optimization 1 (free ram space after loading page)

olapy/core/mdx/executor/execute_db.py

 from __future__ import absolute_import, division, print_function
 
 from sqlalchemy import inspect
-
+import pandas as pd
 from ..tools.mem_bench import memory_usage
 from ..tools.connection import MyDB
 import pandas.io.sql as psql
@@ -19,12 +19,37 @@ def _load_tables_db(executer_instance):
 
     memory_usage("1 - before executing query //// _load_tables_db")
     for table_name in inspector.get_table_names():
-        value = psql.read_sql_query(
-            'SELECT * FROM "{0}"'.format(table_name), db.engine)
+
+        # value = psql.read_sql_query(
+        #     'SELECT * FROM "{0}"'.format(table_name), db.engine)
+
+        # results = db.engine.execute('SELECT * FROM "{0}"'.format(table_name))
+        results = (db.engine
+                   .execution_options(stream_results=True)
+                   .execute('SELECT * FROM "{0}"'.format(table_name)))
+        # Fetch all the results of the query
+        fetchall = results.fetchall()
+        # fetchall = results.fetchone()
+        value = pd.DataFrame(fetchall,columns=results.keys())
 
         tables[table_name] = value[[
             col for col in value.columns if col.lower()[-3:] != '_id'
         ]]
+
+    # tables = {}
+    # db = MyDB(db_config_file_path=executer_instance.DATA_FOLDER, db=executer_instance.cube)
+    # # inspector = inspect(db.engine)
+    # cursor = db.engine.cursor()
+    # cursor.execute("""SELECT table_name FROM information_schema.tables
+    #                           WHERE table_schema = 'public'""")
+    #
+    # for table_name in cursor.fetchall():
+    #     value = psql.read_sql_query(
+    #         'SELECT * FROM "{0}" '.format(table_name[0]), db.engine)
+    #
+    #     tables[table_name[0]] = value[[
+    #         col for col in value.columns if col.lower()[-3:] != '_id'
+    #     ]]
     memory_usage("2 - after query, before fetchall  /////// _load_tables_db")
     return tables