what is storage model migration?

[kjuice276]

I'm making some changes to existing storage models and what is this storage model migration?

@Nik-09

[Nik-09]

Hi @kjuice276 great question, basically migrations here mean modifying data that are already present in the production servers.
Imagine we are removing an existing field (say X) from the exploration. To make changes we modify the model layer code i.e., ExplorationModel class at the same time we also want to update all the ExplorationModel instances that are present in the Oppia production database. Thus we need to migrate the data from the old structure to the new structure and to do that we need to run beam jobs particularly exp_migration_job.

let me know if you have any more questions.
thanks

[kjuice276]

here we need to write code?

[kjuice276]

@Nik-09 this jobs https://github.com/oppia/oppia/wiki/Apache-Beam-Jobs ???

[rahat2134]

@seanlip is there any purpose of not closing these types of discussions which are already answered?

[seanlip]

It's fine to close such discussions if they're already answered. Thanks for checking.