Keep me

Author: nik9000

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/Length.java

@@ -100,6 +100,9 @@ public ExpressionEvaluator.Factory toEvaluator(ToEvaluator toEvaluator) {
     @Override
     public PushedBlockLoaderExpression tryPushToFieldLoading(SearchStats stats) {
         if (field instanceof FieldAttribute f) {
+            if (stats.hasDocValues(f.fieldName()) == false) {
+                return null;
+            }
             BlockLoaderWarnings warnings = new BlockLoaderWarnings(DriverContext.WarningsMode.COLLECT, source());
             return new PushedBlockLoaderExpression(f, new BlockLoaderFunctionConfig.Named("LENGTH", warnings));
         }