activerecord - rails - Prefetching records to process in a queue -

i have active record relation defined this:

contacts = contact.where("status = 'waiting'") 

then, following:

if contacts      batch_id = randomstringoflength(32)      #set processing     contacts.update_all(status: 'processing', batch_id: batch_id)      #todo: best way this?      contacts = contact.where("batch_id = ?", batch_id)      contacts.each |contact|           executefor(contact)      end end 

as can see, i'm having update records specific batch_id in order later able fetch them.

this because first instance of contacts doesn't fetch records. first database call update status processing , fetching them batch_id allows me run each loop.

is there better way this? although have indexed batch_id think there might better way in rails.

if don't update batch_id , remove line fetch batch_id, .each not return because status updated.

thanks

if not need batch_id in database can write following:

contacts = contact.where(status: 'waiting') if contacts      #set processing     contacts.update_all(status: 'processing')      #todo: best way this?      contacts = contact.where(status: 'processing')      contacts.each |contact|          executefor(contact)     end end 

and option may little bit faster:

if contact.where(status: 'waiting').update_all(status: 'processing') > 0     contacts = contact.where(status: 'processing')      contacts.each |contact|          executefor(contact)     end end 

do not forget check indexes on database. status needs one.

keeping batch_id:

batch_id = randomstringoflength(32) if contact.where(status: 'waiting').update_all(status: 'processing', batch_id: batch_id) > 0     contacts = contact.where(batch_id: batch_id)      contacts.each |contact|          executefor(contact)     end end