From bfd634f9c79bd30511a90cb3021df4802046b96e Mon Sep 17 00:00:00 2001
From: morrySnow <101034200+morrySnow@users.noreply.github.com>
Date: Thu, 27 Jun 2024 18:35:40 +0800
Subject: [PATCH] [fix](protocol) only return multi result when
 CLIENT_MULTI_STATEMENTS been set (#36759) (#36919)

pick from master #36759

multi statement support by PR #3050.
But there is a minor issue in implementation.

as MySQL dev doc say in


https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_command_phase_sp.html#sect_protocol_command_phase_sp_multi_statement

server should only process multi statement
when client set CLIENT_MULTI_STATEMENTS.
When client not set CLIENT_MULTI_STATEMENTS, server should treat query
as single statement.

but Doris do slightly different with MySQL server. Doris always treat
query as multi statement, but only return multi result when client set
CLIENT_MULTI_STATEMENTS. When client do not set CLIENT_MULTI_STATEMENTS,
Doris will return the last statement result only.

Co-authored-by: Mingyu Chen <morningman.cmy@gmail.com>
---
 .../main/java/org/apache/doris/mysql/MysqlCapability.java | 6 +++++-
 .../main/java/org/apache/doris/qe/ConnectProcessor.java   | 8 +++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/mysql/MysqlCapability.java b/fe/fe-core/src/main/java/org/apache/doris/mysql/MysqlCapability.java
index 0701b6ac2f..b3d4793eeb 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/mysql/MysqlCapability.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/mysql/MysqlCapability.java
@@ -161,9 +161,13 @@ public class MysqlCapability {
         return (flags & Flag.CLIENT_DEPRECATE_EOF.getFlagBit()) != 0;
     }
 
+    public boolean isClientMultiStatements() {
+        return (flags & Flag.CLIENT_MULTI_STATEMENTS.getFlagBit()) != 0;
+    }
+
     @Override
     public boolean equals(Object obj) {
-        if (obj == null || !(obj instanceof MysqlCapability)) {
+        if (!(obj instanceof MysqlCapability)) {
             return false;
         }
         if (flags != ((MysqlCapability) obj).flags) {
diff --git a/fe/fe-core/src/main/java/org/apache/doris/qe/ConnectProcessor.java b/fe/fe-core/src/main/java/org/apache/doris/qe/ConnectProcessor.java
index 51911c0333..358e5d1a07 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/qe/ConnectProcessor.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/qe/ConnectProcessor.java
@@ -315,7 +315,13 @@ public abstract class ConnectProcessor {
                         if (i != stmts.size() - 1) {
                             ctx.getState().serverStatus |= MysqlServerStatusFlag.SERVER_MORE_RESULTS_EXISTS;
                             if (ctx.getState().getStateType() != MysqlStateType.ERR) {
-                                finalizeCommand();
+                                // here, doris do different with mysql.
+                                // when client not request CLIENT_MULTI_STATEMENTS, mysql treat all query as
+                                // single statement. Doris treat it with multi statement, but only return
+                                // the last statement result.
+                                if (getConnectContext().getCapability().isClientMultiStatements()) {
+                                    finalizeCommand();
+                                }
                             }
                         }
                     } else if (connectType.equals(ConnectType.ARROW_FLIGHT_SQL)) {