Bug #28405 please add a Com_change_user status variable
Submitted: 13 May 2007 18:50 Modified: 14 May 2007 9:39
Reporter: Shane Bester (Platinum Quality Contributor) Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: General Severity:S4 (Feature request)
Version:5.0, 5.1, 5.5 OS:Any
Assigned to: Geir H√łydalsvik
Tags: Com_change_user, mysql_change_user
Triage: Triaged: D5 (Feature request)

[13 May 2007 18:50] Shane Bester
Description:
It would be nice to have a status variable to display the number of times C api function mysql_change_user was called.

How to repeat:
<?php
        $db=mysqli_connect("127.0.0.1","root","") or die("can't connect");
        mysqli_select_db($db,"test") or die("can't change db");
        for($i=0;$i<1000;$i++)
        {
                mysqli_change_user($db,"root","","test") or die("error: ".mysqli_error($db));
        }
        mysqli_close($db);
?>

now try to determine how many calls are made to mysql_change_user() by viewing status variables on server.

Suggested fix:
.
[14 May 2007 9:39] Valerii Kravchuk
Thank you for a reasonable feature request.
[3 Mar 2010 5:08] Shane Bester
related: bug #51667 (Need status variable for com_ping)
[3 Mar 2010 11:03] Mark Leith
I have extended the patch from Bug#51667 to include this as well. Based on the mysql-next-mr tree:

=== modified file 'sql/mysqld.cc'
--- sql/mysqld.cc       revid:alik@sun.com-20100114090008-3rsdmlp1w2mqgrhg
+++ sql/mysqld.cc       2010-03-03 09:57:40 +0000
@@ -3131,6 +3131,7 @@
   {"call_procedure",       (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_CALL]), SHOW_LONG_STATUS},
   {"change_db",            (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_CHANGE_DB]), SHOW_LONG_STATUS},
   {"change_master",        (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_CHANGE_MASTER]), SHOW_LONG_STATUS},
+  {"change_user",          (char*) offsetof(STATUS_VAR, com_change_user), SHOW_LONG_STATUS},
   {"check",                (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_CHECK]), SHOW_LONG_STATUS},
   {"checksum",             (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_CHECKSUM]), SHOW_LONG_STATUS},
   {"commit",               (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_COMMIT]), SHOW_LONG_STATUS},
@@ -3174,6 +3175,7 @@
   {"load",                 (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_LOAD]), SHOW_LONG_STATUS},
   {"lock_tables",          (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_LOCK_TABLES]), SHOW_LONG_STATUS},
   {"optimize",             (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_OPTIMIZE]), SHOW_LONG_STATUS},
+  {"ping",                 (char*) offsetof(STATUS_VAR, com_ping), SHOW_LONG_STATUS},
   {"preload_keys",         (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_PRELOAD_KEYS]), SHOW_LONG_STATUS},
   {"prepare_sql",          (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_PREPARE]), SHOW_LONG_STATUS},
   {"purge",                (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_PURGE]), SHOW_LONG_STATUS},
@@ -3350,11 +3352,13 @@
     We have few debug-only commands in com_status_vars, only visible in debug
     builds. for simplicity we enable the assert only in debug builds
 
-    There are 8 Com_ variables which don't have corresponding SQLCOM_ values:
+    There are 10 Com_ variables which don't have corresponding SQLCOM_ values:
     (TODO strictly speaking they shouldn't be here, should not have Com_ prefix
     that is. Perhaps Stmt_ ? Comstmt_ ? Prepstmt_ ?)
 
       Com_admin_commands       => com_other
+      Com_change_user          => com_change_user
+      Com_ping                 => com_ping
       Com_stmt_close           => com_stmt_close
       Com_stmt_execute         => com_stmt_execute
       Com_stmt_fetch           => com_stmt_fetch
@@ -3368,7 +3372,7 @@
     of SQLCOM_ constants.
   */
   compile_time_assert(sizeof(com_status_vars)/sizeof(com_status_vars[0]) - 1 ==
-                     SQLCOM_END + 8);
+                     SQLCOM_END + 10);
 #endif
 
   if (get_options(&remaining_argc, &remaining_argv))

=== modified file 'sql/sql_class.h'
--- sql/sql_class.h     revid:alik@sun.com-20100114090008-3rsdmlp1w2mqgrhg
+++ sql/sql_class.h     2010-03-03 09:56:18 +0000
@@ -443,6 +443,8 @@
   ulong ha_discover_count;
   ulong ha_savepoint_count;
   ulong ha_savepoint_rollback_count;
+  ulong com_ping;
+  ulong com_change_user;
 
   /* KEY_CACHE parts. These are copies of the original */
   ulong key_blocks_changed;

=== modified file 'sql/sql_parse.cc'
--- sql/sql_parse.cc    revid:alik@sun.com-20100114090008-3rsdmlp1w2mqgrhg
+++ sql/sql_parse.cc    2010-03-03 09:56:19 +0000
@@ -979,7 +979,7 @@
 #endif
   case COM_CHANGE_USER:
   {
-    status_var_increment(thd->status_var.com_other);
+    status_var_increment(thd->status_var.com_change_user);
     char *user= (char*) packet, *packet_end= packet + packet_length;
     /* Safe because there is always a trailing \0 at the end of the packet */
     char *passwd= strend(user)+1;
@@ -1409,7 +1409,7 @@
     break;
   }
   case COM_PING:
-    status_var_increment(thd->status_var.com_other);
+    status_var_increment(thd->status_var.com_ping);
     my_ok(thd);                                // Tell client we are alive
     break;
   case COM_PROCESS_INFO: