Java Google App Engine inconsistent data lose after restarting dev server

Question

Hello everyone,

I am using Java GAE. So far, i'm just scafolding my data objects and i'm seeing an interesting issue.

• The records that i am playing around with are getting updated properly as long as my dev server is running up. The second that the my dev server gets restarted, i lose all of my changes.
• That would be not alarming if i lost all of my records, but, there was a point of time where my data persisted through the server restart. I'm worried that i would lose production data if i launched without fixing this potential bugs?

ANy idea on wher ei should look?

Answer 1

The datastore is persisted between instances as described here. The Java SDK doesn't have any functionality to clear the datastore for you, so you, or something working on your behalf (eg, your build process) must be deleting it.

Answer 2

Sounds like local development environment problem. Check the location of local_db.bin and ensure your build process does not touch the database file. Maybe the restart happens before the data has been persisted? The local development datastore is not stable like local relational databases. E.g. after upgrading appengine sdk versions the old local datastore might not work at all.

Answer 3

How are you starting the dev server? Make sure you're not providing "c" or "clear" as a flag, which does erase all the persisted data.