Bug#14236170 MYSQLDUMP 5.5.25 CLIENT FAILS TO DUMP

MYSQL DB FROM REMOTE 5.0.96 SERVER

Problem: mysqldump tool assumes the existence of
general_log and slow_log tables in the server.
If mysqldump tool executes on a old server where
there are no log tables like these, mysqldump tool
fails.

Analysis: general_log and slow_log tables are added
in the ignore-table list as part of bug-26121 fix
causes bug-45740 (MYSQLDUMP DOESN'T DUMP GENERAL_LOG
AND SLOW_QUERY CAUSES RESTORE PROBLEM). As part of
the bug-45740 fix, mysqldump tool adds create table
queries for these two tables. But the fix assumes
that on all the servers, general_log and slow_log
will be there. If the new mysqldump tool is executed
against a old server where there are no general_log
and slow_log, the mysqldump tool fails with an error
that 'there is no general_log table'.

Fix: When mysqldump tool is trying to retrieve general_log
and slow_log table structures, first the tool should
check their existence of these tables in the server
instead of trying to dump it blindly.

client/mysqldump.c

@@ -83,14 +83,6 @@
 #define IGNORE_DATA 0x01 /* don't dump data for this table */
 #define IGNORE_INSERT_DELAYED 0x02 /* table doesn't support INSERT DELAYED */
 
-/* general_log or slow_log tables under mysql database */
-static inline my_bool general_log_or_slow_log_tables(const char *db, 
-                                                     const char *table)
-{
-  return (strcmp(db, "mysql") == 0) &&
-         ((strcmp(table, "general_log") == 0) ||
-          (strcmp(table, "slow_log") == 0));
-}
 
 static void add_load_option(DYNAMIC_STRING *str, const char *option,
                              const char *option_value);
@@ -2410,6 +2402,15 @@ static uint dump_routines_for_db(char *db)
   DBUG_RETURN(0);
 }
 
+/* general_log or slow_log tables under mysql database */
+static inline my_bool general_log_or_slow_log_tables(const char *db,
+                                                     const char *table)
+{
+  return (!my_strcasecmp(charset_info, db, "mysql")) &&
+          (!my_strcasecmp(charset_info, table, "general_log") ||
+           !my_strcasecmp(charset_info, table, "slow_log"));
+}
+
 /*
   get_table_structure -- retrievs database structure, prints out corresponding
   CREATE statement and fills out insert_pat if the table is the type we will
@@ -4285,7 +4286,8 @@ static int dump_all_tables_in_db(char *database)
   char table_buff[NAME_LEN*2+3];
   char hash_key[2*NAME_LEN+2];  /* "db.tablename" */
   char *afterdot;
-  int using_mysql_db= my_strcasecmp(&my_charset_latin1, database, "mysql");
+  my_bool general_log_table_exists= 0, slow_log_table_exists=0;
+  int using_mysql_db= !my_strcasecmp(charset_info, database, "mysql");
   DBUG_ENTER("dump_all_tables_in_db");
 
   afterdot= strmov(hash_key, database);
@@ -4296,22 +4298,6 @@ static int dump_all_tables_in_db(char *database)
   if (opt_xml)
     print_xml_tag(md_result_file, "", "\n", "database", "name=", database, NullS);
 
-  if (strcmp(database, "mysql") == 0)
-  {
-    char table_type[NAME_LEN];
-    char ignore_flag;
-    uint num_fields;
-    num_fields= get_table_structure((char *) "general_log", 
-                                    database, table_type, &ignore_flag);
-    if (num_fields == 0)
-      verbose_msg("-- Warning: get_table_structure() failed with some internal "
-                  "error for 'general_log' table\n");
-    num_fields= get_table_structure((char *) "slow_log", 
-                                    database, table_type, &ignore_flag);
-    if (num_fields == 0)
-      verbose_msg("-- Warning: get_table_structure() failed with some internal "
-                  "error for 'slow_log' table\n");
-  }
   if (lock_tables)
   {
     DYNAMIC_STRING query;
@@ -4357,6 +4343,26 @@ static int dump_all_tables_in_db(char *database)
         }
       }
     }
+    else
+    {
+      /*
+        If general_log and slow_log exists in the 'mysql' database,
+         we should dump the table structure. But we cannot
+         call get_table_structure() here as 'LOCK TABLES' query got executed
+         above on the session and that 'LOCK TABLES' query does not contain
+         'general_log' and 'slow_log' tables. (you cannot acquire lock
+         on log tables). Hence mark the existence of these log tables here and
+         after 'UNLOCK TABLES' query is executed on the session, get the table
+         structure from server and dump it in the file.
+      */
+      if (using_mysql_db)
+      {
+        if (!my_strcasecmp(charset_info, table, "general_log"))
+          general_log_table_exists= 1;
+        else if (!my_strcasecmp(charset_info, table, "slow_log"))
+          slow_log_table_exists= 1;
+      }
+    }
   }
   if (opt_events && mysql_get_server_version(mysql) >= 50106)
   {
@@ -4375,7 +4381,26 @@ static int dump_all_tables_in_db(char *database)
   }
   if (lock_tables)
     (void) mysql_query_with_error_report(mysql, 0, "UNLOCK TABLES");
-  if (flush_privileges && using_mysql_db == 0)
+  if (using_mysql_db)
+  {
+    char table_type[NAME_LEN];
+    char ignore_flag;
+    if (general_log_table_exists)
+    {
+      if (!get_table_structure((char *) "general_log",
+                               database, table_type, &ignore_flag) )
+        verbose_msg("-- Warning: get_table_structure() failed with some internal "
+                    "error for 'general_log' table\n");
+    }
+    if (slow_log_table_exists)
+    {
+      if (!get_table_structure((char *) "slow_log",
+                               database, table_type, &ignore_flag) )
+        verbose_msg("-- Warning: get_table_structure() failed with some internal "
+                    "error for 'slow_log' table\n");
+    }
+  }
+  if (flush_privileges && using_mysql_db)
   {
     fprintf(md_result_file,"\n--\n-- Flush Grant Tables \n--\n");
     fprintf(md_result_file,"\n/*! FLUSH PRIVILEGES */;\n");