added local cache

app.py

@@ -68,24 +68,32 @@ USER = os.getenv('DATABASE_USER')
 PASSWORD = os.getenv('DATABASE_PASSWORD')
 # load sql
 
-
 def load_sql_data(query):
     if SQL_KEY in CACHE:
         return CACHE[SQL_KEY]
-    conn = psycopg2.connect(
-        host=HOST,
-        database=DATABASE,
-        user=USER,
-        password=PASSWORD
-    )
-    df = pd.read_sql_query(query, conn)
-    df = df.drop(['item_doi'], axis=1)
-
-    # Close the database connection
-    conn.close()
-    CACHE[SQL_KEY] = df
-    return df
-
+    try:
+        conn = psycopg2.connect(
+            host=HOST,
+            database=DATABASE,
+            user=USER,
+            password=PASSWORD
+        )
+        df = pd.read_sql_query(query, conn)
+        df = df.drop(['item_doi'], axis=1)
+
+        # Close the database connection
+        conn.close()
+
+        CACHE[SQL_KEY] = df
+        return df
+
+    except psycopg2.Error:
+        # If there is an error connecting to the database, load data from the compressed CSV file
+        df = pd.read_csv('compressed_data.bz2', compression='bz2')
+        df = df.drop(['item_doi'], axis=1)
+        
+        CACHE[SQL_KEY] = df
+        return df
 
 # main_df
 main_df = load_sql_data(query)