python-3.xcachingsqlalchemydrop

How can clear the cache in using table.drop(engine, checkfirst=True)?

List all tables in database sample:

from sqlalchemy import (MetaData, Table)
from sqlalchemy import create_engine, inspect
db_pass = 'xxxxxx'
db_ip='127.0.0.1'
engine = create_engine('postgresql://postgres:{}@{}/sample'.format(db_pass,db_ip))
inspector = inspect(engine)
print(inspector.get_table_names())
['pre', 'sample']

Now drop the table pre:

metadata = MetaData()
pre_table = Table('pre', metadata)
pre_table.drop(engine, checkfirst=True)

Type \d when to enter into psql, only one table shown in sample database:

psql -U postgres
postgres=# \c  sample
You are now connected to database "sample" as user "postgres".
sample=# \d
public | sample                       | table    | postgres

The table pre already dropped! But print(inspector.get_table_names()) (type the second time) still shows two tables in the database:

print(inspector.get_table_names())
['pre', 'sample']

How can clear the cache in using table.drop(engine, checkfirst=True)?

Solution

  • Have you tried the inspector.clear_cache() method?

    inspector object is backed by the PGInspector class which inherits from reflection.Inspector. And the later implements this clear_cache() method.

    Disclaimer: I haven't tested this. I don't have PostgresSQL setup for it. Please comment if this works.