Change Summary

Change consumer DB rows fetching pattern from:

for item in items:
  existing = await db.get(item)
  if not existing:
    existing = await.db.create(item)

To:

existing_list = await db.get_bulk(items)
for item in items:
  if item not in existing_list:
    await db.create(item)

This is done in new DatabaseSaver class which replaces save_to_db function.

Before - 760RPS, 10.04% on save_to_db() + 5.28% on SQLAlchemy query cache = 15.32% of al traces.

After - 860RPS, 3.51% on DatabaseSaver.save() + 1.02% on SQLAlchemy query cache = 3.53% of all traces.

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.