fix(db): index large-value workflow_id FKs so workflow deletes don't seq-scan (#6136)

packages/db/migrations/0278_charming_imperial_guard.sql

@@ -0,0 +1,14 @@
+-- Both tables carry `workflow_id ... ON DELETE SET NULL` (migration 0212) with no index leading
+-- on that column. Postgres implements SET NULL as an AFTER ROW referential trigger running
+-- `UPDATE ... SET workflow_id = NULL WHERE workflow_id = $1` once per deleted parent row, so
+-- every `DELETE FROM workflow` sequentially scans both tables per workflow — enough to blow the
+-- statement timeout once the soft-delete retention job starts hard-deleting archived workflows.
+-- Both indexes exist to make that trigger index-driven.
+--
+-- Replay-safety: this file is only CONCURRENTLY index builds below an embedded COMMIT, so a
+-- failure replays the whole file — both statements are idempotent.
+COMMIT;--> statement-breakpoint
+SET lock_timeout = 0;--> statement-breakpoint
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "execution_large_value_references_workflow_id_idx" ON "execution_large_value_references" USING btree ("workflow_id");--> statement-breakpoint
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "execution_large_values_workflow_id_idx" ON "execution_large_values" USING btree ("workflow_id");--> statement-breakpoint
+SET lock_timeout = '5s';

packages/db/migrations/meta/_journal.json

@@ -1940,6 +1940,13 @@
       "when": 1785358812851,
       "tag": "0277_workspace_sandboxes",
       "breakpoints": true
+    },
+    {
+      "idx": 278,
+      "version": "7",
+      "when": 1785536864363,
+      "tag": "0278_charming_imperial_guard",
+      "breakpoints": true
     }
   ]
 }

packages/db/schema.ts

@@ -501,6 +501,12 @@ export const executionLargeValues = pgTable(
     tombstoneCleanupIdx: index('execution_large_values_tombstone_cleanup_idx')
       .on(table.workspaceId, table.deletedAt, table.key)
       .where(sql`${table.deletedAt} IS NOT NULL`),
+    /**
+     * Backs the `ON DELETE SET NULL` referential trigger, which runs
+     * `UPDATE ... WHERE workflow_id = $1` once per deleted workflow row and
+     * would otherwise sequentially scan this table each time.
+     */
+    workflowIdIdx: index('execution_large_values_workflow_id_idx').on(table.workflowId),
   })
 )
 
@@ -521,6 +527,8 @@ export const executionLargeValueReferences = pgTable(
     workspaceExecutionSourceIdx: index(
       'execution_large_value_references_workspace_execution_source_idx'
     ).on(table.workspaceId, table.executionId, table.source),
+    /** Backs the `ON DELETE SET NULL` referential trigger — see `executionLargeValues`. */
+    workflowIdIdx: index('execution_large_value_references_workflow_id_idx').on(table.workflowId),
   })
 )