Running pt-table-checksum with replicate-do-db option on I've read the documentation on percona page, but still a bit confused, especially about the --replicate option.

My setting is that the slave is only replicating certain databases from master, say db1 and db2. So I have this following line in the my.cnf file on slave host:

replicate-do-db=db1
replicate-do-db=db2


So when I use the tool, I know I need to pass --databases=db1, db2 as an option, but do I need to write the resulting checksum table into one of these dbs with --replicate=db1.checksum? I know by default it creates a database called percona and writes to percona.checksum, but since I'm not replicating all the databases, will it also create and write such a db on slave?

And after using the tool, should I be running USE db1 before dropping the checksum table on master so that this is logged and sent to slave?

I know this can be easily tested but when I read the documentation mentioning of causing replication failure scared me. I somehow screwed my local MySQL and only having access to this two servers. Appreciate your help.
But do I need to write the resulting checksum table into one of these dbs with --replicate=db1.checksum? 


Yes, you need. Otherwise it would not be replicated.


  And after using the tool, should I be running USE db1 before dropping the checksum table on master so that this is logged and sent to slave?


Yes.