# Can you give detailed information about documents.json?

**URL:** <https://discuss.elastic.co/t/can-you-give-detailed-information-about-documents-json/164453>\
**Category:** Elasticsearch\
**Tags:** rally\
**Created:** [January 16, 2019, 11:33am UTC](https://discuss.elastic.co/t/can-you-give-detailed-information-about-documents-json/164453 "2019-01-16T11:33:23Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Neslihan](https://avatars.discourse-cdn.com/v4/letter/n/b9e5f3/32.png) [@Neslihan](https://discuss.elastic.co/u/Neslihan)\
**Post date:** [January 16, 2019, 11:33am UTC](https://discuss.elastic.co/t/can-you-give-detailed-information-about-documents-json/164453/1 "2019-01-16T11:33:23Z")

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What is the purpose of the documents.json file when creating custom track?

What is the difference between documents.json with 1gb and documents.json with 10gb when running the benchmark?

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**Author:** ![danielmitterdorfer](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/danielmitterdorfer/32/110510_2.png) [@danielmitterdorfer](https://discuss.elastic.co/u/danielmitterdorfer)\
**Post date:** [January 17, 2019, 6:57am UTC](https://discuss.elastic.co/t/can-you-give-detailed-information-about-documents-json/164453/2 "2019-01-17T06:57:08Z")

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Hi,

please see the [Rally docs](https://esrally.readthedocs.io/en/stable/adding_tracks.html) for full tutorial how to create custom tracks. The file you're mentioning contains the documents that you want to bulk-index to Elasticsearch. It is the document corpus you're operating on in this benchmark and different index sizes cause all sorts of different system behavior, e.g. with larger indices, querying _might_ take longer, page cache behavior might be different (causing less or more load on I/O), you will see different background merge activity in Elasticsearch etc. etc. .

For a general introduction of what to take care of when benchmarking (also from a methodological perspective) I recommend to read the blog post [Seven Tips for Better Elasticsearch Benchmarks](https://www.elastic.co/blog/seven-tips-for-better-elasticsearch-benchmarks).

Daniel

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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:** [February 14, 2019, 7:11am UTC](https://discuss.elastic.co/t/can-you-give-detailed-information-about-documents-json/164453/3 "2019-02-14T07:11:17Z")

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Closed on February 14, 2019, 7:11am UTC

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