A.10.39. How do I continue to send queries in the event that one of the SQL nodes fails? 

MySQL NDB Cluster does not provide any sort of automatic failover between SQL nodes. Your application must be prepared to handle the loss of SQL nodes and to fail over between them. 

A.10.40. How do I back up and restore an NDB Cluster? 

You can use the NDB Cluster native backup and restore functionality in the NDB management client and the ndb_restore  program. See Section 23.5.8, “Online Backup of NDB Cluster” , and Section 23.4.23, “ndb_restore — Restore an NDB Cluster Backup” . 

You can also use the traditional functionality provided for this purpose in mysqldump  and the MySQL server. See Section 4.5.4, “mysqldump — A Database Backup Program” , for more information. 

A.10.41. What is an “angel process” ? 

This process monitors and, if necessary, attempts to restart the data node process. If you check the list of active processes on your system after starting ndbd , you can see that there are actually 2 processes running by that name, as shown here (we omit the output from ndb_mgmd  and ndbd  for brevity): 

shell> ./ndb_mgmd shell> ps aux | grep ndb me 23002 0.0 0.0 122948 3104 ? Ssl 14:14 0:00 ./ndb_mgmd me 23025 0.0 0.0 5284 820 pts/2 S+ 14:14 0:00 grep ndb shell> ./ndbd -c 127.0.0.1 --initial shell> ps aux | grep ndb me 23002 0.0 0.0 123080 3356 ? Ssl 14:14 0:00 ./ndb_mgmd me 23096 0.0 0.0 35876 2036 ? Ss 14:14 0:00 ./ndbmtd -c 127.0.0.1 --initial me 23097 1.0 2.4 524116 91096 ? Sl 14:14 0:00 ./ndbmtd -c 127.0.0.1 --initial me 23168 0.0 0.0 5284 812 pts/2 R+ 14:15 0:00 grep ndb 

The ndbd  process showing 0.0  for both memory and CPU usage is the angel process (although it actually does use a very small amount of each). This process merely checks to see if the main ndbd or ndbmtd  process (the primary data node process which actually handles the data) is running. If permitted to do so (for example, if the StopOnError  configuration parameter is set to false ), the angel process tries to restart the primary data node process. 

## A.11 MySQL 8.0 FAQ: MySQL Chinese, Japanese, and Korean Character Sets 

This set of Frequently Asked Questions derives from the experience of MySQL’s Support and Development groups in handling many inquiries about CJK (Chinese-Japanese-Korean) issues. 

A.11.1 What CJK character sets are available in MySQL? .............................................................. 5258 

A.11.2 I have inserted CJK characters into my table. Why does SELECT  display them as “?” characters? ......................................................................................................................... 5259 

A.11.3 What problems should I be aware of when working with the Big5 Chinese character set? ....... 5261 

A.11.4 Why do Japanese character set conversions fail? ............................................................... 5261 

A.11.5 What should I do if I want to convert SJIS 81CA  to cp932 ? ................................................. 5262 

A.11.6 How does MySQL represent the Yen ( ¥ ) sign? ................................................................... 5262 

A.11.7 Of what issues should I be aware when working with Korean character sets in MySQL? ......... 5263 

A.11.8 Why do I get Incorrect string value  error messages? .............................................. 5263 

