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:
  A test case for WL#3456.
mysql-test/t/merge.test:
  A test case for WL#3456.
sql/ha_myisam.cc:
  Moved a part of code that converts TABLE object to MyISAM key and column
  definition to a separate function.
  
  Added check_definition() function that compares MyISAM table definitions.
sql/ha_myisammrg.cc:
  Check if underlying table definition conforms to merge table definition,
  and in case underlying table definition differs, refuse to open merge
  table.

1 files changed, 21 insertions, 1 deletions

diff --git a/mysql-test/r/merge.result b/mysql-test/r/merge.result
index a1ef7597143..eb333cdadb7 100644
--- a/mysql-test/r/merge.result
+++ b/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;