MDEV-33145 support for old-mode=OLD_FLUSH_STATUS

add old-mode that restores inconsistent legacy behavior for FLUSH STATUS.
It doesn't affect FLUSH { SESSION | GLOBAL } STATUS.

include/mysql_com.h

@@ -194,8 +194,7 @@ enum enum_indicator_type
 #define REFRESH_LOG             (1ULL << 1)  /* Start on new log file */
 #define REFRESH_TABLES          (1ULL << 2)  /* close all tables */
 #define REFRESH_HOSTS           (1ULL << 3)  /* Flush host cache */
-#define REFRESH_SESSION_STATUS  (1ULL << 4)  /* Flush status variables */
-#define REFRESH_STATUS REFRESH_SESSION_STATUS
+#define REFRESH_STATUS          (1ULL << 4)  /* Flush status variables */
 #define REFRESH_THREADS         (1ULL << 5)  /* Flush thread cache */
 #define REFRESH_SLAVE           (1ULL << 6)  /* Reset master info and restart
                                                 slave thread */
@@ -220,6 +219,7 @@ enum enum_indicator_type
 #define REFRESH_FOR_EXPORT      (1ULL << 20) /* FLUSH TABLES ... FOR EXPORT */
 #define REFRESH_SSL             (1ULL << 21)
 #define REFRESH_GLOBAL_STATUS   (1ULL << 22)  /* Flush global status */
+#define REFRESH_SESSION_STATUS  (1ULL << 23)  /* Flush session status */
 
 #define REFRESH_GENERIC         (1ULL << 30)
 #define REFRESH_FAST            (1ULL << 31) /* Intern flag */

mysql-test/main/mysqld--help.result

@@ -739,8 +739,8 @@ The following specify which files/extra groups are read (specified before remain
  NO_DUP_KEY_WARNINGS_WITH_IGNORE, NO_PROGRESS_INFO, 
  ZERO_DATE_TIME_CAST, UTF8_IS_UTF8MB3, 
  IGNORE_INDEX_ONLY_FOR_JOIN, COMPAT_5_1_CHECKSUM, 
- NO_NULL_COLLATION_IDS, LOCK_ALTER_TABLE_COPY, or ALL to
- set all combinations
+ NO_NULL_COLLATION_IDS, LOCK_ALTER_TABLE_COPY, 
+ OLD_FLUSH_STATUS, or ALL to set all combinations
  --old-passwords     Use old password encryption method (needed for 4.0 and
  older clients)
  --old-style-user-limits 

mysql-test/main/status.result

@@ -488,4 +488,29 @@ select $new_local_flush_status  >= $local_flush_status as "1";
 select $new_global_flush_status < $new_local_flush_status as "1";
 1
 1
+create or replace table t1 (a int, key(a)) engine=MyISAM;
+insert into t1 values (1),(2);
+connect con1,localhost,root;
+set old_mode=OLD_FLUSH_STATUS;
+Warnings:
+Warning	1287	'OLD_FLUSH_STATUS' is deprecated and will be removed in a future release
+insert into t1 values (3),(4);
+drop table t1;
+select t1.variable_name, t1.variable_value as global_value, t2.variable_value as session_value
+from information_schema.global_status t1 join information_schema.session_status t2
+on t1.variable_name = t2.variable_name
+where t1.variable_name in ('Key_writes','Com_insert');
+variable_name	global_value	session_value
+COM_INSERT	2	1
+KEY_WRITES	2	2
+flush status;
+select t1.variable_name, t1.variable_value as global_value, t2.variable_value as session_value
+from information_schema.global_status t1 join information_schema.session_status t2
+on t1.variable_name = t2.variable_name
+where t1.variable_name in ('Key_writes','Com_insert');
+variable_name	global_value	session_value
+COM_INSERT	2	0
+KEY_WRITES	0	0
+disconnect con1;
+connection default;
 # end of 11.5 tests

mysql-test/main/status.test

@@ -506,4 +506,32 @@ let $new_local_flush_status= `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.SESS
 --evalp select $new_local_flush_status  >= $local_flush_status as "1"
 --evalp select $new_global_flush_status < $new_local_flush_status as "1"
 
