[fix](mysql protocol)Set more stmt exists flag correctly when forward to master.

fe/fe-core/src/main/java/org/apache/doris/qe/ConnectProcessor.java

@@ -348,6 +348,15 @@ public void executeQuery(String originStmt) throws Exception {
                 executor.getProfile().getSummaryProfile().setParseSqlStartTime(parseSqlStartTime);
                 executor.getProfile().getSummaryProfile().setParseSqlFinishTime(parseSqlFinishTime);
                 executor.getProfile().getSummaryProfile().parsedByConnectionProcess = true;
+                // Here we set the MoreStmtExists flag without considering CLIENT_MULTI_STATEMENTS.
+                // So the master will always set SERVER_MORE_RESULTS_EXISTS when the statement is not the last one.
+                // When the Follower/Observer received the return result of Master, the Follower/Observer
+                // will check CLIENT_MULTI_STATEMENTS is set or not. It sends SERVER_MORE_RESULTS_EXISTS back to client
+                // only when CLIENT_MULTI_STATEMENTS is set.
+                // See the code below : if (getConnectContext().getMysqlChannel().clientMultiStatements())
+                if (i != stmts.size() - 1 && connectType.equals(ConnectType.MYSQL)) {
+                    executor.setMoreStmtExists(true);
+                }
                 ctx.setExecutor(executor);
 
                 if (cacheKeyType != null) {
@@ -706,6 +715,9 @@ public TMasterOpResult proxyExecute(TMasterOpRequest request) throws TException
             result.setQueryId(ctx.queryId());
         }
         result.setMaxJournalId(Env.getCurrentEnv().getMaxJournalId());
+        if (request.moreResultExists) {
+            ctx.getState().serverStatus |= MysqlServerStatusFlag.SERVER_MORE_RESULTS_EXISTS;
+        }
         result.setPacket(getResultPacket());
         result.setStatus(ctx.getState().toString());
         if (ctx.getState().getStateType() == MysqlStateType.OK) {

fe/fe-core/src/main/java/org/apache/doris/qe/FEOpExecutor.java

@@ -63,6 +63,7 @@ public class FEOpExecutor {
     protected int thriftTimeoutMs;
 
     protected boolean shouldNotRetry;
+    protected boolean moreStmtExists = false;
 
     public FEOpExecutor(TNetworkAddress feAddress, OriginStatement originStmt, ConnectContext ctx, boolean isQuery) {
         this.feAddr = feAddress;
@@ -173,6 +174,7 @@ protected TMasterOpRequest buildStmtForwardParams() throws AnalysisException {
         params.setStmtId(ctx.getStmtId());
         params.setCurrentUserIdent(ctx.getCurrentUserIdentity().toThrift());
         params.setSessionId(ctx.getSessionId());
+        params.setMoreResultExists(moreStmtExists);
 
         if (Config.isCloudMode()) {
             String cluster = "";
@@ -224,6 +226,9 @@ public String getErrMsg() {
         return result.getErrMessage();
     }
 
+    public void setMoreStmtExists(boolean moreStmtExists) {
+        this.moreStmtExists = moreStmtExists;
+    }
 
     public ByteBuffer getOutputPacket() {
         if (result == null) {

fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java

@@ -201,6 +201,9 @@ public class StmtExecutor {
     private Boolean isForwardedToMaster = null;
     // Flag for execute prepare statement, need to use binary protocol resultset
     private boolean isComStmtExecute = false;
+    // Set to true if there are more stmt need to execute.
+    // Mainly for forward to master, so that master can set the mysql server status correctly.
+    private boolean moreStmtExists = false;
 
     // The result schema if "dry_run_query" is true.
     // Only one column to indicate the real return row numbers.
@@ -354,6 +357,14 @@ public boolean isForwardToMaster() {
         return isForwardedToMaster;
     }
 
+    public boolean isMoreStmtExists() {
+        return moreStmtExists;
+    }
+
+    public void setMoreStmtExists(boolean moreStmtExists) {
+        this.moreStmtExists = moreStmtExists;
+    }
+
     private boolean shouldForwardToMaster() {
         if (Env.getCurrentEnv().isMaster()) {
             return false;
@@ -945,6 +956,7 @@ private void forwardToMaster() throws Exception {
         if (LOG.isDebugEnabled()) {
             LOG.debug("need to transfer to Master. stmt: {}", context.getStmtId());
         }
+        masterOpExecutor.setMoreStmtExists(moreStmtExists);
         masterOpExecutor.execute();
         if (parsedStmt instanceof LogicalPlanAdapter) {
             // for nereids command

gensrc/thrift/FrontendService.thrift

@@ -383,6 +383,7 @@ struct TMasterOpRequest {
     29: optional TTxnLoadInfo txnLoadInfo
     30: optional TGroupCommitInfo groupCommitInfo
     31: optional binary prepareExecuteBuffer
+    32: optional bool moreResultExists // Server has more result to send
 
     // selectdb cloud
     1000: optional string cloud_cluster

regression-test/suites/query_p0/test_multiple_stmt.groovy

@@ -0,0 +1,38 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("test_multiple_stmt") {
+    sql """drop database if exists test_multiple_stmt"""
+    sql """create database test_multiple_stmt"""
+    sql """use test_multiple_stmt"""
+    sql """CREATE TABLE test_multiple_stmt (
+            key1 int NOT NULL,
+            value1 int NOT NULL,
+        )ENGINE=OLAP
+        DUPLICATE KEY(`key1`)
+        COMMENT "OLAP"
+        DISTRIBUTED BY HASH(`key1`) BUCKETS 2
+        PROPERTIES (
+            "replication_num" = "1"
+        )
+    """
+
+    def result = sql """insert into test_multiple_stmt values (1, 1); select * from test_multiple_stmt;"""
+    assertEquals(1, result.size())
+    assertEquals(1, result[0][0])
+    assertEquals(1, result[0][1])
+}