MySQL quotation sentence is unlocked: algorithm=insert, lock=none

Add index without lock on line ： Quoted statements are unlocked

ALTER TABLE tbl_name ADD PRIMARY KEY (column), ALGORITHM=INPLACE, LOCK=NONE;

ALGORITHM=INPLACE
 Better solutions , Index the current table , step ：
1. Create index ( Secondary indexes ) The data dictionary 
2. Add shared table lock , prohibit DML, Allow queries 
3. Read cluster index , Construct a new index entry , Sort and insert 
 Enter new index 
4. Wait for all read-only transactions that open the current table to commit 
5. End of index creation 
 
ALGORITHM=COPY
 Create an index from a temporary table , Need twice as much storage , And more IO, step ：
1. New with index （ primary key ） A temporary watch 
2. Lock the original watch , prohibit DML, Allow queries 
3. Copy the original table data to the temporary table 
4. Read and write prohibited , Conduct rename, Upgrade dictionary lock 
5. Finish creating index 
 
LOCK=DEFAULT： Default mode ,MySQL Decide for yourself which one to use LOCK Pattern , Try not to lock the watch 
LOCK=NONE： unlocked ： allow Online DDL Concurrent read and write operations are performed during . If Online DDL fuck 
 Continue writing to the table is not supported , be DDL operation failed , Invalid for table modification 
LOCK=SHARED： Shared lock ：Online DDL Write blocked during operation , Does not affect reading 
LOCK=EXCLUSIVE： Exclusive lock ：Online DDL No operation is allowed on the lock table during operation 

Then I found a solution with the help of alicloud

• In-Place？： Corresponding DDL Of the statement Algorithm Options , adopt inplace How to execute DDL. Compared with the table copy method , Can reduce space and I/O Consume .
• Copies Table？： Corresponding DDL Of the statement Algorithm Options , adopt Table copy How to execute DDL.DDL During execution, it will occupy more disk space and consume more I/O.
• Allow concurrency DML？： Corresponding DDL Of the statement Lock Options ,DDL Whether concurrency is supported during execution DML operation .
• Allow concurrent queries ？：DDL Whether concurrent query operations are supported during statement execution （ It is usually supported ）.
• MySQL Please refer to the official documents ：Online DDL overview
• DDL The metadata of the table needs to be modified during operation execution （metadata）, You may encounter the situation of waiting for the metadata lock of the table （waiting for table metadata lock）, Please refer to ：RDS MySQL On the table Metadata lock Generation and treatment of
• Inplace and Copy Table It's the opposite 2 There are ways to deal with it ; But even if DDL Support Inplace Options , Some operations also involve table copying in the whole execution process , For example, add columns in the above table .