+#
+# Test OLD_FLUSH_STATUS
+#
+
+create or replace table t1 (a int, key(a)) engine=MyISAM;
+insert into t1 values (1),(2);
+
+--connect con1,localhost,root
+set old_mode=OLD_FLUSH_STATUS;
+
+insert into t1 values (3),(4);
+drop table t1;
+
+select t1.variable_name, t1.variable_value as global_value, t2.variable_value as session_value
+from information_schema.global_status t1 join information_schema.session_status t2
+ on t1.variable_name = t2.variable_name
+where t1.variable_name in ('Key_writes','Com_insert');
+
+flush status;
+
+select t1.variable_name, t1.variable_value as global_value, t2.variable_value as session_value
+from information_schema.global_status t1 join information_schema.session_status t2
+ on t1.variable_name = t2.variable_name
+where t1.variable_name in ('Key_writes','Com_insert');
+
+disconnect con1;
+connection default;
+
 --echo # end of 11.5 tests

mysql-test/suite/sys_vars/r/old_mode_basic.result

@@ -132,8 +132,8 @@ Warning	1287	'ZERO_DATE_TIME_CAST' is deprecated and will be removed in a future
 SELECT @@global.old_mode;
 @@global.old_mode
 ZERO_DATE_TIME_CAST
-SET @@global.old_mode = 256;
-ERROR 42000: Variable 'old_mode' can't be set to the value of '256'
+SET @@global.old_mode = 6536;
+ERROR 42000: Variable 'old_mode' can't be set to the value of '6536'
 SELECT @@global.old_mode;
 @@global.old_mode
 ZERO_DATE_TIME_CAST

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -2329,7 +2329,7 @@ VARIABLE_COMMENT	Used to emulate old behavior from earlier MariaDB or MySQL vers
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM,NO_NULL_COLLATION_IDS,LOCK_ALTER_TABLE_COPY
+ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM,NO_NULL_COLLATION_IDS,LOCK_ALTER_TABLE_COPY,OLD_FLUSH_STATUS
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	OLD_PASSWORDS

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -2539,7 +2539,7 @@ VARIABLE_COMMENT	Used to emulate old behavior from earlier MariaDB or MySQL vers
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM,NO_NULL_COLLATION_IDS,LOCK_ALTER_TABLE_COPY
+ENUM_VALUE_LIST	NO_DUP_KEY_WARNINGS_WITH_IGNORE,NO_PROGRESS_INFO,ZERO_DATE_TIME_CAST,UTF8_IS_UTF8MB3,IGNORE_INDEX_ONLY_FOR_JOIN,COMPAT_5_1_CHECKSUM,NO_NULL_COLLATION_IDS,LOCK_ALTER_TABLE_COPY,OLD_FLUSH_STATUS
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	OLD_PASSWORDS

mysql-test/suite/sys_vars/t/old_mode_basic.test

@@ -172,7 +172,7 @@ SET @@global.old_mode = 4;
 SELECT @@global.old_mode;
 
 --Error ER_WRONG_VALUE_FOR_VAR
-SET @@global.old_mode = 256;
+SET @@global.old_mode = 6536;
 SELECT @@global.old_mode;
 
 # use of decimal values

sql/mysqld.cc

@@ -9227,6 +9227,52 @@ void refresh_global_status()
   max_used_connections_time= time(nullptr);
 }
 
+/** Emulate the legacy FLUSH STATUS inconsistent behavior
+
+  * additive session variables are added to global and set to 0 in session
+  * non-additive global variables are set to 0
+*/
+void refresh_status_legacy(THD *thd)
+{
+  mysql_mutex_lock(&LOCK_status);
+
+#ifdef WITH_PERFSCHEMA_STORAGE_ENGINE
+  /* Reset aggregated status counters. */
+  reset_pfs_status_stats();
+#endif
+
+  /* Add thread's status variabes to global status */
+  add_to_status(&global_status_var, &thd->status_var);
+
+  /* Reset thread's status variables */
+  thd->set_status_var_init();
+  thd->status_var.global_memory_used= 0;
+  bzero((uchar*) &thd->org_status_var, sizeof(thd->org_status_var));
+  thd->start_bytes_received= 0;
+
+  /* Reset some global variables */
+  reset_status_vars();
+#ifdef WITH_WSREP
+  if (WSREP_ON)
+  {
+    Wsrep_server_state::instance().provider().reset_status();
+  }
+#endif /* WITH_WSREP */
+
+  /* Reset the counters of all key caches (default and named). */
+  process_key_caches(reset_key_cache_counters, 0);
+  global_status_var.flush_status_time= my_time(0);
+  mysql_mutex_unlock(&LOCK_status);
+
+  /*
+    Set max_used_connections to the number of currently open
+    connections.  This is not perfect, but status data is not exact anyway.
+  */
+  max_used_connections= connection_count + extra_connection_count;
+  max_used_connections_time= time(nullptr);
+}
+
+
 
