Question

I need to restore a dumped database, but without discarding existing rows in tables.

To dump I use:

mysqldump -u root --password --databases mydatabase > C:\mydatabase.sql

To restore I do not use the mysql command, since it will discard all existing rows, but instead mysqlimport should do the trick, obviously. But how? Running:

mysqlimport -u root -p mydatabase c:\mydatabase.sql

says “table mydatabase.mydatabase does not exist”. Why does it look for tables? How to restore dump with entire database without discarding existing rows in existing tables? I could dump single tables if mysqlimport wants it.

What to do?

Answer 1

If you are concerned with stomping over existing rows, you need to mysqldump it as follows:

MYSQLDUMP_OPTIONS="--no-create-info --skip-extended-insert"
mysqldump -uroot --ppassword ${MYSQLDUMP_OPTIONS} --databases mydatabase > C:\mydatabase.sql

This will do the following:

• remove CREATE TABLE statements and use only INSERTs.
• It will INSERT exactly one row at a time. This helps mitigate rows with duplicate keys

With the mysqldump performed in this manner, now you can import like this

mysql -uroot -p --force -Dtargetdb < c:\mydatabase.sql

Give it a Try !!!

WARNING : Dumping with --skip-extended-insert will make the mysqldump really big, but at least you can control each duplicate done one by one. This will also increase the length of time the reload of the mysqldump is done.