DROP INDEX Statement 2612 DROP LOGFILE GROUP  is useful only with Disk Data storage for NDB Cluster. See Section 23.5.10, “NDB Cluster Disk Data Tables” . The required  ENGINE  clause provides the name of the storage engine used by the log file group to be dropped. Currently, the only permitted values for  engine_name  are  NDB  and  NDBCLUSTER . Before dropping a log file group, you must drop all tablespaces that use that log file group for  UNDO  logging. Important This statement drops the log file group named  logfile_group . The log file group must already exist or an error results. (For information on creating log file groups, see Section 13.1.16, “CREATE LOGFILE GROUP Statement” .) DROP LOGFILE GROUP  logfile_group ENGINE [=]  engine_name 13.1.28 DROP LOGFILE GROUP Statement MySQL NDB Cluster supports online operations using the same  ALGORITHM=INPLACE  syntax supported in the standard MySQL Server. See Section 23.5.11, “Online Operations with ALTER TABLE in NDB Cluster” , for more information. ALGORITHM  and  LOCK  clauses may be given to influence the table copying method and level of concurrency for reading and writing the table while its indexes are being modified. They have the same meaning as for the  ALTER TABLE  statement. For more information, see Section 13.1.9, “ALTER TABLE Statement” Indexes on variable-width columns of  NDB  tables are dropped online; that is, without any table copying. The table is not locked against access from other NDB Cluster API nodes, although it is locked against other operations on the  same  API node for the duration of the operation. This is done automatically by the server whenever it determines that it is possible to do so; you do not have to use any special SQL syntax or server options to cause it to happen. DROP INDEX ‘PRIMARY‘ ON t; To drop a primary key, the index name is always  PRIMARY , which must be specified as a quoted identifier because  PRIMARY  is a reserved word: DROP INDEX  drops the index named  index_name  from the table  tbl_name . This statement is mapped to an  ALTER TABLE  statement to drop the index. See Section 13.1.9, “ALTER TABLE Statement” . DROP INDEX  index_name  ON  tbl_name [ algorithm_option  |  lock_option ] ... algorithm_option : ALGORITHM [=] {DEFAULT | INPLACE | COPY} lock_option : LOCK [=] {DEFAULT | NONE | SHARED | EXCLUSIVE} 13.1.27 DROP INDEX Statement •For information about dropping loadable functions, see Section 13.7.4.2, “DROP FUNCTION Statement for Loadable Functions” . •For information about dropping stored functions, see Section 13.1.29, “DROP PROCEDURE and DROP FUNCTION Statements” .