# Inconsistent results when sorting on index order

**URL:** <https://discuss.elastic.co/t/inconsistent-results-when-sorting-on-index-order/183014>\
**Category:** Elasticsearch\
**Created:** [May 28, 2019, 7:57am UTC](https://discuss.elastic.co/t/inconsistent-results-when-sorting-on-index-order/183014 "2019-05-28T07:57:45Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![val](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/val/32/138203_2.png) [@val](https://discuss.elastic.co/u/val)\
**Post date:** [May 28, 2019, 7:57am UTC](https://discuss.elastic.co/t/inconsistent-results-when-sorting-on-index-order/183014/1 "2019-05-28T07:57:45Z")

</div>

I have a weird situation on ES 5.6.3 when using `search_after` and sorting on index order using `_doc`. The following query exhibits the behavior (the query part is not important):

```
{
  "from": 0,
  "size": 25,
  "query": {
    ...
  },
  "_source": ["id"],
  "sort": [
    {
      "id": {
        "order": "asc"
      }
    },
    {
      "_doc": {
        "order": "asc"
      }
    }
  ],
  "search_after": [
    "955411180397631",
    "28526432"
  ]
}

```

When I execute the above query, I always get the same number of results (i.e. `hits.total` is consistent), however, the `hits` array is sometimes empty (which is correct and what I'm expecting):

```
{
  "took": 3,
  "timed_out": false,
  "_shards": {
    "total": 28,
    "successful": 28,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 25,
    "max_score": null,
    "hits": [
    ]
  }
}

```

And sometimes I get another result which I'm not expecting since the document with the id `955411180397631` was already contained in the previous response:

```
{
  "took": 10,
  "timed_out": false,
  "_shards": {
    "total": 28,
    "successful": 28,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 25,
    "max_score": null,
    "hits": [
      {
        "_index": "myindex",
        "_type": "doc",
        "_id": "955411180397631",
        "_score": null,
        "sort": [
          955411180397631,
          29499628
        ]
      }
    ]
  }
}

```

The way I'm fixing this now is by adding `?preference=_primary` to the URL. So it seems like the index order on the primary shard and replica shard where the document is stored is not consistent. The index order on the primary shard is `28526432` and the index order on the replica shard is `29499628`. So it seems that depending on the shard that gets hit by the coordinating node, I will either get the document (when replica is hit) or not (when primary is hit).

When using `?preference=_replica` I always get the additional document and when using `?preference=_primary` I never get it, which is what I'm expecting.

Is this behavior to be expected or is something wrong in our index?

---

<div class="post-metadata">

**Author:** ![val](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/val/32/138203_2.png) [@val](https://discuss.elastic.co/u/val)\
**Post date:** [May 28, 2019, 11:56am UTC](https://discuss.elastic.co/t/inconsistent-results-when-sorting-on-index-order/183014/2 "2019-05-28T11:56:14Z")

</div>

I'm wondering if setting `index.number_of_replicas` to 0 and back to 1 (i.e. making fresh copies of the primary shards) would take care of the issue as well and make sure that the index order on both the primary and replica shards are identical. Any thoughts?

---

<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:** [June 25, 2019, 11:56am UTC](https://discuss.elastic.co/t/inconsistent-results-when-sorting-on-index-order/183014/3 "2019-06-25T11:56:15Z")

</div>

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