使用大量数据进行更新查询以避免锁定等待超时的良好做法是什么？

Question

So basically, I have this current query :

UPDATE act AS a
INNER JOIN blok AS b
ON b.fav_pat = a.pat_id
SET a.blok_id = b.id

Because of the volumn of data i have, its currently timing out. is there a way around to avoid the time out without modifying db config ?

Answer 1

The flyway package you use does its best to allow any incomplete operation to be entirely rolled back using the host RDBMS's transaction semantics. That means it is designed to do update operations like the one you showed us in an ACID-compliant single transaction.

If the tables involved are large (millions of rows or more) the transactions can be very large. They can make your MySQL server thrash, spilling transaction logs to disk or SSD. Committing those transaction logs can take a very long time. You didn't mention row counts, but if they are large is is possible that flyway is not the right tool for this job.

Your lock timeout hints that you are doing this operation on a database with other concurrent activity. You may want to do it on an otherwise quiet database for best results.

You can increase the lock wait timeout by doing this.

show variables like 'innodb_lock_wait_timeout'; -- previous vale
SET GLOBAL innodb_lock_wait_timeout = 300; -- five min

Then, perhaps, try again, just before sunrise on a holiday or another quiet time. More information here .

Consider restoring the lock timeout to its previous value when your flyway job is done.

You can also consider doing your update in batches, for example 1000 rows at a time. But flyway doesn't seem to support that. If you go that route you can ask another question.