When using MariaDB v10.5+ Foreign-Key errors were popping up because of
some changes in that version. To mitigate this on MariaDB and other
MySQL forks those errors are now catched, and instead of a replace_into
an update will happen. I have tested this as thorough as possible with
MariaDB 10.5, 10.4, 10.3 and the default MySQL on Ubuntu Focal. And
tested it again using sqlite, all seems to be ok on all tables.
resolves#1081. resolves#1065, resolves#1050
Diesel requires the following changes:
- Separate connection and pool types per connection, the generate_connections! macro generates an enum with a variant per db type
- Separate migrations and schemas, these were always imported as one type depending on db feature, now they are all imported under different module names
- Separate model objects per connection, the db_object! macro generates one object for each connection with the diesel macros, a generic object, and methods to convert between the connection-specific and the generic ones
- Separate connection queries, the db_run! macro allows writing only one that gets compiled for all databases or multiple ones
