Performance impact due to _source storage

If we store the _source so that we can do partial update

Partial Updates to Documents | Elasticsearch: The Definitive Guide [2.x] | Elastic

Other than having a hit on disk space needed to sore the data, do we have any known query scenario where performance will be hit?

Typically storing source is the right way to go but if you frequently
highlight or return small fields (< 100KB) on documents that contain large
fields (> 2MB) you'll start to see decoding the source be a performance hit.

On the other hand this is something that the Elasticsearch team is talking
about working on so I expect that problem will disappear in a while. Its a
bit of a complex issue but its a recognized one.

1 Like

thanks @nik9000

@nik9000 - Looks like I'm running into the issue you explained. My _source is big in size and I'm using nested mapping. I've bunch of fields but I'm interested to retrieve only a few. One of the field to be retrieved is nested field. I tried setting store to true for nested field but looks like I'm running into this issue:

@johtani / @Martijn_van_Groninge - was this issue fixed? []