# Clearing the concept of Translog

**URL:** <https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374>\
**Category:** Elasticsearch\
**Created:** [October 22, 2021, 12:12am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374 "2021-10-22T00:12:37Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Aniket\_Pant](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@Aniket\_Pant](https://discuss.elastic.co/u/Aniket_Pant)\
**Post date:** [October 22, 2021, 12:12am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374/1 "2021-10-22T00:12:37Z")

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In translog [documentation](https://www.elastic.co/guide/en/elasticsearch/reference/current/index-modules-translog.html#index-modules-translog) it is said that

> All index and delete operations are written to the translog after being processed by the internal Lucene index but before they are acknowledged

So i am not understanding what this line are saying

> after being processed by the internal Lucene index but before they are acknowledged

when a new document come it first write to in-memory buffer and translog but where is translog stored?either in memory or disk ?

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**Author:** ![stephenb](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/stephenb/32/40856_2.png) [@stephenb](https://discuss.elastic.co/u/stephenb)\
**Post date:** [October 22, 2021, 12:57am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374/2 "2021-10-22T00:57:07Z")

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Translog is durable / persisted on disk.

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**Author:** ![Aniket\_Pant](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@Aniket\_Pant](https://discuss.elastic.co/u/Aniket_Pant)\
**Post date:** [October 22, 2021, 2:53am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374/3 "2021-10-22T02:53:50Z")

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> [@Aniket\_Pant](#):
>
> In translog [documentation](https://www.elastic.co/guide/en/elasticsearch/reference/current/index-modules-translog.html#index-modules-translog) it is said that
> 
> > All index and delete operations are written to the translog after being processed by the internal Lucene index but before they are acknowledged
> 
> So i am not understanding what this line are saying

could you please explain me what does this line mean ?

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**Author:** ![stephenb](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/stephenb/32/40856_2.png) [@stephenb](https://discuss.elastic.co/u/stephenb)\
**Post date:** [October 22, 2021, 3:09am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374/4 "2021-10-22T03:09:56Z")

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Take a look at this article perhaps it will help.

> **[Guide to Refresh and Flush Operations in Elasticsearch | Qbox HES](https://qbox.io/blog/refresh-flush-operations-elasticsearch-guide/)**
>
> This guide explores subtle differences between Refresh and Flush operations in Elasticsearch showing how the platform takes Lucene approach and radically enhances it.

And this is a good picture...

 ![](https://us1.discourse-cdn.com/elastic/original/3X/6/4/643511047e66de8a4d6bb2991153c6f26e60b937.png)

And this

 ![](https://us1.discourse-cdn.com/elastic/original/3X/5/4/548c46855f2a4e9026d92f5e28acb9f36e42177b.png)

So in short the data is written into memory and structured as segments and then flush to disk once that happens the translog which is also persisted on disk can be cleared and then the process starts over again.

Is there something in particular that's concerning you?

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<div class="post-metadata">

**Author:** ![Aniket\_Pant](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@Aniket\_Pant](https://discuss.elastic.co/u/Aniket_Pant)\
**Post date:** [October 22, 2021, 5:32am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374/5 "2021-10-22T05:32:24Z")

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Thanks @stephenb

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [November 19, 2021, 5:33am UTC](https://discuss.elastic.co/t/clearing-the-concept-of-translog/287374/6 "2021-11-19T05:33:20Z")

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