- Add materialized views for list -> subscriber counts, dashboard chart,
and dashboard aggregate stats that slow down significantly on large
databases (with millions or tens of millions of subscribers). These
slow queries involve full table scan COUNTS().
- Add a toggle to enable caching slow results in Settings -> Performance.
- Add support for setting a cron string that crons and periodically
refreshes aggregated stats in materialized views.
Closes#1019.
This commit adds a new API `POST /api/tx` that sends an ad-hoc message
to a subscriber based on a pre-defined transactional template. This is
a large commit that adds the following:
- New campaign / tx template types on the UI. tx templates have an
additional subject field.
- New fields `type` and `subject` to the templates table.
- Refactor template CRUD operations and models.
- Refactor template func assignment in manager.
- Add pre-compiled template caching to manager runtime.
- Pre-compile all tx templates into memory on program boot to avoid
expensive template compilation on ad-hoc tx messages.
