On-the-fly-Schema Migration for MongoDB. If you want to download without logging into slideshare, please do so from http://healthycodemagazine.com/articles/download?fileName=MidasTouch_Dhaval_June2014

1. Healthy Code June 201424
So what does Midas do?
Zero downtime deployment
and only one of the sites is active at any given time.
Give your Mongo
docs a Midas Touch!
roll their own schema migration infrastructure or use
data without downtime (unacceptable from SLA stand-
introduces you to Midas and talks about the runtime
Figure 01: Midas at work

2. Healthy CodeJune 2014 25
Let’s
the new schema .
Article
As we ar
use transactions
db.orders. (‘dispatch’:{ status :
})
use users
db.customers.remove(‘[“address.line3”]’)

3. Healthy Code June 201426
. When
date, etc.
use transactions
db.orders. (“dispatch.date”,
”{$date:[‘dd-MMM-yy’,’15-Aug-14’]}”)
a convention for naming change set directory.
// 03_upperCaseCatalogItemNameAndModifyDescrip-
tion.delta
use
db.items. (‘itemName’,’{$toUpper:
“$itemName” }’)
db.items. (‘description’,’$concat:
[“$itemName”, “Description”, $description”]’)
No Leaky Abstractions
on evolving the domain model and free them from
Caveats

4. Healthy CodeJune 2014 27
move forward in time .
3. Why not rollback the database?
not bomb.
with?
release.
.
.
FAQ
1. What happens if a bug is discovered in the
deployed application?
2. How can documents that never got requested by
the application be migrated?
establishing environments, transitioning and orienting
within teams.
software-artisan.com.
artisan.com.
versions at the same time