merge cherry-pick-mr-7765-1751264780967-auto into 6.0.0

【回合6.0.0】修复enable_multi_charset下walsender初始化失败的问题

Created-by: chenxiaobin19
Commit-by: chenxiaobin19
Merged-by: opengauss_bot
Description: 【标题】(请简要描述下实现的内容)
【回合6.0.0】修复enable_multi_charset下walsender初始化失败的问题
【实现内容】:
见：https://gitcode.com/opengauss/openGauss-server/pull/7765
【根因分析】:

【实现方案】:

【关联需求或issue】:

【开发自验报告】:
1. 请附上自验结果(内容或者截图)
2. 是否可以添加fastcheck测试用例，如是，请补充fastcheck用例
3. 是否涉及资料修改，如是，在docs仓库补充资料
4. 是否考虑升级场景(系统表修改、日志持久化以及修改执行态数据格式)
5. 是否考虑在线扩容等扩展场景
6. 是否考虑异常场景/并发场景/前向兼容/性能场景
7. 是否对其他模块产生影响
8. 是否需要回合补丁版本(5.0、6.0)，涉及(**结果错误|coredump|性能劣化|内存泄露|集群异常**)相关修复请排查回合补丁分支

【其他说明】:

See merge request: opengauss/openGauss-server!8006

src/common/backend/utils/init/postinit.cpp

@@ -2826,6 +2826,7 @@ void PostgresInitializer::InitSettings()
 
     /* initialize client encoding */
     InitializeClientEncoding();
+    InitializeCharsetEncoding();
 }
 
 void PostgresInitializer::InitExtensionVariable()

src/common/backend/utils/mb/mbutils.cpp

@@ -241,6 +241,14 @@ void InitializeClientEncoding(void)
                     pg_enc2name_tbl[u_sess->mb_cxt.pending_client_encoding].name,
                     GetDatabaseEncodingName())));
     }
+}
+
+void InitializeCharsetEncoding(void)
+{
+    if (!u_sess->mb_cxt.backend_startup_complete) {
+        return;
+    }
+
     u_sess->mb_cxt.character_set_connection = &pg_enc2name_tbl[GetDatabaseEncoding()];
     if (ENABLE_MULTI_CHARSET) {
         u_sess->mb_cxt.collation_connection = get_default_collation_by_charset(GetDatabaseEncoding(), false);

src/include/mb/pg_wchar.h

@@ -463,6 +463,7 @@ extern mbcharacter_incrementer pg_database_encoding_character_incrementer(void);
 extern int PrepareClientEncoding(int encoding);
 extern int SetClientEncoding(int encoding);
 extern void InitializeClientEncoding(void);
+extern void InitializeCharsetEncoding(void);
 extern int pg_get_client_encoding(void);
 extern const char* pg_get_client_encoding_name(void);
 

src/test/regress/input/charset_connection_test.source

@@ -177,4 +177,16 @@ select * from t1;
 create database latin1_db dbcompatibility 'b' encoding 'latin1' lc_ctype = 'C' lc_collate = 'C';
 \c latin1_db
 select '高斯aa' = '高斯AA';
+
+\! @abs_bindir@/gs_guc reload -Z datanode -D @abs_srcdir@/tmp_check/datanode1 -c "b_format_behavior_compat_options='enable_multi_charset'" >/dev/null 2>&1
+select pg_sleep(1);
+
+\! mkdir @abs_srcdir@/tmp_check/charset_connection_test_backup/
+\! @abs_bindir@/gs_basebackup -hlocalhost -p@portstring@ -D @abs_srcdir@/tmp_check/charset_connection_test_backup/ 2>&1 |grep successfully
+
+\! rm -rf @abs_srcdir@/tmp_check/charset_connection_test_backup/
+
+\! @abs_bindir@/gs_guc reload -Z datanode -D @abs_srcdir@/tmp_check/datanode1 -c "b_format_behavior_compat_options=''" >/dev/null 2>&1
+select pg_sleep(1);
+
 \c regression

src/test/regress/output/charset_connection_test.source

@@ -587,4 +587,22 @@ select '高斯aa' = '高斯AA';
  f
 (1 row)
 
+\! @abs_bindir@/gs_guc reload -Z datanode -D @abs_srcdir@/tmp_check/datanode1 -c "b_format_behavior_compat_options='enable_multi_charset'" >/dev/null 2>&1
+select pg_sleep(1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
+\! mkdir @abs_srcdir@/tmp_check/charset_connection_test_backup/
+\! @abs_bindir@/gs_basebackup -hlocalhost -p@portstring@ -D @abs_srcdir@/tmp_check/charset_connection_test_backup/ 2>&1 |grep successfully
+--?.*gs_basebackup: base backup successfully
+\! rm -rf @abs_srcdir@/tmp_check/charset_connection_test_backup/
+\! @abs_bindir@/gs_guc reload -Z datanode -D @abs_srcdir@/tmp_check/datanode1 -c "b_format_behavior_compat_options=''" >/dev/null 2>&1
+select pg_sleep(1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
 \c regression