For loading huge amounts of data into MySQL, LOAD DATA INFILE is by far the fastest option. Unfortunately, while this can be used in a way INSERT IGNORE or REPLACE works, ON DUPLICATE KEY UPDATE is not currently supported.
However, ON DUPLICATE KEY UPDATE
has advantages over REPLACE
. The latter does a delete and an insert when a duplicate exists. This brings overhead for key management. Also, autoincrement ids will not stay the same on a replace.
How can ON DUPLICATE KEY UPDATE
be emulated when using LOAD DATA INFILE?
Best Answer
These steps can be used to emulate this functionality:
1) Create a new temporary table.
2) Optionally, drop all indices from the temporary table to speed things up.
3) Load the CSV into the temporary table
4) Copy the data using ON DUPLICATE KEY UPDATE
5) Remove the temporary table
Using
SHOW INDEX FROM
andSHOW COLUMNS FROM
this process can be automated for any given table.