bk commit into 5.1 tree (istruewing:1.2568) BUG#35068

[Ingo Struewing]

Below is the list of changes that have just been committed into a local
5.1 repository of istruewing.  When istruewing does a push these changes
will be propagated to the main repository and, within 24 hours after the
push, to the public repository.
For information on how to access the public repository
see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2008-05-03 21:51:42+02:00, istruewing@stripped +3 -0
  Bug#35068 - Assertion fails when reading from i_s.tables
              and there is incorrect merge table
    
  SELECT * on INFORMATION_SCHEMA.TABLES crashed the server when
  a MERGE table included a non-existent MyISAM table.
    
  The MERGE table adds its children to the table list so that
  open_tables() opens them too. If a child cannot be opened,
  open_tables() returns with the open MERGE table and opened
  MyISAM tables as far as they could be opened. However, the
  returned error message is ER_NO_SUCH_TABLE.
    
  get_all_tables() from information schema assumed that it opens
  one table at a time. If it cannot be opened, and the error is
  ER_NO_SUCH_TABLE, it assumed that no table needs to be closed.
    
  Added condition !thd->open_tables to detect open failure
  of MERGE table. So if any table was opened, closing will
  not be skipped.

  mysql-test/r/merge.result@stripped, 2008-05-03 21:51:40+02:00, istruewing@stripped +6 -0
    Bug#35068 - Assertion fails when reading from i_s.tables
                and there is incorrect merge table
    Added test result.

  mysql-test/t/merge.test@stripped, 2008-05-03 21:51:40+02:00, istruewing@stripped +11 -0
    Bug#35068 - Assertion fails when reading from i_s.tables
                and there is incorrect merge table
    Added test.

  sql/sql_show.cc@stripped, 2008-05-03 21:51:40+02:00, istruewing@stripped +14 -1
    Bug#35068 - Assertion fails when reading from i_s.tables
                and there is incorrect merge table
    Added condition !thd->open_tables to detect open failure
    of MERGE table.

diff -Nrup a/mysql-test/r/merge.result b/mysql-test/r/merge.result
--- a/mysql-test/r/merge.result	2008-04-22 14:32:08 +02:00
+++ b/mysql-test/r/merge.result	2008-05-03 21:51:40 +02:00
@@ -2011,3 +2011,9 @@ test.t1	optimize	status	OK
 FLUSH TABLES m1, t1;
 UNLOCK TABLES;
 DROP TABLE t1, m1;
+CREATE TABLE tm1 (c1 INT) ENGINE=MRG_MYISAM UNION=(t1) INSERT_METHOD=FIRST;
+SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'test';
+TABLE_CATALOG	TABLE_SCHEMA	TABLE_NAME	TABLE_TYPE	ENGINE	VERSION	ROW_FORMAT	TABLE_ROWS	AVG_ROW_LENGTH	DATA_LENGTH	MAX_DATA_LENGTH	INDEX_LENGTH	DATA_FREE	AUTO_INCREMENT	CREATE_TIME	UPDATE_TIME	CHECK_TIME	TABLE_COLLATION	CHECKSUM	CREATE_OPTIONS	TABLE_COMMENT
+NULL	test	tm1	BASE TABLE	NULL	NULL	NULL	#	#	#	#	#	#	#	#	#	#	NULL	#	#	Table 'test.t1' doesn't exist
+DROP TABLE tm1;
+End of 5.1 tests
diff -Nrup a/mysql-test/t/merge.test b/mysql-test/t/merge.test
--- a/mysql-test/t/merge.test	2008-04-22 14:32:08 +02:00
+++ b/mysql-test/t/merge.test	2008-05-03 21:51:40 +02:00
@@ -1401,3 +1401,14 @@ FLUSH TABLES m1, t1;
 UNLOCK TABLES;
 DROP TABLE t1, m1;
 
+#
+# Bug#35068 - Assertion fails when reading from i_s.tables
+#             and there is incorrect merge table
+#
+CREATE TABLE tm1 (c1 INT) ENGINE=MRG_MYISAM UNION=(t1) INSERT_METHOD=FIRST;
+--replace_column 8 # 9 # 10 # 11 # 12 # 13 # 14 # 15 # 16 # 17 # 19 # 20 #
+SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'test';
+DROP TABLE tm1;
+
+--echo End of 5.1 tests
+
diff -Nrup a/sql/sql_show.cc b/sql/sql_show.cc
--- a/sql/sql_show.cc	2008-03-28 11:03:04 +01:00
+++ b/sql/sql_show.cc	2008-05-03 21:51:40 +02:00
@@ -3275,6 +3275,18 @@ int get_all_tables(THD *thd, TABLE_LIST 
             lex->sql_command= SQLCOM_SHOW_FIELDS;
             show_table_list->i_s_requested_object=
               schema_table->i_s_requested_object;
+            /*
+              Below we want to ignore non-existing tables.
+              ER_NO_SUCH_TABLE is not sufficient for a MERGE table if
+              one of the children does not exist. In this case we get
+              ER_NO_SUCH_TABLE, but thd->open_tables contains the MERGE
+              parent and perhaps some children. So we use the
+              combination of ER_NO_SUCH_TABLE && !thd->open_tables for
+              the final decision. Here we assert that thd->open_tables
+              is empty before we open the table. If this fails, we need
+              another condition to catch a MERGE table.
+            */
+            DBUG_ASSERT(!thd->open_tables);
             res= open_normal_and_derived_tables(thd, show_table_list,
                                                 MYSQL_LOCK_IGNORE_FLUSH);
             lex->sql_command= save_sql_command;
@@ -3287,7 +3299,8 @@ int get_all_tables(THD *thd, TABLE_LIST 
               for thd->main_da.sql_errno().
             */
             if (res && thd->is_error() &&
-                thd->main_da.sql_errno() == ER_NO_SUCH_TABLE)
+                thd->main_da.sql_errno() == ER_NO_SUCH_TABLE &&
+                !thd->open_tables)
             {
               /*
                 Hide error for not existing table.