> For the complete documentation index, see [llms.txt](https://hezhiqiang.gitbook.io/elasticsearch/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hezhiqiang.gitbook.io/elasticsearch/distributed_crud/retrieving.md).

# 获取

A document can be retrieved from a primary shard or from any of its replicas.

\[\[img-distrib-read]] .Retrieving a single document image::images/04-03\_get.png\["Retrieving a single document"]

Below we list the sequence of steps to retrieve a document from either a primary or replica shard, as depicted in <>:

1. The client sends a get request to `Node 1`.
2. The node uses the document's `_id` to determine that the document belongs to shard `0`. Copies of shard `0` exist on all three nodes. On this occasion, it forwards the request to `Node 2`.
3. `Node 2` returns the document to `Node 1` which returns the document to the client.

For read requests, the requesting node will choose a different shard copy on every request in order to balance the load -- it round-robins through all shard copies.

It is possible that a document has been indexed on the primary shard but has not yet been copied to the replica shards. In this case a replica might report that the document doesn't exist, while the primary would have returned the document successfully.