SQLAlchemy: How do you delete multiple rows without querying
Question:
I have a table that has millions of rows. I want to delete multiple rows via an in clause. However, using the code:
session.query(Users).filter(Users.id.in_(subquery....)).delete()
The above code will query the results, and then execute the delete. I don’t want to do that. I want speed.
I want to be able to execute (yes I know about the session.execute):Delete from users where id in ()
So the Question: How can I get the best of two worlds, using the ORM? Can I do the delete without hard coding the query?
Answers:
Yep! You can call delete() on the table object with an associated where clause.
Something like this:
stmt = Users.__table__.delete().where(Users.id.in_(subquery...))
(and then don’t forget to execute the statement: engine.execute(stmt))
To complete dizzy‘s answer:
delete_q = Report.__table__.delete().where(Report.data == 'test')
db.session.execute(delete_q)
db.session.commit()
The below solution also works, if developers do not want to execute a plain vanilla query.
session.query(Users).filter(Users.id.in_(subquery....)).delete(synchronize_session=False)
New syntax (1.4 version and above)
from sqlalchemy import delete
statement = delete(User).where(User.id.in_(...))
session.exec(statement) # sync syntax
# session.execute(statement) # async syntax
https://docs.sqlalchemy.org/en/14/core/dml.html?highlight=delete
I have a table that has millions of rows. I want to delete multiple rows via an in clause. However, using the code:
session.query(Users).filter(Users.id.in_(subquery....)).delete()
The above code will query the results, and then execute the delete. I don’t want to do that. I want speed.
I want to be able to execute (yes I know about the session.execute):Delete from users where id in ()
So the Question: How can I get the best of two worlds, using the ORM? Can I do the delete without hard coding the query?
Yep! You can call delete() on the table object with an associated where clause.
Something like this:
stmt = Users.__table__.delete().where(Users.id.in_(subquery...))
(and then don’t forget to execute the statement: engine.execute(stmt))
To complete dizzy‘s answer:
delete_q = Report.__table__.delete().where(Report.data == 'test')
db.session.execute(delete_q)
db.session.commit()
The below solution also works, if developers do not want to execute a plain vanilla query.
session.query(Users).filter(Users.id.in_(subquery....)).delete(synchronize_session=False)
New syntax (1.4 version and above)
from sqlalchemy import delete
statement = delete(User).where(User.id.in_(...))
session.exec(statement) # sync syntax
# session.execute(statement) # async syntax
https://docs.sqlalchemy.org/en/14/core/dml.html?highlight=delete