[Feature Request] [Active record] - Add order option to "find_in_batches" and

[佑馬光吉]

Currently, if "primary_key" does not exist, "find_in_batches" and "find_each" will result in an error.

Since there may be cases where "primary_key" does not exist when performing batch processing,

I think that it can be solved by adding an order option.

[Alberto Almagro]

Hi,

in my opinion I would order by something in cases where few objets are retrieved from DB, for example when showing a result on a template to an end user. On the other side I would use find_in_batches or find_each for background jobs or queries dealing with lots of objects to reduce memory consumption... and in those cases I don't feel like any order is needed. Why do you think it is important to have them ordered?

Kind regards,

Alberto Almagro

[Tchoum Tux]

it might be necessary to replay ordered events stored in DB

[James Coleman]

Fundamentally it’s not efficiently possible to find items in batches without a unique orderable value and and defined ordering by that value, because otherwise you’d have to always include a list excluding everything else you’ve already gotten (and even then you’d need a unique value/set of columns to do that). 

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