Data indexing process taking a lot of time


I have 9000 documents in my ES index .

I want to sort by an analyzed string field, so, in order to do that i knew ( through Google ) that i must update the mapping to make the field not-analyzed so i can sort by this field and i must re-index the data again to reflect the change in mapping .

The re-indexing process consumed about 20 minutes on my machine .

The strange thing is that the re-indexing process consumed about 2 hours on a very powerful production server !!!

I checked the memory status and the processor usage on that server and everything was normal ..

  • What i want to know is :

1- Is there a way to sort documents by an analyzed, tokenized field without re-indexing the whole documents ?

2- If i must re-index the whole documents, then why does it take such huge time to re-index the documents on the server ?? or how to trace the slowness reason on that server ???