Against a clean seeded DB, reduces `GET /post/1/` from 63 queries to
26 by removing redundancies and slow lazy-loaded queries during
top comment pagination.
Also applies eager loading to /viewmore/ with the expected reduction
from 5*(N comments) queries to ~12/request.
For testing locally, use a newly seeded DB to ensure
Comment.descendant_count is populated.
Ref: #485
Ported in logic from upstream to use SQLAlchemy eager loading instead
of repeated queries when building a submission_listing. Adjusted
loaded relationships to include only those used on TheMotte.
Using test data from seed_db, before and after:
GET /
|----------|--------|--------|--------|--------|--------|------------|
| Database | SELECT | INSERT | UPDATE | DELETE | Totals | Duplicates |
|----------|--------|--------|--------|--------|--------|------------|
| default | 83 | 0 | 0 | 0 | 83 | 72 |
|----------|--------|--------|--------|--------|--------|------------|
Total queries: 83 in 0.031s
GET /
|----------|--------|--------|--------|--------|--------|------------|
| Database | SELECT | INSERT | UPDATE | DELETE | Totals | Duplicates |
|----------|--------|--------|--------|--------|--------|------------|
| default | 14 | 0 | 0 | 0 | 14 | 0 |
|----------|--------|--------|--------|--------|--------|------------|
Total queries: 14 in 0.00718s
Generally standardizes the get_* helpers:
- Adds type hinting.
- Deduplicates block property addition.
- Respects `graceful` in more contexts.
- More resilient to invalid user input / less boilerplate necessary
at call-sites.
Borrows code from the upstream which has been working in production
reliably for ~months. Also, most of it was literally copy-pasted,
and the casted ID values aren't used later in the route functions.
