perf(core): Add partial index on execution_entity to fix executions list CPU spike (#32116)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/generated/postgres-schema/public.execution_entity.md

@@ -48,6 +48,7 @@
 | idx_execution_entity_wait_till_status_deleted_at | CREATE INDEX idx_execution_entity_wait_till_status_deleted_at ON public.execution_entity USING btree ("waitTill", status, "deletedAt") WHERE (("waitTill" IS NOT NULL) AND ("deletedAt" IS NULL)) |
 | idx_execution_entity_stopped_at_status_deleted_at | CREATE INDEX idx_execution_entity_stopped_at_status_deleted_at ON public.execution_entity USING btree ("stoppedAt", status, "deletedAt") WHERE (("stoppedAt" IS NOT NULL) AND ("deletedAt" IS NULL)) |
 | IDX_execution_entity_deduplicationKey | CREATE UNIQUE INDEX "IDX_execution_entity_deduplicationKey" ON public.execution_entity USING btree ("deduplicationKey") WHERE ("deduplicationKey" IS NOT NULL) |
+| IDX_execution_entity_workflowId_status_id | CREATE INDEX "IDX_execution_entity_workflowId_status_id" ON public.execution_entity USING btree ("workflowId", status, id) WHERE ("deletedAt" IS NULL) |
 
 ## Relations
 

packages/@n8n/db/src/entities/execution-entity.ts

@@ -28,6 +28,9 @@ export type ExecutionDataStorageLocation = 'db' | 'fs' | 's3';
 @Index(['finished', 'id'])
 @Index(['workflowId', 'finished', 'id'])
 @Index(['workflowId', 'waitTill', 'id'])
+// Partial index (Postgres only) — supports paginated list queries filtered by
+// workflowId + status without full sequential scans. See migration 1784000000029.
+@Index(['workflowId', 'status', 'id'], { where: '"deletedAt" IS NULL' })
 export class ExecutionEntity {
 	@Generated()
 	@PrimaryColumn({ transformer: idStringifier })

packages/@n8n/db/src/migrations/postgresdb/1784000000031-AddExecutionEntityWorkflowStatusIndex.ts

@@ -0,0 +1,39 @@
+import type { MigrationContext, ReversibleMigration } from '../migration-types';
+
+/**
+ * Adds a partial composite index on execution_entity(workflowId, status, id DESC)
+ * filtered to non-deleted rows (deletedAt IS NULL).
+ *
+ * Without this index Postgres performs a parallel sequential scan of the full
+ * execution_entity table for every paginated executions-list request, because
+ * the CASE-based ORDER BY and the access-control IN/EXISTS subquery prevent the
+ * planner from using any narrower path.
+ *
+ * With this index the planner can do per-workflowId range scans (one index seek
+ * per accessible workflow) and merge them into the top-N result without touching
+ * irrelevant rows, dropping the query from a full-table sequential scan to a
+ * bounded index walk.
+ *
+ * Partial (WHERE deletedAt IS NULL) keeps the index small: pruned executions are
+ * excluded and never appear in list queries.
+ *
+ * Postgres-only migration: partial functional indexes are a Postgres feature;
+ * SQLite is not affected by this performance class of issue at n8n scale.
+ */
+export class AddExecutionEntityWorkflowStatusIndex1784000000031 implements ReversibleMigration {
+	async up({ schemaBuilder: { createIndex }, escape }: MigrationContext) {
+		const col = (c: string) => escape.columnName(c);
+
+		await createIndex(
+			'execution_entity',
+			['workflowId', 'status', 'id'],
+			false,
+			undefined,
+			`${col('deletedAt')} IS NULL`,
+		);
+	}
+
+	async down({ schemaBuilder: { dropIndex } }: MigrationContext) {
+		await dropIndex('execution_entity', ['workflowId', 'status', 'id'], { skipIfMissing: true });
+	}
+}

packages/@n8n/db/src/migrations/postgresdb/index.ts

@@ -52,6 +52,7 @@ import { ChangeWorkflowStatisticsFKToNoAction1767018516000 } from './17670185160
 import { ExpandVariablesValueColumnToText1777420800000 } from './1777420800000-ExpandVariablesValueColumnToText';
 import { LimitWorkflowVersionTriggerToContent1784000000003 } from './1784000000003-LimitWorkflowVersionTriggerToContent';
 import { AddProjectIdToInstanceAiThread1784000000028 } from './1784000000028-AddProjectIdToInstanceAiThread';
+import { AddExecutionEntityWorkflowStatusIndex1784000000031 } from './1784000000031-AddExecutionEntityWorkflowStatusIndex';
 import { CreateLdapEntities1674509946020 } from '../common/1674509946020-CreateLdapEntities';
 import { PurgeInvalidWorkflowConnections1675940580449 } from '../common/1675940580449-PurgeInvalidWorkflowConnections';
 import { RemoveResetPasswordColumns1690000000030 } from '../common/1690000000030-RemoveResetPasswordColumns';
@@ -415,4 +416,5 @@ export const postgresMigrations: Migration[] = [
 	AddProjectIdToInstanceAiThread1784000000028,
 	AddJsonSizeBytesAndWorkflowVersionIdToExecutionEntity1784000000029,
 	CreateAgentChatSubscriptions1784000000030,
+	AddExecutionEntityWorkflowStatusIndex1784000000031,
 ];