ndb_insert.test, ndb_insert.result, ha_ndbcluster.cc:

  Bug#27980 INSERT IGNORE wrongly ignores NULLs in unique index: added check for null values

mysql-test/r/ndb_insert.result

@@ -649,3 +649,11 @@ pk	a
 6	NULL
 7	4
 DROP TABLE t1;
+create table t1(a int primary key, b int, unique key(b)) engine=ndb;
+insert ignore into t1 values (1,0), (2,0), (2,null), (3,null);
+select * from t1 order by a;
+a	b
+1	0
+2	NULL
+3	NULL
+drop table t1;

mysql-test/t/ndb_insert.test

@@ -630,4 +630,13 @@ INSERT IGNORE INTO t1 VALUES (4,NULL),(5,NULL),(6,NULL),(7,4);
 SELECT * FROM t1 ORDER BY pk;
 DROP TABLE t1;
 
+#
+# Bug #27980  	INSERT IGNORE wrongly ignores NULLs in unique index
+#
+
+create table t1(a int primary key, b int, unique key(b)) engine=ndb;
+insert ignore into t1 values (1,0), (2,0), (2,null), (3,null);
+select * from t1 order by a;
+drop table t1;
+
 # End of 4.1 tests

sql/ha_ndbcluster.cc

@@ -1630,6 +1630,34 @@ bool ha_ndbcluster::check_all_operations_for_error(NdbTransaction *trans,
   DBUG_RETURN(true);
 }
 
+
+/**
+ * Check if record contains any null valued columns that are part of a key
+ */
+static
+int
+check_null_in_record(const KEY* key_info, const byte *record)
+{
+  KEY_PART_INFO *curr_part, *end_part;
+  curr_part= key_info->key_part;
+  end_part= curr_part + key_info->key_parts;
+
+  while (curr_part != end_part)
+  {
+    if (curr_part->null_bit &&
+        (record[curr_part->null_offset] & curr_part->null_bit))
+      return 1;
+    curr_part++;
+  }
+  return 0;
+  /*
+    We could instead pre-compute a bitmask in table_share with one bit for
+    every null-bit in the key, and so check this just by OR'ing the bitmask
+    with the null bitmap in the record.
+    But not sure it's worth it.
+  */
+}
+
 /*
  * Peek to check if any rows already exist with conflicting
  * primary key or unique index values
@@ -1671,7 +1699,17 @@ int ha_ndbcluster::peek_indexed_rows(const byte *record, bool check_pk)
     if (i != table->s->primary_key &&
         key_info->flags & HA_NOSAME)
     {
-      // A unique index is defined on table
+      /*
+        A unique index is defined on table.
+        We cannot look up a NULL field value in a unique index. But since
+        keys with NULLs are not indexed, such rows cannot conflict anyway, so
+        we just skip the index in this case.
+      */
+      if (check_null_in_record(key_info, record))
+      {
+	DBUG_PRINT("info", ("skipping check for key with NULL"));
+        continue;
+      } 
       NdbIndexOperation *iop;
       NDBINDEX *unique_index = (NDBINDEX *) m_index[i].unique_index;
       key_part= key_info->key_part;
@@ -2816,7 +2854,7 @@ int ha_ndbcluster::index_end()
 }
 
 /**
- * Check if key contains null
+ * Check if key contains nullable columns
  */
 static
 int