Elasticsearch indexing while rollover

Question

I have an application which writes to the ES and which also schedules time based index rollover based on max_docs condition.

• What will happen if I try indexing during the rollover ?
• Does ES takes lock while performing rollover ?
• On an average how much time does it take to rollover the index ? Acc. to me this shouldn't take much time as time based index rollover is just creating a new index and pointing the alias to it.

Answer 1

I asked this question on elastic discuss and it got answered there.

Copying the answer here :

Remember that you are sending your index operation to an alias.

What happens when you rollover:

• It creates a new index (You are still indexing to the old index through the alias).
• It switches the alias. This switch is super fast. If you have a pending operation it might go to the old index.

Once done, the new requests will go to the new index.

There is no lock.

For reference : link