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DROP INDEXindex_name ONtbl_name    [algorithm_option |lock_option] ...algorithm_option:    ALGORITHM [=] {DEFAULT | INPLACE | COPY}lock_option:    LOCK [=] {DEFAULT | NONE | SHARED | EXCLUSIVE}

DROP INDEX drops the index namedindex_name from the tabletbl_name. This statement is mapped to anALTER TABLE statement to drop the index. SeeSection 15.1.9, “ALTER TABLE Statement”.

To drop a primary key, the index name is alwaysPRIMARY, which must be specified as a quoted identifier becausePRIMARY is a reserved word:

DROP INDEX `PRIMARY` ON t;

Indexes on variable-width columns ofNDB 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 thesame 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.

ALGORITHM andLOCK 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 theALTER TABLE statement. For more information, seeSection 15.1.9, “ALTER TABLE Statement”

MySQL NDB Cluster supports online operations using the sameALGORITHM=INPLACE syntax supported in the standard MySQL Server. SeeSection 25.6.12, “Online Operations with ALTER TABLE in NDB Cluster”, for more information.