Document different config scenarios of full text search configuration.

[Baptiste Mispelon]

The documentation for full text search [1] explains that you can pass a config parameter to both SearchVector and SearchQuery but it's not clear to me if you need to pass the same configuration to both or what happens if you pass two different configurations to each object.

In other words, is there a difference between the following 3 scenarios:

# from the documentation
Entry.objects.annotate(
...     search=SearchVector('body_text', config='french'),
... ).filter(search=SearchQuery('œuf', config='french'))

Entry.objects.annotate(
...     search=SearchVector('body_text', config='french'),
... ).filter(search=SearchQuery('œuf'))

Entry.objects.annotate(
...     search=SearchVector('body_text'),
... ).filter(search=SearchQuery('œuf', config='french'))

And also, what happens when you try different configurations in the same query:

Entry.objects.annotate(
...     search=SearchVector('body_text', config='english'),
... ).filter(search=SearchQuery('œuf', config='french'))

[1] ​https://docs.djangoproject.com/en/3.0/ref/contrib/postgres/search/#changing-the-search-configuration

[Mariusz Felisiak]

Baptiste, thanks for this ticket, however it's an extensive topic and IMO ​the current explanation is sufficient for Django documentation. You should use PostgreSQL's docs for more complicated scenarios e.g. using different configs.