Fixed bug in UNION when doing UNION with the same tables

myisam/mi_extra.c:
  More debugging information
mysql-test/r/union.result:
  Added test for UNION bug
mysql-test/t/union.test:
  Added test for UNION bug
sql/sql_base.cc:
  Clear field->query_id when using UNION
sql/sql_parse.cc:
  Fix for UNION bug
sql/sql_union.cc:
  Cleanup
sql/table.h:
  Fix for UNION bug
tools/Makefile.am:
  Fix for compiling with MIT-threads

myisam/mi_extra.c

@@ -34,6 +34,7 @@ int mi_extra(MI_INFO *info, enum ha_extra_function function)
   int error=0;
   MYISAM_SHARE *share=info->s;
   DBUG_ENTER("mi_extra");
+  DBUG_PRINT("enter",("function: %d",(int) function));
 
   switch (function) {
   case HA_EXTRA_RESET:

mysql-test/r/union.result

@@ -62,7 +62,11 @@ t2	ALL	NULL	NULL	NULL	NULL	4
 pseudo
 dekad
 joce
+pseudo1
+joce
+testtt
+tsestset
 pseudo	pseudo1	same
-dekad	joce	1
-joce	testtt	1
 joce	tsestset	1
+joce	testtt	1
+dekad	joce	1

mysql-test/t/union.test

@@ -60,5 +60,6 @@ CREATE TABLE t1 (
 ) TYPE=MyISAM;
 INSERT INTO t1 (pseudo,pseudo1,same) VALUES ('joce', 'testtt', 1),('joce', 'tsestset', 1),('dekad', 'joce', 1);
 SELECT pseudo FROM t1 WHERE pseudo1='joce' UNION SELECT pseudo FROM t1 WHERE pseudo='joce';
-SELECT * FROM t1 WHERE pseudo1='joce' UNION SELECT * FROM t1 WHERE pseudo='joce';
+SELECT pseudo1 FROM t1 WHERE pseudo1='joce' UNION SELECT pseudo1 FROM t1 WHERE pseudo='joce';
+SELECT * FROM t1 WHERE pseudo1='joce' UNION SELECT * FROM t1 WHERE pseudo='joce' order by pseudo desc;
 drop table t1;

sql/sql_base.cc

@@ -1590,7 +1590,8 @@ Field *find_field_in_table(THD *thd,TABLE *table,const char *name,uint length,
     else
       thd->dupp_field=field;
   }
-  if (check_grants && !thd->master_access && check_grant_column(thd,table,name,length))
+  if (check_grants && !thd->master_access &&
+      check_grant_column(thd,table,name,length))
     return WRONG_GRANT;
   return field;
 }
@@ -1808,6 +1809,12 @@ bool setup_tables(TABLE_LIST *tables)
 	DBUG_RETURN(1);
       table->keys_in_use_for_query &= ~map;
     }
+    if (table_list->shared)
+    {
+      /* Clear query_id that may have been set by previous select */
+      for (Field **ptr=table->field ; *ptr ; ptr++)
+	(*ptr)->query_id=0;
+    }
   }
   if (tablenr > MAX_TABLES)
   {

sql/sql_parse.cc

@@ -2923,6 +2923,8 @@ static bool create_total_list(THD *thd, LEX *lex, TABLE_LIST **result)
 	  new_table_list= &cursor->next;
 	  *new_table_list=0;			// end result list
 	}
+	else
+	  aux->shared=1;			// Mark that it's used twice
 	aux->table=(TABLE *) cursor;
       }
     }

sql/sql_union.cc

@@ -37,7 +37,7 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
   int res;
   DBUG_ENTER("mysql_union");
 
-  /* Fix tables--to-be-unioned-from list to point at opened tables */
+  /* Fix tables 'to-be-unioned-from' list to point at opened tables */
   for (sl=&lex->select_lex; sl; sl=sl->next)
   {
     for (TABLE_LIST *cursor= (TABLE_LIST *)sl->table_list.first;

sql/table.h

@@ -145,6 +145,7 @@ typedef struct st_table_list {
   uint		outer_join;			/* Which join type */
   bool		straight;			/* optimize with prev table */
   bool          updating;     /* for replicate-do/ignore table */
+  bool		shared;				/* Used twice in union */
 } TABLE_LIST;
 
 typedef struct st_open_table_list

tools/Makefile.am

 INCLUDES =		@MT_INCLUDES@ -I$(srcdir)/../include \
 			$(openssl_includes) -I../include
-LIBS=			@openssl_libs@
-LDADD=			@CLIENT_EXTRA_LDFLAGS@ ../libmysql_r/libmysqlclient_r.la
+LDADD=			@CLIENT_EXTRA_LDFLAGS@ ../libmysql_r/libmysqlclient_r.la @openssl_libs@
 bin_PROGRAMS=		mysqlmanager
 mysqlmanager_SOURCES=	mysqlmanager.c
 mysqlmanager_DEPENDENCIES=	$(LIBRARIES) $(pkglib_LTLIBRARIES)