Deprecate rest_total_hits_as_int

[jtibshirani]

We introduced the search parameter rest_total_hits_as_int in #35849 to provide a smooth upgrade path from the old syntax. Now that 8.0 is approaching, we should come up with a plan to deprecate this parameter.

When we discussed as a team, we decided not to deprecate in 7.x and remove in 8.0. The parameter is still widely used and removing it in 8.0 would be too disruptive. So maybe we could deprecate in 8.x and give a long period before removing it.

Note there are many REST tests that still use rest_total_hits_as_int, so the deprecation may take some effort. Some other components like Watcher also still use the parameter (#38387).

[elasticmachine]

Pinging @elastic/es-search (Team:Search)

[JacobBrandt]

If you plan to remove this parameter how does one get an accurate total hit count?

[jtibshirani]

@JacobBrandt we added the track_total_hits parameter for this purpose. You'll get back total_hits as JSON, but the value will always be exact (relation will always be eq).

[JacobBrandt]

You mean the parameter that doesn't exist on Multi Search?

My concern is that with Kibana removing the ability to do batch requests is Elasticsearch going to do the same thing with Multi Search at some point since Multi Search is going to lose the only parameter that allows one to get accurate hit counts.

[jtibshirani]

@JacobBrandt msearch supports track_total_hits, it just needs to be specified in the search body. Here's an example:

GET index/_msearch
{"index": "index"}
{"query" : {"match_all": {}}, "track_total_hits": true}

Does this address your question (I might not be fully understanding it)?

[JacobBrandt]

Oh...that actually makes a lot of sense now that I see that. Thanks.

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)