# Multiget (mget) API performance

**URL:** <https://discuss.elastic.co/t/multiget-mget-api-performance/289813>\
**Category:** Elasticsearch\
**Created:** [November 22, 2021, 2:15pm UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813 "2021-11-22T14:15:09Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![jon\_cabrera](https://avatars.discourse-cdn.com/v4/letter/j/ec9cab/32.png) [@jon\_cabrera](https://discuss.elastic.co/u/jon_cabrera)\
**Post date:** [November 22, 2021, 2:15pm UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813/1 "2021-11-22T14:15:09Z")

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Hello!

I am working on a search engine and I have introduced the use of the `mget` API to obtain a series of documents from a series of ids.

My question is related to a series of issues that I have been able to observe in the performance of this type of search.

The average time of the requests that use `mget` is higher than the rest of the requests that use other operations of the Elasticsearch API. A sample of these times and their operations could be this:

- `_mget` API -\> ` **30-40ms** `
- `_search` API -\> `20-30ms`
- `_count` API -\> `16-18ms`
- `get` API (for an specified document) -\> `5-6ms`

Is this behavior normal? Before introducing the use of `mget`, I thought that the performance would be at least similar to that of the `search` API. Sometimes the difference between both endpoints is greater than `10ms`.

In many of these cases, information is being obtained from approximately 1 to 20 documents.

On the other hand we see that in addition to these average times there are also times that seem to be quite high. A small percentage (~1%) seem to have times between `200ms-2000ms`.  
Is there a way to lower the times of these requests?

To analyze the `mget` response times we had to monitor the response times of the `http` layer of the microservice developed to expose a rest interface that in turn makes use of the `mget` API through a Java client. Is there any utility to be able to make a direct profile of this type of request? If I'm not mistaken, the `profile` API is only available for `_search`.

My index has 14-16M of documents and i'm using 7.10 version. We need to retrieve the source of each document and we don't request stored fields. This is an example of the query that I'm performing:

```auto
POST http://localhost:9200/_mget
Content-Type: application/json

{
  "docs": [
    {
      "_index": "<my_index>",
      "_type": null,
      "_id": "<some_id>",
      "routing": null,
      "stored_fields": null,
      "version": -3,
      "version_type": "internal",
      "_source": null
    }
  ]
}

```

Thanks!

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<div class="post-metadata">

**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [November 23, 2021, 12:22am UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813/2 "2021-11-23T00:22:24Z")

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> [@jon\_cabrera](#):
>
> Is this behavior normal?

Yep, because you're basically doing `N` gets, each of which take time to run and then be collated. And the overall response is only going to be as fast as the slowest one.

> [@jon\_cabrera](#):
>
> A small percentage (~1%) seem to have times between `200ms-2000ms` .  
> Is there a way to lower the times of these requests?

At a guess, that could be a cache miss. I am not sure you can do much about those tbh.

> [@jon\_cabrera](#):
>
> If I'm not mistaken, the `profile` API is only available for `_search` .

[Correct](https://www.elastic.co/guide/en/elasticsearch/reference/7.15/search-profile.html);

> Any `_search` request can be profiled by adding a top-level `profile` parameter:

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<div class="post-metadata">

**Author:** ![jon\_cabrera](https://avatars.discourse-cdn.com/v4/letter/j/ec9cab/32.png) [@jon\_cabrera](https://discuss.elastic.co/u/jon_cabrera)\
**Post date:** [November 23, 2021, 11:23am UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813/3 "2021-11-23T11:23:18Z")

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Thanks for your answer. Is there an alternative to `mget` to be able to obtain documents by id that can improve performance in this case? Any way to improve cache behavior?

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**Author:** ![Christian\_Dahlqvist](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/christian_dahlqvist/32/4617_2.png) [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)\
**Post date:** [November 23, 2021, 11:53am UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813/4 "2021-11-23T11:53:11Z")

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Are all the different types of queries returning the same number of raw documents?

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<div class="post-metadata">

**Author:** ![jon\_cabrera](https://avatars.discourse-cdn.com/v4/letter/j/ec9cab/32.png) [@jon\_cabrera](https://discuss.elastic.co/u/jon_cabrera)\
**Post date:** [November 23, 2021, 2:02pm UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813/5 "2021-11-23T14:02:22Z")

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When looking with `_search` I normally use `from / size` parameters to return 30 documents. With `_mget` i'm requesting from 1 to 20 documents approximately.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [December 21, 2021, 2:02pm UTC](https://discuss.elastic.co/t/multiget-mget-api-performance/289813/6 "2021-12-21T14:02:28Z")

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