# Strange reindex behaviour

**URL:** <https://discuss.elastic.co/t/strange-reindex-behaviour/274108>\
**Category:** Elasticsearch\
**Tags:** reindex\
**Created:** [May 26, 2021, 6:38pm UTC](https://discuss.elastic.co/t/strange-reindex-behaviour/274108 "2021-05-26T18:38:04Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![leandrojmp](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/leandrojmp/32/107231_2.png) [@leandrojmp](https://discuss.elastic.co/u/leandrojmp)\
**Post date:** [May 26, 2021, 6:38pm UTC](https://discuss.elastic.co/t/strange-reindex-behaviour/274108/1 "2021-05-26T18:38:04Z")

</div>

I'm doing some reindex of daily index to monthly ones and sometimes the reindex process enters in a loop and starts again after it already reindexed the documents.

For example, considering the index `indexName-2021.05.01` with 500.000 documents and reindexing it into `indexName-2021.05`, I start the reindex process with the following request:

```auto
POST _reindex
{
  "source": {
    "index": "indexName-2021.05.01"
  },
  "dest": {
    "index": "indexName-2021.05"
  }
}

```

Then I use `GET _tasks?actions=*reindex&detailed` to get the task id and `GET _tasks/taskID` to monitor the progress.

I can see the `created` number increasing as expected.

```auto
          "status" : {
            "total" : 500000,
            "updated" : 0,
            "created" : 184000,
            "deleted" : 0,
            "batches" : 184,
            "version_conflicts" : 0,
            "noops" : 0,
            "retries" : {
              "bulk" : 0,
              "search" : 0
            }

```

I also use the Discover in Kibana to compare the documents, in one tab I filter by the daily index and in the other i filter by the monthly index, both using the same time interval, which correspond the the time interval present in the daily index.

After sometime I check again for the progress using the task id and got an answer saying that the task doesn't exist anymore, from discover I can see that all documents were reindexed as expected.

But if I run `GET _tasks?actions=*reindex&detailed` to get the tasks running I can see few tasks doing reindex for the same index, but now they show the `updated` part of the status response increasing.

```auto
          "status" : {
            "total" : 500000,
            "updated" : 175000,
            "created" : 0,
            "deleted" : 0,
            "batches" : 175,
            "version_conflicts" : 0,
            "noops" : 0,
            "retries" : {
              "bulk" : 0,
              "search" : 0
            }

```

My question is: What can cause this to happen since the documents were already indexed?

Sometimes this reindex loop takes a long time, which makes the load and CPU of the nodes doing the reindex process to increase a lot.

Normally when this happens and I can confirm that all the documentes were reindexed, I cancel all the reindex tasks using:

```auto
POST _tasks/_cancel?actions=*reindex

```

But I would like to know why this is happening and how to avoid it.

I'm currently running version 7.9.3, an upgrade to 7.12.1 is planned for the next weeks.

---

<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 23, 2021, 6:38pm UTC](https://discuss.elastic.co/t/strange-reindex-behaviour/274108/2 "2021-06-23T18:38:07Z")

</div>

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