On Fri, Mar 5, 2021 at 8:34 AM Mike Bayer <mike...@zzzcomputing.com> wrote:
> yeah in fact that engine.begin() here is using a brand new SQLite > connection each time as the default pool for SQlite files is NullPool, as > it is a very fast connecting database and it is the safest option for > concurrency. So in your first example, you have a brand new file > connection and all of your WAL setup code is running each tme. In the > second example, it runs only once. > > background on pooling: > > > https://docs.sqlalchemy.org/en/13/dialects/sqlite.html#threading-pooling-behavior > > if you use the SingletonThreadPool instead of the default NullPool, you > will again get the same performance with engine.begin(). however, there is > no need to change existing code that uses engine.connect() / > connection.begin(). > Got it, thanks. I had read https://docs.sqlalchemy.org/en/13/core/pooling.html#connection-pool-configuration but managed to miss the fine print that SingletonThreadPool was used for in-memory connections and NullPool was used for file connection. -- Jonathan Brandmeyer -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/CA%2BXzfkoPwxu0EdHTHWK1Ya8xEMJ8NUdDnf%3DBNVxeBG8vLOsOJA%40mail.gmail.com.
