These performance tips supplement the general guidelines for fast inserts in Section 126.96.36.199, “Optimizing INSERT Statements”.
When importing data into
InnoDB, turn off autocommit mode, because it performs a log flush to disk for every insert. To disable autocommit during your import operation, surround it with
SET autocommit=0; ... SQL import statements ... COMMIT;
If you have
UNIQUEconstraints on secondary keys, you can speed up table imports by temporarily turning off the uniqueness checks during the import session:
SET unique_checks=0; ... SQL import statements ... SET unique_checks=1;
For big tables, this saves a lot of disk I/O because
InnoDBcan use its change buffer to write secondary index records in a batch. Be certain that the data contains no duplicate keys.
If you have
FOREIGN KEYconstraints in your tables, you can speed up table imports by turning off the foreign key checks for the duration of the import session:
SET foreign_key_checks=0; ... SQL import statements ... SET foreign_key_checks=1;
For big tables, this can save a lot of disk I/O.
Use the multiple-row
INSERTsyntax to reduce communication overhead between the client and the server if you need to insert many rows:
INSERT INTO yourtable VALUES (1,2), (5,5), ...;
This tip is valid for inserts into any table, not just
When doing bulk inserts into tables with auto-increment columns, set
innodb_autoinc_lock_modeto 2 instead of the default value 1. See Section 188.8.131.52, “AUTO_INCREMENT Handling in InnoDB” for details.
When performing bulk inserts, it is faster to insert rows in
InnoDBtables use a clustered index, which makes it relatively fast to use data in the order of the
PRIMARY KEY. Performing bulk inserts in
PRIMARY KEYorder is particularly important for tables that do not fit entirely within the buffer pool.