BUG#5390 - problems with merge tables

Problem #1: INSERT...SELECT, Version for 4.1.
INSERT ... SELECT with the same table on both sides (hidden
below a MERGE table) does now work by buffering the select result.
The duplicate detection works now after open_and_lock_tables() 
on the locks.
I did not find a test case that failed without the change in
sql_update.cc. I made the change anyway as it should in theory
fix a possible MERGE table problem with multi-table update.


libmysqld/ha_blackhole.cc:
  BUG#5390 - problems with merge tables
  No idea, how the symlink change made it into my patch.
mysql-test/r/create.result:
  BUG#5390 - problems with merge tables
  Removed a duplicate test.
mysql-test/r/merge.result:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT, Version for 4.1.
  Added test results.
mysql-test/t/create.test:
  BUG#5390 - problems with merge tables
  Removed a duplicate test.
mysql-test/t/merge.test:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT, Version for 4.1.
  Added tests.
sql/lock.cc:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT, Version for 4.1.
  Added a new function to find a duplicate lock in a list of tables.
sql/mysql_priv.h:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT, Version for 4.1.
  Added a declaration for the new function.
sql/sql_parse.cc:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT, Version for 4.1.
  Changed the duplicate tables detection for INSERT ... SELECT
  to use the new function, which does also work for MERGE tables.
sql/sql_update.cc:
  BUG#5390 - problems with merge tables
  Problem #1: INSERT...SELECT, Version for 4.1.
  Changed the duplicate tables detection for UPDATE
  to use the new function, which does also work for MERGE tables.

mysql-test/r/create.result

@@ -247,21 +247,6 @@ select * from t1;
 0	1	2
 0	0	1
 drop table t1;
-create table t1 select 1,2,3;
-create table if not exists t1 select 1,2;
-Warnings:
-Note	1050	Table 't1' already exists
-create table if not exists t1 select 1,2,3,4;
-ERROR 21S01: Column count doesn't match value count at row 1
-create table if not exists t1 select 1;
-Warnings:
-Note	1050	Table 't1' already exists
-select * from t1;
-1	2	3
-1	2	3
-0	1	2
-0	0	1
-drop table t1;
 create table t1 (a int not null, b int, primary key (a));
 insert into t1 values (1,1);
 create table if not exists t1 select 2;

mysql-test/r/merge.result

@@ -717,3 +717,52 @@ SELECT b FROM t2;
 b
 3
 DROP TABLE t1, t2;
+create table t1(a int);
+create table t2(a int);
+insert into t1 values (1);
+insert into t2 values (2);
+create table t3 (a int) engine=merge union=(t1, t2) insert_method=first;
+select * from t3;
+a
+1
+2
+insert t2 select * from t2;
+select * from t2;
+a
+2
+2
+insert t3 select * from t1;
+select * from t3;
+a
+1
+1
+2
+2
+insert t1 select * from t3;
+select * from t1;
+a
+1
+1
+1
+1
+2
+2
+select * from t2;
+a
+2
+2
+select * from t3;
+a
+1
+1
+1
+1
+2
+2
+2
+2
+check table t1, t2;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+test.t2	check	status	OK
+drop table t1, t2, t3;

mysql-test/t/create.test

@@ -200,13 +200,6 @@ drop table t1;
 # bug #1434
 #
 
-create table t1 select 1,2,3;
-create table if not exists t1 select 1,2;
---error 1136
-create table if not exists t1 select 1,2,3,4;
-create table if not exists t1 select 1;
-select * from t1;
-drop table t1;
 create table t1 select 1,2,3;
 create table if not exists t1 select 1,2;
 --error 1136

mysql-test/t/merge.test

@@ -350,4 +350,30 @@ INSERT INTO t2 (b) VALUES (1) ON DUPLICATE KEY UPDATE b=3;
 SELECT b FROM t2;
 DROP TABLE t1, t2;
 
+
+#
+# BUG#5390 - problems with merge tables
+# Problem #1: INSERT...SELECT
+#
+#drop table if exists t1, t2, t3;
+create table t1(a int);
+create table t2(a int);
+insert into t1 values (1);
+insert into t2 values (2);
+create table t3 (a int) engine=merge union=(t1, t2) insert_method=first;
+select * from t3;
+#
+insert t2 select * from t2;
+select * from t2;
+#
+insert t3 select * from t1;
+select * from t3;
+#
+insert t1 select * from t3;
+select * from t1;
+select * from t2;
+select * from t3;
+check table t1, t2;
+drop table t1, t2, t3;
+
 # End of 4.1 tests

sql/lock.cc

@@ -394,6 +394,88 @@ MYSQL_LOCK *mysql_lock_merge(MYSQL_LOCK *a,MYSQL_LOCK *b)
 }
 
