Unexepected null connection

[djouallah]

errors

RuntimeError                              Traceback (most recent call last)
<timed exec> in <module>

[/usr/local/lib/python3.12/dist-packages/chdb/state/sqlitelike.py](https://localhost:8080/#) in query(self, query, format)
    496             format = "Arrow"
    497 
--> 498         result = self._conn.query(query, format)
    499         return result_func(result)
    500 

RuntimeError: Unexepected null connection

source notebook
https://colab.research.google.com/drive/1sJD7w6l7RUjRHoPKoM4EQGcfwRqfKCqk?usp=sharing

[wudidapaopao]

Hi @djouallah, this error occurs because when you execute the following code block twice, the conn obtained via chdb.connect() in the first execution and the conn obtained via chdb.connect() in the second execution share the same connection. The first conn object has its connection reclaimed by Python garbage collection, which causes the internal connection of the conn obtained in the second execution to be null.
A quick way to avoid this issue is to manually release conn after using it.

import chdb
conn = chdb.connect()
conn.query("CREATE DATABASE IF NOT EXISTS db_xxx  ; use db_xxx")
for tbl in tbl_list :
    conn.query(f" CREATE OR REPLACE view {tbl}  as select * from deltaLakeLocal('{Table_Path}/CH{SF}/{tbl}') ")
df = execute_query(conn, sql)
save_results(df, 'chdb')
conn.close() # Newly added line