The ?tweaks_version parameter tells Caqti drivers to enable all tweaks introduced up to and including the given major and minor version of Caqti.
Occasionally Caqti makes changes to the database session parameters or otherwise how it interacts with specific database systems. This may be done to improve consistency across databases, to make it easier to detect mistakes, to avoid obsolete behaviour, etc. However, this can break backwards compatibility with applications, sometimes in subtle ways, which is the motivation for the ?tweaks_version parameter of the connecting functions.
Passing ~tweaks_version:(major_version, minor_verson) declares that the application is compatible with all tweaks introduced up to and including that version of Caqti. The default is to omit all tweaks introduced since the last major version. On each major release, all tweaks up to that point becomes permanent and requesting an earlier tweaks version will have no effect.
Production code should either omit the parameter or pass the largest major and minor version pair for which the code has been tested. This offers the choice of adapting only on major versions or incrementally.
Code in development can declare a progressive value, like the next major version, in order to always use the latest set of tweaks.
(1, 8) and laterPRAGMA foreign_keys = ON for the session.