Does Elasticsearch execute operations in a specific order?-CodePudding

I read that ES is near real-time, and therefore all index/create/update/delete etc. operations are not executed immediately.

Let's say I index 3 documents with same id, in this order with 1 millisecond between each, and then force refresh:

{
  "_id": "A",
  "_source": { "text": "a" }
}

{
  "_id": "A",
  "_source": { "text": "b" }
}

{
  "_id": "A",
  "_source": { "text": "c" }
}

Then, if I search for a document with id "A", I will get 1 result, but which one?

When Elasticsearch performs a refresh, does it execute operations sequentially in the order in which they arrive?

CodePudding user response：

in this instance it will come down to which indexing approach you take

a bulk request does not guarantee the order that you submitted it in is how it will be applied. it might be in the same order with (some of) your tests, but there's no guarantee that Elasticsearch provides there

you can manage this by specifying a version in your document, so a higher version of a document is always going to be what is indexed

indexing using 3 individual POSTs will be ordered, as you are making 3 separate and sequential requests one after the other. that's because each request has the same _id and will be directed to the same shard and actioned by the order they are received in