The patterns for the
bulk APIs are similar to those for
individual documents. The difference is that the requesting node knows in
which shard each document lives. It breaks up the multi-document request into
a multi-document request per shard, and forwards these in parallel to each
Once it receives answers from each node, it collates their responses into a single response, which it returns to the client.
.Retrieving multiple documents with
image::images/04-05_mget.png["Retrieving multiple documents with mget"]
Below we list the sequence of steps necessary to retrieve multiple documents
with a single
mget request, as depicted in <
The client sends an
Node 1builds a multi-get request per shard, and forwards these requests in parallel to the nodes hosting each required primary or replica shard. Once all replies have been received,
Node 1builds the response and returns it to the client.
routing parameter can be set for each document in the
preference parameter can be set for the top-level
.Multiple document changes with
image::images/04-06_bulk.png["Multiple document changes with bulk"]
Below we list the sequence of steps necessary to execute multiple
update requests within a single
bulk request, as depicted in <
The client sends a
Node 1builds a bulk request per shard, and forwards these requests in parallel to the nodes hosting each involved primary shard.
The primary shard executes each action serially, one after another. As each action succeeds, the primary forwards the new document (or deletion) to its replica shards in parallel, then moves on to the next action. Once all replica shards report success for all actions, the node reports success to the requesting node, which collates the responses and returns them to the client.
bulk API also accepts the
at the top-level for the whole
bulk request, and the
in the metadata for each request.