Allow wildcards in CACHALOT_UNCACHABLE_TABLES

[jacobjove]

Description

It would be nice to be able to use wildcards (*) in the CACHALOT_UNCACHABLE_TABLES setting; e.g.,

CACHALOT_UNCACHABLE_TABLES = frozenset(
    (
        'django_migrations',
        'myapp_*',
    )

Rationale

In the case that all models in a particular app must be excluded from Cachalot, this is very convenient.

Alternatives?

//: # Add another setting like CACHALOT_UNCACHABLE_APPS

[Andrew-Chen-Wang]

Thanks for the suggestion @iacobfred ! I like the alternative better as that makes sure we keep performance on par. I believe I can get all models associated with an app on initial Django setup and add that to CACHALOT_UNCACHABLE_TABLES, but that means cachalot must be placed after all others apps, right? If anything, I love the CACHALOT_UNCACHABLE_APPS idea. (Note to self: probably adding CACHALOT_CACHABLE_APPS is logical).

My initial analysis of the original suggestion

My only concern would be performance / implementation of this wildcard. I've identified the most prominent areas in which it's used:

django-cachalot/cachalot/utils.py

Lines 158 to 177 in 1569ff7

	def is_cachable(table):
	whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
	if whitelist and table not in whitelist:
	return False
	return table not in cachalot_settings.CACHALOT_UNCACHABLE_TABLES
	def are_all_cachable(tables):
	whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
	if whitelist and not tables.issubset(whitelist):
	return False
	return tables.isdisjoint(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
	def filter_cachable(tables):
	whitelist = cachalot_settings.CACHALOT_ONLY_CACHABLE_TABLES
	tables = tables.difference(cachalot_settings.CACHALOT_UNCACHABLE_TABLES)
	if whitelist:
	return tables.intersection(whitelist)
	return tables

We use sets a lot, and a wildcard would add a severe amount of Python rather than the C impl and when you think about ORMs (and from internals, these methods are called a lot), this adds a huge overhead.

[Andrew-Chen-Wang]

@iacobfred please let me know if #187 fixes this!

[jacobjove]

@iacobfred please let me know if #187 fixes this!

@Andrew-Chen-Wang, yes it does! Thanks!

[Andrew-Chen-Wang]

I'm still going to see if I can implement this in the quest to deploy Django with partitioned tables... ref #153 (btw I won't comment on here anymore to not annoy with notifications, but leaving it open for reference later on).