feat(core): Node hints improvements (no-changelog) (#9387)

Co-authored-by: Giulio Andreini <andreini@netseven.it>

packages/nodes-base/nodes/Postgres/v2/actions/router.ts

@@ -1,5 +1,5 @@
 import type { IExecuteFunctions, INodeExecutionData } from 'n8n-workflow';
-import { NodeOperationError } from 'n8n-workflow';
+import { NodeExecutionOutput, NodeOperationError } from 'n8n-workflow';
 
 import { configurePostgres } from '../transport';
 import { configureQueryRunner } from '../helpers/utils';
@@ -17,7 +17,8 @@ export async function router(this: IExecuteFunctions): Promise<INodeExecutionDat
 
 	const credentials = (await this.getCredentials('postgres')) as PostgresNodeCredentials;
 	const options = this.getNodeParameter('options', 0, {}) as PostgresNodeOptions;
-	options.nodeVersion = this.getNode().typeVersion;
+	const node = this.getNode();
+	options.nodeVersion = node.typeVersion;
 	options.operation = operation;
 
 	const { db, pgp, sshClient } = await configurePostgres(credentials, options);
@@ -62,5 +63,17 @@ export async function router(this: IExecuteFunctions): Promise<INodeExecutionDat
 		if (!db.$pool.ending) await db.$pool.end();
 	}
 
+	if (operation === 'select' && items.length > 1 && !node.executeOnce) {
+		return new NodeExecutionOutput(
+			[returnData],
+			[
+				{
+					message: `This node ran ${items.length} times, once for each input item. To run for the first item only, enable 'execute once' in the node settings`,
+					location: 'outputPane',
+				},
+			],
+		);
+	}
+
 	return [returnData];
 }