On Wed, May 26, 2021, at 3:07 AM, niuji...@gmail.com <mailto:niuji...%40gmail.com> wrote: > I have consistently receiving the warning: > will not produce a cache key because the ``cache_ok`` flag is not set to > True. Set this flag to True if this type object's state is safe to use in a > cache key, or False to disable this warning. > > > After reading the documentation, I learned that the "cache_ok" class-level > attribute can be set to either True or False. But the documentation is very > abstract on when to use it? What is cache key? Is it for loading and caching > a set of objects from the database? Or caching the query itself?
the caching system is used to cache the generated SQL and related parameter and result-handling structures for a statement object and is described at: https://docs.sqlalchemy.org/en/14/core/connections.html#sql-compilation-caching it is always safe to set cache_ok=False on your TypeDecorator class, you will however lose the benefit of SQL statement caching for statements which include use of this datatype. > > If my TypeDecorator class doesn't even have a __init__method, just > "process_bind_param" and "process_result_value" two methods, do I even need > to bother with this "cache_ok" setting at all? If your TypeDecorator is stateless, then it's fine to set cache_ok=True. > > -- > 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/abe578f0-fd11-468f-857d-dee6fd77ebc5n%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/abe578f0-fd11-468f-857d-dee6fd77ebc5n%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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/f3640072-8d16-4f59-bc67-f468c78878cb%40www.fastmail.com.
