Ghostferry is a library that enables you to selectively copy data from one mysql instance to another with minimal amount of downtime.
It is inspired by Github's gh-ost, although instead of copying data from and to the same database, Ghostferry copies data from one database to another and has the ability to only partially copy data.
There is an example application called ghostferry-copydb included (under the
copydb directory) that demonstrates this library by copying an entire
database from one machine to another.
Talk to us on IRC at irc.freenode.net #ghostferry.
- Tutorial and General Documentations: https://shopify.github.io/ghostferry
- Code documentations: https://godoc.org/github.com/Shopify/ghostferry
An overview of Ghostferry's high-level design is expressed in the TLA+
specification, under the tlaplus directory. It may be good to consult with
that as it has a concise definition. However, the specification might not be
entirely correct as proofs remain elusive.
On a high-level, Ghostferry is broken into several components, enabling it to copy data. This is documented at https://shopify.github.io/ghostferry/master/technicaloverview.html
dev up
- Have Docker installed
- Clone the repo
docker-compose up -dnix-shell
make test
make copydb && ghostferry-copydb -verbose examples/copydb/conf.json- For a more detailed tutorial, see the documentation.
Kindly take note of following options:
DEBUG=1: To see more detailed debug output byGhostferrylive, as opposed to only when the test fails. This is helpful for debugging hanging test.
Example:
DEBUG=1 ruby test/main.rb -v -n "TrivialIntegrationTests#test_logged_query_omits_columns"