diff --git a/ml-algorithms/src/main/java/org/opensearch/ml/engine/algorithms/remote/RemoteConnectorExecutor.java b/ml-algorithms/src/main/java/org/opensearch/ml/engine/algorithms/remote/RemoteConnectorExecutor.java
index c8af4935a7..e6fa6331bc 100644
--- a/ml-algorithms/src/main/java/org/opensearch/ml/engine/algorithms/remote/RemoteConnectorExecutor.java
+++ b/ml-algorithms/src/main/java/org/opensearch/ml/engine/algorithms/remote/RemoteConnectorExecutor.java
@@ -11,6 +11,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicReference;
@@ -27,6 +28,8 @@
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.ml.common.FunctionName;
 import org.opensearch.ml.common.connector.Connector;
+import org.opensearch.ml.common.connector.ConnectorAction;
+import org.opensearch.ml.common.connector.MLPreProcessFunction;
 import org.opensearch.ml.common.dataset.MLInputDataset;
 import org.opensearch.ml.common.dataset.TextDocsInputDataSet;
 import org.opensearch.ml.common.dataset.remote.RemoteInferenceInputDataSet;
@@ -99,6 +102,15 @@ private Tuple<Integer, Integer> calculateChunkSize(TextDocsInputDataSet textDocs
                 return Tuple.tuple(textDocsLength / stepSize + 1, stepSize);
             }
         } else {
+            Optional<ConnectorAction> predictAction = getConnector().findPredictAction();
+            if (predictAction.isEmpty()) {
+                throw new IllegalArgumentException("no predict action found");
+            }
+            String preProcessFunction = predictAction.get().getPreProcessFunction();
+            if (preProcessFunction != null && !MLPreProcessFunction.contains(preProcessFunction)) {
+                // user defined preprocess script, this case, the chunk size is always equals to text docs length.
+                return Tuple.tuple(textDocsLength, 1);
+            }
             // consider as batch.
             return Tuple.tuple(1, textDocsLength);
         }
diff --git a/ml-algorithms/src/test/java/org/opensearch/ml/engine/algorithms/remote/AwsConnectorExecutorTest.java b/ml-algorithms/src/test/java/org/opensearch/ml/engine/algorithms/remote/AwsConnectorExecutorTest.java
index 5e1a9dfacb..13b2ceb987 100644
--- a/ml-algorithms/src/test/java/org/opensearch/ml/engine/algorithms/remote/AwsConnectorExecutorTest.java
+++ b/ml-algorithms/src/test/java/org/opensearch/ml/engine/algorithms/remote/AwsConnectorExecutorTest.java
@@ -6,6 +6,7 @@
 package org.opensearch.ml.engine.algorithms.remote;
 
 import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.when;
@@ -30,6 +31,7 @@
 import org.opensearch.common.settings.Settings;
 import org.opensearch.common.util.concurrent.ThreadContext;
 import org.opensearch.core.action.ActionListener;
+import org.opensearch.ingest.TestTemplateService;
 import org.opensearch.ml.common.FunctionName;
 import org.opensearch.ml.common.connector.AwsConnector;
 import org.opensearch.ml.common.connector.Connector;
@@ -42,6 +44,7 @@
 import org.opensearch.ml.common.transport.MLTaskResponse;
 import org.opensearch.ml.engine.encryptor.Encryptor;
 import org.opensearch.ml.engine.encryptor.EncryptorImpl;
+import org.opensearch.script.ScriptService;
 import org.opensearch.threadpool.ThreadPool;
 
 import com.google.common.collect.ImmutableList;
@@ -67,10 +70,15 @@ public class AwsConnectorExecutorTest {
 
     Encryptor encryptor;
 
+    @Mock
+    private ScriptService scriptService;
+
     @Before
     public void setUp() {
         MockitoAnnotations.openMocks(this);
         encryptor = new EncryptorImpl("m+dWmfmnNRiNlOdej/QelEkvMTyH//frS2TBeS2BP4w=");
+        when(scriptService.compile(any(), any()))
+            .then(invocation -> new TestTemplateService.MockTemplateScript.Factory("{\"result\": \"hello world\"}"));
     }
 
