Buffer engine initial commit

src/infi/clickhouse_orm/engines.py

@@ -62,3 +62,30 @@ class SummingMergeTree(MergeTree):
             params.append('(%s)' % ', '.join(self.summing_cols))
         return params
 
+
+class Buffer(Engine):
+    """Here we define Buffer engine
+    Read more here https://clickhouse.yandex/reference_en.html#Buffer
+    """
+    
+    #Buffer(database, table, num_layers, min_time, max_time, min_rows, max_rows, min_bytes, max_bytes)
+    def __init__(self, table, num_layers=16, min_time=10, max_time=100, min_rows=10000, max_rows=1000000, min_bytes=10000000, max_bytes=100000000):
+        self.table = table
+        self.num_layers = num_layers
+        self.min_time = min_time
+        self.max_time = max_time
+        self.min_rows = min_rows
+        self.max_rows = max_rows
+        self.min_bytes = min_bytes
+        self.max_bytes = max_bytes
+
+
+    def create_table_sql(self, db_name, target):
+        # Overriden create_table_sql example: 
+        #sql = 'ENGINE = Buffer(merge, hits, 16, 10, 100, 10000, 1000000, 10000000, 100000000)'
+        sql = 'ENGINE = Buffer(%s, %s, %d, %d, %d, %d, %d, %d, %d)' % (
+                   db_name, target.table_name(), self.num_layers,
+                   self.min_time, self.max_time, self.min_rows,
+                   self.max_rows, self.min_bytes, self.max_bytes
+              )
+        return sql

src/infi/clickhouse_orm/models.py

@@ -156,3 +156,18 @@ class Model(with_metaclass(ModelBase)):
         '''
         data = self.__dict__
         return '\t'.join(field.to_db_string(data[name], quote=False) for name, field in self._fields)
+
+
+class BufferModel(Model):
+
+    main_model = None # table's Model should be defined in implementation. It's a table where data will be flushed
+
+    @classmethod
+    def create_table_sql(cls, db_name):
+        '''
+        Returns the SQL command for creating a table for this model.
+        '''
+        parts = ['CREATE TABLE IF NOT EXISTS `%s`.`%s` AS `%s`.`%s`' % (db_name, cls.table_name(), db_name, cls.main_model.table_name())]
+        engine_str = cls.engine.create_table_sql(db_name, cls)
+        parts.append(engine_str)
+        return ' '.join(parts)