Bug#6031 - To drop database you have to execute DROP DATABASE command twice.

  DROP DATABASE failed because of file ext not in TYPELIB of known extensions.
  General solution - construct a TYPELIB at runtime instead of a static list.


mysql-test/r/ndb_basic.result:
  Bug#6031
    New test for bug
mysql-test/t/ndb_basic.test:
  Bug#6031
    New test for bug
sql/ha_ndbcluster.cc:
  Cosmetic fix
sql/handler.cc:
  Bug#6031
    New function - ha_known_exts()
    We can construct TYPELIB of known db file extensions.
sql/handler.h:
  Bug#6031
    New function - ha_known_exts()
sql/sql_db.cc:
  Bug#6031
    We use a constructed list of known extensions instead of a static list

mysql-test/r/ndb_basic.result

@@ -400,6 +400,13 @@ b	attr1
 9413	9412
 drop table test.t1, t2;
 drop database mysqltest;
+drop database if exists ndbtest1;
+create database ndbtest1;
+use ndbtest1;
+create table t1(id int) engine=ndbcluster;
+drop database ndbtest1;
+drop database ndbtest1;
+ERROR HY000: Can't drop database 'ndbtest1'; database doesn't exist
 use test;
 create table t1 (a int primary key, b char(0));
 insert into t1 values (1,"");

mysql-test/t/ndb_basic.test

@@ -360,6 +360,21 @@ select b,test.t1.attr1 from test.t1, t2 where test.t1.pk1 < a;
 drop table test.t1, t2;
 drop database mysqltest;
 
+#
+# BUG#6031 - DROP DATABASE doesn't drop database on first try
+#
+
+--disable_warnings
+drop database if exists ndbtest1;
+--enable_warnings
+
+create database ndbtest1;
+use ndbtest1;
+create table t1(id int) engine=ndbcluster;
+drop database ndbtest1;
+--error 1008
+drop database ndbtest1;
+
 #
 # test support of char(0)
 #

sql/ha_ndbcluster.cc

@@ -2777,7 +2777,7 @@ int ha_ndbcluster::reset()
 
 
 const char **ha_ndbcluster::bas_ext() const
-{ static const char *ext[]= { ".ndb", NullS }; return ext; }
+{ static const char *ext[]= { ha_ndb_ext, NullS }; return ext; }
 
 
 /*

sql/handler.cc

@@ -109,6 +109,8 @@ const char *tx_isolation_names[] =
 TYPELIB tx_isolation_typelib= {array_elements(tx_isolation_names)-1,"",
 			       tx_isolation_names, NULL};
 
+static TYPELIB known_extensions= {0,"known_exts", NULL, NULL};
+
 enum db_type ha_resolve_by_name(const char *name, uint namelen)
 {
   THD *thd=current_thd;
@@ -1633,3 +1635,57 @@ int handler::index_read_idx(byte * buf, uint index, const byte * key,
   return error;
 }
 
+/*
+  Returns a list of all known extensions.
+
+  SYNOPSIS
+    ha_known_exts()
+ 
+  NOTES
+    No mutexes, worst case race is a minor surplus memory allocation
+
+  RETURN VALUE
+    pointer		pointer to TYPELIB structure
+*/
+TYPELIB *ha_known_exts(void)
+{
+  if (!known_extensions.type_names)
+  {
+    show_table_type_st *types;
+    List<char> found_exts;
+    List_iterator_fast<char> it(found_exts);
+    const char *e, **ext;
+    
+    found_exts.push_back(".db");
+    for (types= sys_table_types; types->type; types++)
+    {      
+      if (*types->value == SHOW_OPTION_YES)
+      {
+	handler *file= get_new_handler(0,(enum db_type) types->db_type);
+	for (ext= file->bas_ext(); *ext; ext++)
+	{
+	  while (e=it++) 
+	    if (e == *ext)
+	      break;
+
+	  if (!e)
+	    found_exts.push_back((char *)*ext);
+
+	  it.rewind();
+	}
+	delete file;
+      }
+    }
+    ext= (const char **)my_once_alloc(sizeof(char *)*
+		  (found_exts.elements+1), MYF(MY_WME));
+    
+    DBUG_ASSERT(ext);
+    for (uint i=0; e=it++; i++)
+      ext[i]= e;
+    ext[found_exts.elements]= 0;
+    
+    known_extensions.count= found_exts.elements;
+    known_extensions.type_names= ext;
+  }
+  return &known_extensions;
+}

sql/handler.h

@@ -567,5 +567,5 @@ int ha_discover(THD* thd, const char* dbname, const char* name,
 int ha_find_files(THD *thd,const char *db,const char *path,
 		  const char *wild, bool dir,List<char>* files);
 int ha_table_exists(THD* thd, const char* db, const char* name);
-
+TYPELIB *ha_known_exts(void);
 

sql/sql_db.cc

@@ -30,11 +30,6 @@ const char *del_exts[]= {".frm", ".BAK", ".TMD",".opt", NullS};
 static TYPELIB deletable_extentions=
 {array_elements(del_exts)-1,"del_exts", del_exts, NULL};
 
-const char *known_exts[]=
-{".ISM",".ISD",".ISM",".MRG",".MYI",".MYD",".db", ".ibd", NullS};
-static TYPELIB known_extentions=
-{array_elements(known_exts)-1,"known_exts", known_exts, NULL};
-
 static long mysql_rm_known_files(THD *thd, MY_DIR *dirp,
 				 const char *db, const char *path,
 				 uint level);
@@ -737,7 +732,7 @@ static long mysql_rm_known_files(THD *thd, MY_DIR *dirp, const char *db,
     extension= fn_ext(file->name);
     if (find_type(extension, &deletable_extentions,1+2) <= 0)
     {
-      if (find_type(extension, &known_extentions,1+2) <= 0)
+      if (find_type(extension, ha_known_exts(),1+2) <= 0)
 	found_other_files++;
       continue;
     }