cecyc/adding_indexes_sql.md

## adding_indexes_sql.md

      
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              adding_indexes_sql.md
            
          
    How to add indexes in MySQL

Basics:
alter table NAME add index <column>
The above works if you are adding an index to just one column. If you need to index different variations:
alter table NAME add index INDEXNAME(things,to,index)
If you need to alter an existing index, you will need to drop it first, then recreate it.
alter table NAME drop index INDEXNAME
If you need to look up existing index data, you can:
show create table NAME
This will show existing keys.
Full example:
alter table TABLENAME
drop index foo, 
add index foo(foo,bar), ALGORITHM=INPLACE;

If there are issues while performing this, you couldshow process list; and then kill X where X is the id of the process, to terminate it.