How long should a 20GB restore take in MySQL? (A.k.a. Is something broken?)

Question

I'm trying to build a dev copy of a production MySQL database by loading one of the backups. How long should it take to do this if the uncompressed dump is ~20G?

This command has been running for something like 24h with 10% CPU load and I'm wondering if it's just slow or if it/I am doing something wrong.

mysql -u root -p < it_mysql_dump.sql 

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BTW it's on a beefy desktop dev machine with plenty of ram, but it might be reading and writing the same HDD. I think I'm using InnoDB.

Answer 1

Open another terminal, run mysql, and count the rows in some of the tables in your dump (SELECT COUNT(*) FROM table). Compare to the source database. That'll tell you the progress.

I INSERTed about 80GB of data into MySQL over a network in about 14 hours. They were one-insert-per-row dumps (slow) with a good bit of overhead, inserting on a server with fast disks.

24 hours is possible if the hardware is old enough, or your import is competing with something else for disk IO and memory.

Answer 2

I just went through the experience of restoring a 51.8 Gb database from a 36.8 Gb mysqldump file to create an imdb database. For me the restore which was not done over the network but was done from a file on the native machine took a little under 4 hours.

The machine is a Quad Core Server running Windows Server 2008. People have wondered if there is a way to monitor progress. There actually is. You can watch the restore create the database files by going to the Program Data directory and finding the MYSQL subdirectory and then finding the subdirectory with your database name.

The files are gradually built in the directory and you can watch them build up. No small comfort when you have a production issue and you are wondering if the restore job is hung up or just taking a long time.