 
+/*
+  Find duplicate lock in tables.
+
+  SYNOPSIS
+    mysql_lock_have_duplicate()
+    thd                         The current thread.
+    table                       The table to check for duplicate lock.
+    tables                      The list of tables to search for the dup lock.
+
+  NOTE
+    This is mainly meant for MERGE tables in INSERT ... SELECT
+    situations. The 'real', underlying tables can be found only after
+    the table is opened. The easier way is to check this after the
+    tables are locked.
+
+  RETURN
+    1           A table from 'tables' matches a lock on 'table'.
+    0           No duplicate lock is present.
+    -1          Error.
+*/
+
+int mysql_lock_have_duplicate(THD *thd, TABLE *table, TABLE_LIST *tables)
+{
+  uint                  count;
+  MYSQL_LOCK            *sql_lock1;
+  MYSQL_LOCK            *sql_lock2;
+  TABLE                 **tables1= &table;
+  TABLE                 **tables2;
+  TABLE                 **table_ptr;
+  TABLE_LIST            *tablist2;
+  TABLE                 *write_lock_used;
+  THR_LOCK_DATA         **lock_data1;
+  THR_LOCK_DATA         **end_data1;
+  THR_LOCK_DATA         **lock_data2;
+  THR_LOCK_DATA         **end_data2;
+  THR_LOCK              *lock1;
+  DBUG_ENTER("mysql_lock_have_duplicate");
+
+  if (! (sql_lock1= get_lock_data(thd, tables1, 1, 1, &write_lock_used)))
+    goto err0;
+
+  count=0;
+  for (tablist2 = tables; tablist2; tablist2= tablist2->next)
+    count++;
+  if (! (tables2= (TABLE**) sql_alloc(sizeof(TABLE*) * count)))
+    goto err1;
+  table_ptr= tables2;
+  for (tablist2 = tables; tablist2; tablist2= tablist2->next)
+    *(table_ptr++)= tablist2->table;
+  if (! (sql_lock2= get_lock_data(thd, tables2, count, 1, &write_lock_used)))
+    goto err1;
+
+  count= 1;
+  for (lock_data1= sql_lock1->locks,
+         end_data1= lock_data1 + sql_lock1->lock_count;
+       lock_data1 < end_data1;
+       lock_data1++)
+  {
+    lock1= (*lock_data1)->lock;
+    for (lock_data2= sql_lock2->locks,
+           end_data2= lock_data2 + sql_lock2->lock_count;
+         lock_data2 < end_data2;
+         lock_data2++)
+    {
+      if ((*lock_data2)->lock == lock1)
+        goto end;
+    }
+  }
+  count= 0;
+
+ end:
+  my_free((gptr) sql_lock2, MYF(0));
+  my_free((gptr) sql_lock1, MYF(0));
+  DBUG_RETURN(count);
+
+ err1:
+  my_free((gptr) sql_lock1, MYF(0));
+ err0:
+  DBUG_RETURN(-1);
+}
+
+
 	/* unlock a set of external */
 
 static int unlock_external(THD *thd, TABLE **table,uint count)
@@ -430,6 +512,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
   MYSQL_LOCK *sql_lock;
   THR_LOCK_DATA **locks;
   TABLE **to;
+  DBUG_ENTER("get_lock_data");
 
   *write_lock_used=0;
   for (i=tables=lock_count=0 ; i < count ; i++)
@@ -445,7 +528,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
 	my_malloc(sizeof(*sql_lock)+
 		  sizeof(THR_LOCK_DATA*)*tables+sizeof(table_ptr)*lock_count,
 		  MYF(0))))
-    return 0;
+    DBUG_RETURN(0);
   locks=sql_lock->locks=(THR_LOCK_DATA**) (sql_lock+1);
   to=sql_lock->table=(TABLE**) (locks+tables);
   sql_lock->table_count=lock_count;
@@ -465,7 +548,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
       {
 	my_error(ER_OPEN_AS_READONLY,MYF(0),table->table_name);
 	my_free((gptr) sql_lock,MYF(0));
-	return 0;
+	DBUG_RETURN(0);
       }
     }
     THR_LOCK_DATA **org_locks = locks;
@@ -475,7 +558,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
       for ( ; org_locks != locks ; org_locks++)
 	(*org_locks)->debug_print_param= (void *) table;
   }
-  return sql_lock;
+  DBUG_RETURN(sql_lock);
 }
 
 

sql/mysql_priv.h

@@ -1022,6 +1022,7 @@ void mysql_lock_remove(THD *thd, MYSQL_LOCK *locked,TABLE *table);
 void mysql_lock_abort(THD *thd, TABLE *table);
 bool mysql_lock_abort_for_thread(THD *thd, TABLE *table);
 MYSQL_LOCK *mysql_lock_merge(MYSQL_LOCK *a,MYSQL_LOCK *b);
+int mysql_lock_have_duplicate(THD *thd, TABLE *table, TABLE_LIST *tables);
 bool lock_global_read_lock(THD *thd);
 void unlock_global_read_lock(THD *thd);
 bool wait_if_global_read_lock(THD *thd, bool abort_on_refresh, bool is_not_commit);

sql/sql_parse.cc

@@ -2897,16 +2897,17 @@ mysql_execute_command(THD *thd)
     if (unit->select_limit_cnt < select_lex->select_limit)
       unit->select_limit_cnt= HA_POS_ERROR;		// No limit
 
-    if (find_real_table_in_list(tables->next, tables->db, tables->real_name))
+    if ((res= open_and_lock_tables(thd, tables)))
+      break;
+
+    insert_table= tables->table;
+    /* MERGE sub-tables can only be detected after open. */
+    if (mysql_lock_have_duplicate(thd, insert_table, tables->next))
     {
       /* Using same table for INSERT and SELECT */
       select_lex->options |= OPTION_BUFFER_RESULT;
     }
 
-    if ((res= open_and_lock_tables(thd, tables)))
-      break;
-      
-    insert_table= tables->table;
     /* Skip first table, which is the table we are inserting in */
     select_lex->table_list.first= (byte*) first_local_table->next;
     tables= (TABLE_LIST *) select_lex->table_list.first;

sql/sql_update.cc

@@ -854,8 +854,7 @@ int multi_update::prepare(List<Item> &not_used_values,
   {
     TABLE *table=table_ref->table;
     if (!(tables_to_update & table->map) && 
-	find_real_table_in_list(update_tables, table_ref->db,
-				table_ref->real_name))
+	mysql_lock_have_duplicate(thd, table, update_tables))
       table->no_cache= 1;			// Disable row cache
   }
   DBUG_RETURN(thd->is_fatal_error != 0);