feat(cells): add unique constraint to projectkeymapping table

[lynnagara]

(project_key_id, cell_name) must be unique, we should enforce it at the db level

[github-actions]

This PR has a migration; here is the generated SQL for src/sentry/migrations/1050_projectkeymapping_uniq_constraint.py

for 1050_projectkeymapping_uniq_constraint in sentry

--
-- Alter field project_key_id on projectkeymapping
--
DROP INDEX CONCURRENTLY IF EXISTS "sentry_projectkeymapping_project_key_id_fee1d050";
--
-- Create constraint sentry_projectkeymapping_project_key_id_cell_name_uniq on model projectkeymapping
--
CREATE UNIQUE INDEX CONCURRENTLY "sentry_projectkeymapping_project_key_id_cell_name_uniq" ON "sentry_projectkeymapping" ("project_key_id", "cell_name");
ALTER TABLE "sentry_projectkeymapping" ADD CONSTRAINT "sentry_projectkeymapping_project_key_id_cell_name_uniq" UNIQUE USING INDEX "sentry_projectkeymapping_project_key_id_cell_name_uniq";

[wedamija]

If we have this unique constraint, is sentry_projkeymapping_cell_name_date_updated_id_idx useful anymore?

[markstory]

I think it is, as that index includes the truncated timestamp that we'll be using to paginate through records with. Without that index, filtering on date_trunc(date_updated) will do a table scan.

[markstory]

Unique constraint looks good to me.

[markstory]

I think it is, as that index includes the truncated timestamp that we'll be using to paginate through records with. Without that index, filtering on date_trunc(date_updated) will do a table scan.