Drop redundant single-column indexes shadowed by unique constraints

Removes five `Index(fields=["x"])` declarations whose columns are
already covered by a same-column `UniqueConstraint`. The unique-backed
btree handles the same lookups and enforces uniqueness, so the extra
non-unique index was pure write-side overhead with no read benefit.

- plainjobs_jobrequest: drop uuid_idx (covered by *_unique_uuid)
- plainjobs_jobprocess: drop uuid_idx (covered by *_unique_uuid)
- plainjobs_jobresult: drop uuid_idx and job_process_uuid_idx
- plainobserver_trace: drop trace_id_idx (covered by observer_unique_trace_id)

Surfaced by the upgraded `postgres.duplicate_indexes` check.

Author: davegaeddert

plain-jobs/plain/jobs/models.py

@@ -113,7 +113,6 @@ class JobRequest(postgres.Model):
             postgres.Index(
                 name="plainjobs_jobrequest_trace_id_idx", fields=["trace_id"]
             ),
-            postgres.Index(name="plainjobs_jobrequest_uuid_idx", fields=["uuid"]),
             # Used for job grouping queries
             postgres.Index(
                 name="job_request_concurrency_key",
@@ -231,7 +230,6 @@ class JobProcess(postgres.Model):
             postgres.Index(
                 name="plainjobs_jobprocess_trace_id_idx", fields=["trace_id"]
             ),
-            postgres.Index(name="plainjobs_jobprocess_uuid_idx", fields=["uuid"]),
             postgres.Index(
                 name="plainjobs_jobprocess_worker_id_idx", fields=["worker_id"]
             ),
@@ -648,10 +646,6 @@ class JobResult(postgres.Model):
             postgres.Index(
                 name="plainjobs_jobresult_created_at_idx", fields=["created_at"]
             ),
-            postgres.Index(
-                name="plainjobs_jobresult_job_process_uuid_idx",
-                fields=["job_process_uuid"],
-            ),
             postgres.Index(
                 name="plainjobs_jobresult_started_at_idx", fields=["started_at"]
             ),
@@ -670,7 +664,6 @@ class JobResult(postgres.Model):
             postgres.Index(
                 name="plainjobs_jobresult_trace_id_idx", fields=["trace_id"]
             ),
-            postgres.Index(name="plainjobs_jobresult_uuid_idx", fields=["uuid"]),
         ],
         constraints=[
             postgres.UniqueConstraint(

plain-observer/plain/observer/models.py

@@ -79,9 +79,6 @@ class Trace(postgres.Model):
             )
         ],
         indexes=[
-            postgres.Index(
-                name="plainobserver_trace_trace_id_idx", fields=["trace_id"]
-            ),
             postgres.Index(
                 name="plainobserver_trace_start_time_idx", fields=["start_time"]
             ),