 #ifdef HAVE_PSI_INTERFACE
 static PSI_file_info all_server_files[]=

sql/mysqld.h

@@ -80,6 +80,7 @@ void close_connection(THD *thd, uint sql_errno= 0);
 void handle_connection_in_main_thread(CONNECT *thd);
 void create_thread_to_handle_connection(CONNECT *connect);
 void unlink_thd(THD *thd);
+void refresh_status_legacy(THD *thd);
 void refresh_session_status(THD *thd);
 void refresh_global_status();
 bool is_secure_file_path(char *path);

sql/sql_class.h

@@ -207,6 +207,7 @@ enum enum_binlog_row_image {
 #define OLD_MODE_COMPAT_5_1_CHECKSUM    (1 << 5)
 #define OLD_MODE_NO_NULL_COLLATION_IDS  (1 << 6)
 #define OLD_MODE_LOCK_ALTER_TABLE_COPY  (1 << 7)
+#define OLD_MODE_OLD_FLUSH_STATUS       (1 << 8)
 
 #define OLD_MODE_DEFAULT_VALUE          OLD_MODE_UTF8_IS_UTF8MB3
 

sql/sql_parse.cc

@@ -2183,6 +2183,9 @@ dispatch_command_return dispatch_command(enum enum_server_command command, THD *
     if (trans_commit_implicit(thd))
       break;
     thd->release_transactional_locks();
+    if (options & REFRESH_STATUS &&
+        !(thd->variables.old_behavior & OLD_MODE_OLD_FLUSH_STATUS))
+      options= (options & ~REFRESH_STATUS) | REFRESH_SESSION_STATUS;
     if ((options & ~REFRESH_SESSION_STATUS) &&
         check_global_access(thd,RELOAD_ACL))
       break;
@@ -5277,6 +5280,7 @@ mysql_execute_command(THD *thd, bool is_called_from_prepared_stmt)
 #ifdef HAVE_QUERY_CACHE
     REFRESH_QUERY_CACHE_FREE                |
 #endif /* HAVE_QUERY_CACHE */
+    REFRESH_STATUS                          |
     REFRESH_SESSION_STATUS                  |
     REFRESH_GLOBAL_STATUS                   |
     REFRESH_USER_RESOURCES))

sql/sql_reload.cc

@@ -379,6 +379,8 @@ bool reload_acl_and_cache(THD *thd, unsigned long long options,
 #endif
   if (options & REFRESH_HOSTS)
     hostname_cache_refresh();
+  if (thd && (options & REFRESH_STATUS))
+    refresh_status_legacy(thd);
   if (thd && (options & REFRESH_SESSION_STATUS))
     refresh_session_status(thd);
   if ((options & REFRESH_GLOBAL_STATUS))

sql/sql_yacc.yy

@@ -14673,7 +14673,12 @@ flush_option:
             Lex->relay_log_connection_name= empty_clex_str;
           }
         | STATUS_SYM
-          { Lex->type|= REFRESH_SESSION_STATUS; }
+          {
+            if (thd->variables.old_behavior & OLD_MODE_OLD_FLUSH_STATUS)
+              Lex->type|= REFRESH_STATUS;
+            else
+              Lex->type|= REFRESH_SESSION_STATUS;
+          }
         | SESSION_SYM STATUS_SYM
           { Lex->type|= REFRESH_SESSION_STATUS; }
         | GLOBAL_SYM STATUS_SYM

sql/sys_vars.cc

@@ -3955,6 +3955,7 @@ static const char *old_mode_names[]=
   "COMPAT_5_1_CHECKSUM",                // 5: deprecated since 11.3
   "NO_NULL_COLLATION_IDS",              // 6: deprecated since 11.3
   "LOCK_ALTER_TABLE_COPY",              // 7: deprecated since 11.3
+  "OLD_FLUSH_STATUS",                   // 8: deprecated since 11.5
   0
 };
 
@@ -3974,6 +3975,9 @@ static bool old_mode_deprecated(sys_var *self, THD *thd, set_var *var)
   for (; i <= 7; i++)
     if ((1ULL<<i) & v)
       warn_deprecated<1103>(thd, old_mode_names[i]);
+  for (; i <= 8; i++)
+    if ((1ULL<<i) & v)
+      warn_deprecated<1105>(thd, old_mode_names[i]);
   return false;
 }