How to add parameters on '/_search' method like this '/_search?preference=zxcvzxd123'

[dap3ng]

Say the same user runs the same request twice in a row and documents do not come back in the same order both times, this is a pretty bad experience isn’t it? Unfortunately this is something that can happen if you have replicas (index.number_of_replicas is greater than 0). The reason is that Elasticsearch selects the shards that the query should go to in a round-robin fashion, so it is quite likely if you run the same query twice in a row that it will go to different copies of the same shard.
The recommended way to work around this issue is to use a string that identifies the user that is logged in (a user id or session id for instance) as a preference. This ensures that all queries of a given user are always going to hit the same shards, so scores remain more consistent across queries.

How to add parameters on '/_search' method like this '/_search?preference=zxcvzxd123'