext[]= { ".MRG", NullS }; return ext; }
 
@@ -49,6 +56,12 @@ const char *ha_myisammrg::index_type(uint key_number)
 
 int ha_myisammrg::open(const char *name, int mode, uint test_if_locked)
 {
+  MI_KEYDEF *keyinfo;
+  MI_COLUMNDEF *recinfo;
+  MYRG_TABLE *u_table;
+  uint recs;
+  uint keys= table->keys;
+  int error;
   char name_buff[FN_REFLEN];
 
   DBUG_PRINT("info", ("ha_myisammrg::open"));
@@ -69,20 +82,45 @@ int ha_myisammrg::open(const char *name, int mode, uint test_if_locked)
 
   if (table->reclength != mean_rec_length && mean_rec_length)
   {
-    DBUG_PRINT("error",("reclength: %d  mean_rec_length: %d",
+    DBUG_PRINT("error",("reclength: %d  mean_rec_length: %lu",
 			table->reclength, mean_rec_length));
+    error= HA_ERR_WRONG_MRG_TABLE_DEF;
+    goto err;
+  }
+  if ((error= table2myisam(table, &keyinfo, &recinfo, &recs)))
+  {
+    /* purecov: begin inspected */
+    DBUG_PRINT("error", ("Failed to convert TABLE object to MyISAM "
+                         "key and column definition"));
     goto err;
+    /* purecov: end */
   }
+  for (u_table= file->open_tables; u_table < file->end_table; u_table++)
+  {
+    if (check_definition(keyinfo, recinfo, keys, recs,
+                         u_table->table->s->keyinfo, u_table->table->s->rec,
+                         u_table->table->s->base.keys,
+                         u_table->table->s->base.fields, false))
+    {
+      my_free((gptr) recinfo, MYF(0));
+      error= HA_ERR_WRONG_MRG_TABLE_DEF;
+      goto err;
+    }
+  }
+  my_free((gptr) recinfo, MYF(0));
 #if !defined(BIG_TABLES) || SIZEOF_OFF_T == 4
   /* Merge table has more than 2G rows */
   if (table->crashed)
+  {
+    error= HA_ERR_WRONG_MRG_TABLE_DEF;
     goto err;
+  }
 #endif
   return (0);
 err:
   myrg_close(file);
   file=0;
-  return (my_errno= HA_ERR_WRONG_MRG_TABLE_DEF);
+  return (my_errno= error);
 }
 
 int ha_myisammrg::close(void)