# Secondary Index - Additional data storage

**URL:** <https://discuss.aerospike.com/t/secondary-index-additional-data-storage/7928>\
**Category:** General Discussion\
**Created:** [October 15, 2020, 1:06am UTC](https://discuss.aerospike.com/t/secondary-index-additional-data-storage/7928 "2020-10-15T01:06:31Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![gtgoudar](https://avatars.discourse-cdn.com/v4/letter/g/4da419/32.png) [@gtgoudar](https://discuss.aerospike.com/u/gtgoudar)\
**Post date:** [October 15, 2020, 1:06am UTC](https://discuss.aerospike.com/t/secondary-index-additional-data-storage/7928/1 "2020-10-15T01:06:31Z")

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Does adding a secondary index (or multiple secondary index) duplicate data or increase the disk space in any way?

In the use case I am talking, the bins store the value as blobs and hence I am not sure how secondary index work in this case.

Thanks

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**Author:** ![Albot](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/albot/32/2076_2.png) [@Albot](https://discuss.aerospike.com/u/Albot)\
**Post date:** [October 17, 2020, 12:57am UTC](https://discuss.aerospike.com/t/secondary-index-additional-data-storage/7928/2 "2020-10-17T00:57:00Z")

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It stores extra references to those keys in memory. [https://www.aerospike.com/docs/operations/plan/capacity/index.html#capacity-planning-for-secondary-indexes](https://www.aerospike.com/docs/operations/plan/capacity/index.html#capacity-planning-for-secondary-indexes)

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**Author:** ![meher](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/meher/32/1644_2.png) [@meher](https://discuss.aerospike.com/u/meher)\
**Post date:** [October 20, 2020, 3:22am UTC](https://discuss.aerospike.com/t/secondary-index-additional-data-storage/7928/3 "2020-10-20T03:22:04Z")

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Having values stored as blobs may not make sense to be then indexed… Secondary indices require String or Numerical or GeoJson.

BTW, the secondary index sub-system is on deck for a re-write… hopefully early next year, which will make it more efficient (memory wise) and more performant!

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**Author:** ![system](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/system/32/2274_2.png) [@system](https://discuss.aerospike.com/u/system)\
**Post date:** [October 20, 2021, 3:22am UTC](https://discuss.aerospike.com/t/secondary-index-additional-data-storage/7928/4 "2021-10-20T03:22:10Z")

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