From MySQL to Mongo data export: how to preserve creation date? - mysql

Question

I'm trying to export a MySQL table data to MongoDB, creating a set of "Create" statements in Rails.
My issue is this: in my original table I have "created_at" and "updated_at" fields and I would like to keep the original values even when I export the data to my new MongoDB document. But after I create a new row in Mongo, even if I tell it to set "created_at" = [my original date], Mongo sets it to the current datetime.
How can I avoid this? This is my MongoMapper model:
class MongoFeedEvent
include MongoMapper::Document
key :event_type, String
key :type_id, Integer
key :data, String
timestamps!
end

Answer 1

You're probably better off dumping your MySQL table as JSON and then using mongoimport to import that JSON; this will be a lot faster than doing it row by row through MongoMapper and it will bypass your problem completely as a happy side effect.
There's a gem that will help you dump your MySQL database to JSON called mysql2xxxx:
How to export a MySQL database to JSON?
I haven't used it but the author seems to hang out on SO so you should be able to get help with it if necessary. Or, write a quick one-off script to dump your data to JSON.
Once you have your JSON, you can import it with mongoimport and move on to more interesting problems.
Also, mongoimport understands CSV and mysqldump can write CSV directly:
The mysqldump command can also generate output in CSV, other delimited text, or XML format.
So skip MongoMapper and row-by-row copying completely for the data transfer. Dump your data to CSV or JSON and then import that all at once.