Question

In the SHOW PROCESSLIST – it is showing about 30+ rows has been locked for a few seconds and then update.

Is there a way to speed it up faster to update?

Example:

+------+-----------------+-----------+----------------+---------+------+----------+-------------------------------------------------------------------------------
| Id   | User            | Host      | db             | Command | Time | State    | Info                                                                          
+------+-----------------+-----------+----------------+---------+------+----------+--------------------------------------------------------------------------------
|  265 | user            | localhost | xxxxxxxxxxxxxx | Query   |   15 | Updating | UPDATE data SET status = '1', error = 'Unknown error'  WHERE f= 0xxxxx    
|  269 | user            | localhost | xxxxxxxxxxxxxx | Query   |   17 | Updating | UPDATE data SET status = '1', error = 'Invalid ....'  WHERE f= 0xxx 
|  280 | user            | localhost | xxxxxxxxxxxxxx | Query   |    7 | Updating | UPDATE data SET status = 1  WHERE f = 0xxxx                                           
|  300 | user            | localhost | xxxxxxxxxxxxxx | Query   |    1 | Updating | UPDATE data SET status = '1', error = 'Unknown ....'  WHERE f= 0xx             
|  314 | user            | localhost | xxxxxxxxxxxxxx | Query   |   13 | Updating | UPDATE data SET status = '1', error = 'Invalid....'  WHERE f= 0xxxx
|  327 | user            | localhost | xxxxxxxxxxxxxx | Query   |   11 | Updating | UPDATE data SET status = '1', error = 'Unknown ....'  WHERE f= 0xxxx               
|  341 | user            | localhost | xxxxxxxxxxxxxx | Sleep   |    2 |          | NULL                                                                                        
|  350 | user            | localhost | xxxxxxxxxxxxxx | Query   |    7 | Updating | UPDATE data SET status = '1', error = 'Unknown ....'  WHERE f= 0xxx                
|  360 | user            | localhost | xxxxxxxxxxxxxx | Query   |    5 | Updating | UPDATE data SET status = 1  WHERE f = 0xxxx     

There are a lot of UPDATE – I am using InnoDB, some fields are index.

In the data table, there are over 500,000 rows need to be updated while it looping in PHP CLI script (running in background/process in Linux).

Answer 1

• Make sure the f column is indexed so the WHERE clause is using it. Otherwise you’ll scan the whole table for every UPDATE.

• Try to group updates so you can set many rows with one UPDATE instead of one row at a time.

• Make sure you’re not using autocommit. Try to execute multiple changes per transaction.

• Make sure you have tuned InnoDB. Most people use the default values for innodb_buffer_pool_size, innodb_log_file_size, and innodb_io_capacity. The default values are not tuned for high performance.

• Set innodb_flush_log_at_trx_commit=2 to reduce fsyncs, as @Paulo H. suggests.