     @Test
@@ -282,4 +290,80 @@ public void executePredict_RemoteInferenceInput_negativeStepSize_throwIllegalArg
         Mockito.verify(actionListener, times(1)).onFailure(exceptionCaptor.capture());
         assert exceptionCaptor.getValue() instanceof IllegalArgumentException;
     }
+
+    @Test
+    public void executePredict_TextDocsInferenceInput_withoutStepSize_emptyPredictionAction() {
+        ConnectorAction predictAction = ConnectorAction
+            .builder()
+            .actionType(ConnectorAction.ActionType.PREDICT)
+            .method("POST")
+            .url("http://openai.com/mock")
+            .requestBody("{\"input\": ${parameters.input}}")
+            .preProcessFunction(MLPreProcessFunction.TEXT_DOCS_TO_OPENAI_EMBEDDING_INPUT)
+            .build();
+        Map<String, String> credential = ImmutableMap
+            .of(ACCESS_KEY_FIELD, encryptor.encrypt("test_key"), SECRET_KEY_FIELD, encryptor.encrypt("test_secret_key"));
+        Map<String, String> parameters = ImmutableMap.of(REGION_FIELD, "us-west-2", SERVICE_NAME_FIELD, "sagemaker");
+        Connector connector = AwsConnector
+            .awsConnectorBuilder()
+            .name("test connector")
+            .version("1")
+            .protocol("http")
+            .parameters(parameters)
+            .credential(credential)
+            .build();
+        connector.decrypt((c) -> encryptor.decrypt(c));
+        AwsConnectorExecutor executor = spy(new AwsConnectorExecutor(connector));
+        Settings settings = Settings.builder().build();
+        threadContext = new ThreadContext(settings);
+        when(executor.getClient()).thenReturn(client);
+        when(client.threadPool()).thenReturn(threadPool);
+        when(threadPool.getThreadContext()).thenReturn(threadContext);
+
+        MLInputDataset inputDataSet = TextDocsInputDataSet.builder().docs(ImmutableList.of("input1", "input2", "input3")).build();
+        executor
+            .executePredict(MLInput.builder().algorithm(FunctionName.TEXT_EMBEDDING).inputDataset(inputDataSet).build(), actionListener);
+        ArgumentCaptor<Exception> exceptionArgumentCaptor = ArgumentCaptor.forClass(Exception.class);
+        Mockito.verify(actionListener, times(1)).onFailure(exceptionArgumentCaptor.capture());
+        assert exceptionArgumentCaptor.getValue() instanceof IllegalArgumentException;
+        assert "no predict action found".equals(exceptionArgumentCaptor.getValue().getMessage());
+    }
+
+    @Test
+    public void executePredict_TextDocsInferenceInput_withoutStepSize_userDefinedPreProcessFunction() {
+        ConnectorAction predictAction = ConnectorAction
+            .builder()
+            .actionType(ConnectorAction.ActionType.PREDICT)
+            .method("POST")
+            .url("http://openai.com/mock")
+            .requestBody("{\"input\": ${parameters.input}}")
+            .preProcessFunction(
+                "\n    StringBuilder builder = new StringBuilder();\n    builder.append(\"\\\"\");\n    String first = params.text_docs[0];\n    builder.append(first);\n    builder.append(\"\\\"\");\n    def parameters = \"{\" +\"\\\"text_inputs\\\":\" + builder + \"}\";\n    return  \"{\" +\"\\\"parameters\\\":\" + parameters + \"}\";"
+            )
+            .build();
+        Map<String, String> credential = ImmutableMap
+            .of(ACCESS_KEY_FIELD, encryptor.encrypt("test_key"), SECRET_KEY_FIELD, encryptor.encrypt("test_secret_key"));
+        Map<String, String> parameters = ImmutableMap.of(REGION_FIELD, "us-west-2", SERVICE_NAME_FIELD, "sagemaker");
+        Connector connector = AwsConnector
+            .awsConnectorBuilder()
+            .name("test connector")
+            .version("1")
+            .protocol("http")
+            .parameters(parameters)
+            .credential(credential)
+            .actions(Arrays.asList(predictAction))
+            .build();
+        connector.decrypt((c) -> encryptor.decrypt(c));
+        AwsConnectorExecutor executor = spy(new AwsConnectorExecutor(connector));
+        Settings settings = Settings.builder().build();
+        threadContext = new ThreadContext(settings);
+        when(executor.getClient()).thenReturn(client);
+        when(client.threadPool()).thenReturn(threadPool);
+        when(threadPool.getThreadContext()).thenReturn(threadContext);
+        when(executor.getScriptService()).thenReturn(scriptService);
+
+        MLInputDataset inputDataSet = TextDocsInputDataSet.builder().docs(ImmutableList.of("input1", "input2", "input3")).build();
+        executor
+            .executePredict(MLInput.builder().algorithm(FunctionName.TEXT_EMBEDDING).inputDataset(inputDataSet).build(), actionListener);
+    }
 }