Improved TaskRun environment indexes (#2164)

### PR: Optimize **TaskRun** indexes for hot-path queries

**What changed**

| Object                          | Type                                                            | Purpose                                                                                                    |
| ------------------------------- | --------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------- |
| `taskrun_runtime_id_desc_idx`   | **BTREE** `(runtimeEnvironmentId, id DESC) INCLUDE (createdAt)` | Eliminates explicit sort for the “latest task runs” query (`ORDER BY id DESC`) while remaining index-only. |
| `taskrun_runtime_createdat_idx` | **BTREE** `(runtimeEnvironmentId, createdAt DESC) INCLUDE (id)` | Accelerates the filter-only path that scans by `createdAt >= …` without any ordering requirement.          |
| `taskrun_createdat_brin`        | **BRIN** on `createdAt` (`pages_per_range = 128`)               | Lets the planner skip whole blocks older than the time window for both queries at < 100 MB cost.           |
| *(cleanup)*                     | **DROP** `TaskRun_runtimeEnvironmentId_createdAt_id_idx`        | Retires the 3-column index once the new ones are built.                                                    |

**Key details**

* All indexes created **CONCURRENTLY** to avoid write blocking.
* `fillfactor = 90` on b-trees for balanced space vs. future growth.
* Net disk usage drops **≈ 15–20 GB** while each query now gets a purpose-built access path.

**Why**

* Remove planner Sort nodes for the top-N “latest runs” view.
* Speed up environment-filtered range scans.
* Shrink index bloat and improve cache efficiency.

Author: ericallam

internal-packages/database/prisma/migrations/20250611075637_remove_task_run_environment_created_at_id_index/migration.sql

@@ -0,0 +1 @@
+DROP INDEX CONCURRENTLY IF EXISTS "TaskRun_runtimeEnvironmentId_createdAt_id_idx";

internal-packages/database/prisma/migrations/20250611080026_add_task_run_environment_id_index_including_created_at/migration.sql

@@ -0,0 +1 @@
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "TaskRun_runtimeEnvironmentId_id_idx" ON "TaskRun"("runtimeEnvironmentId", "id" DESC) INCLUDE ("createdAt") WITH (fillfactor = 90);

internal-packages/database/prisma/migrations/20250611080322_add_task_run_environment_created_at_index_including_id/migration.sql

@@ -0,0 +1 @@
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "TaskRun_runtimeEnvironmentId_createdAt_idx" ON "TaskRun"("runtimeEnvironmentId", "createdAt" DESC) INCLUDE ("id") WITH (fillfactor = 90);

internal-packages/database/prisma/migrations/20250611080537_add_task_run_created_at_brin_index/migration.sql

@@ -0,0 +1 @@
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "TaskRun_createdAt_idx" ON "TaskRun" USING BRIN ("createdAt");

internal-packages/database/prisma/schema.prisma

@@ -680,9 +680,12 @@ model TaskRun {
   // Schedule list page
   @@index([scheduleId, createdAt(sort: Desc)])
   // Finding runs in a batch
-  @@index([runtimeEnvironmentId, batchId])
-  @@index([runtimeEnvironmentId, createdAt(sort: Desc), id(sort: Desc)])
   @@index([runTags(ops: ArrayOps)], type: Gin)
+  @@index([runtimeEnvironmentId, batchId])
+  // This will include the createdAt index to help speed up the run list page
+  @@index([runtimeEnvironmentId, id(sort: Desc)])
+  @@index([runtimeEnvironmentId, createdAt(sort: Desc)])
+  @@index([createdAt], type: Brin)
 }
 
 enum TaskRunStatus {