This removes an N+1 with taggings but doesn't solve the one with tags.
Using `includes(taggings: :base_tags)` based on
47da5036de/lib/acts_as_taggable_on/taggable.rb (L83-L84)
wasn't enough to solve it and I got to stop here. This is scope-creeping
too much.
We get from an initial INNER JOIN with variants and products to fetch
the variant overrides + N queries like:
```sql
SELECT "spree_variants".* FROM "spree_variants" WHERE
"spree_variants"."deleted_at" IS NULL AND "spree_variants"."id" = $1
LIMIT 1 [["id", 1545]]
SELECT "spree_products".* FROM "spree_products" WHERE
"spree_products"."id" = $1 LIMIT 1 [["id", 604]]
```
to the same initial INNER JOIN + just 2 queries like:
```sql
SELECT "spree_variants".* FROM "spree_variants" WHERE
"spree_variants"."deleted_at" IS NULL AND "spree_variants"."id" IN
(1551, 1554)
SELECT "spree_products".* FROM "spree_products" WHERE
"spree_products"."deleted_at" IS NULL AND "spree_products"."id" IN (606,
607)
```
In the line below we filter them out in Ruby so it's a waste of
resources. The fundamental difference is that `#includes` and
`#references` results in LEFT JOINs, whereas `#joins` results in INNER
JOIN, and because there's a default scope on `deleted_at IS NULL`, these
are not included in the result set.
This however, requires us to move away from the current algorithm but
unfortunately we can't refactor it completely yet.
Before:
```sql
SELECT *
FROM "variant_overrides"
LEFT OUTER
JOIN "spree_variants"
ON "spree_variants"."id" = "variant_overrides"."variant_id"
AND "spree_variants"."deleted_at" IS NULL
LEFT OUTER
JOIN "spree_products"
ON "spree_products"."id" = "spree_variants"."product_id"
AND "spree_products"."deleted_at" IS NULL
WHERE "variant_overrides"."permission_revoked_at" IS NULL
AND "variant_overrides"."hub_id" IN (
SELECT "enterprises"."id"
FROM "enterprises"
INNER
JOIN "enterprise_roles"
ON "enterprise_roles"."enterprise_id" = "enterprises"."id"
WHERE (enterprise_roles.user_id = ?)
AND (sells != 'none')
ORDER BY name)
```
After:
```sql
SELECT "variant_overrides".*
FROM "variant_overrides"
INNER
JOIN "spree_variants"
ON "spree_variants"."id" = "variant_overrides"."variant_id"
AND "spree_variants"."deleted_at" IS NULL
INNER
JOIN "spree_products"
ON "spree_products"."id" = "spree_variants"."product_id"
AND "spree_products"."deleted_at" IS NULL
WHERE "variant_overrides"."permission_revoked_at" IS NULL
AND "variant_overrides"."hub_id" IN (
SELECT "enterprises"."id"
FROM "enterprises"
INNER
JOIN "enterprise_roles"
ON "enterprise_roles"."enterprise_id" = "enterprises"."id"
WHERE (enterprise_roles.user_id = ?)
AND (sells != 'none')
ORDER BY name)
```
This is covered in the test suite by
spec/controllers/admin/variant_overrides_controller_spec.rb:72. It keeps
passing so we're good to go.
#update_column(s) skips callbacks (which is useful), but it doesn't change the updated_at field on the record by default (which we should be doing in these cases).
This change is made in Spree 2.2 here: b367c629ce
