fix so that ndb handler can cope with char(0), mapped to char(1) for now

mysql-test/r/ndb_basic.result

@@ -395,3 +395,22 @@ b	attr1
 9413	9412
 drop table test.t1, t2;
 drop database mysqltest;
+use test;
+create table t1 (a int primary key, b char(0));
+insert into t1 values (1,"");
+insert into t1 values (2,NULL);
+select * from t1 order by a;
+a	b
+1	
+2	NULL
+select * from t1 order by b;
+a	b
+2	NULL
+1	
+select * from t1 where b IS NULL;
+a	b
+2	NULL
+select * from t1 where b IS NOT NULL;
+a	b
+1	
+drop table t1;

mysql-test/t/ndb_basic.test

@@ -358,3 +358,16 @@ select b,test.t1.attr1 from test.t1, t2 where test.t1.pk1 < a;
 drop table test.t1, t2;
 drop database mysqltest;
 
+#
+# test support of char(0)
+#
+
+use test;
+create table t1 (a int primary key, b char(0));
+insert into t1 values (1,"");
+insert into t1 values (2,NULL);
+select * from t1 order by a;
+select * from t1 order by b;
+select * from t1 where b IS NULL;
+select * from t1 where b IS NOT NULL;
+drop table t1;

sql/ha_ndbcluster.cc

@@ -89,6 +89,12 @@ static int ndb_get_table_statistics(Ndb*, const char *,
 				    Uint64* rows, Uint64* commits);
 
 
+/*
+  Dummy buffer to read zero pack_length fields
+  which are mapped to 1 char
+*/
+static byte dummy_buf[1];
+
 /*
   Error handling functions
 */
@@ -443,6 +449,13 @@ int ha_ndbcluster::set_ndb_value(NdbOperation *ndb_op, Field *field,
 
   if (ndb_supported_type(field->type()))
   {
+    // ndb currently does not support size 0
+    const byte *empty_field= "";
+    if (pack_len == 0)
+    {
+      pack_len= 1;
+      field_ptr= empty_field;
+    }
     if (! (field->flags & BLOB_FLAG))
     {
       if (field->is_null())
@@ -586,7 +599,11 @@ int ha_ndbcluster::get_ndb_value(NdbOperation *ndb_op, Field *field,
       DBUG_ASSERT(field->ptr != NULL);
       if (! (field->flags & BLOB_FLAG))
       {	
-	byte *field_buf= buf + (field->ptr - table->record[0]);
+	byte *field_buf;
+	if (field->pack_length() != 0)
+	  field_buf= buf + (field->ptr - table->record[0]);
+	else
+	  field_buf= dummy_buf;
         m_value[fieldnr].rec= ndb_op->getValue(fieldnr, 
 					       field_buf);
         DBUG_RETURN(m_value[fieldnr].rec == NULL);
@@ -3164,7 +3181,10 @@ static int create_ndb_column(NDBCOL &col,
       col.setType(NDBCOL::Char);
       col.setCharset(cs);
     }
-    col.setLength(field->pack_length());
+    if (field->pack_length() == 0)
+      col.setLength(1); // currently ndb does not support size 0
+    else
+      col.setLength(field->pack_length());
     break;
   case MYSQL_TYPE_VAR_STRING:
     if (field->flags & BINARY_FLAG)