# Merge 3 CSV files based on common column **URL:** \ **Category:** Elasticsearch\ **Created:** [September 15, 2018, 10:07am UTC](https://discuss.elastic.co/t/merge-3-csv-files-based-on-common-column/148696 "2018-09-15T10:07:14Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![ravi\_yadav1](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@ravi\_yadav1](https://discuss.elastic.co/u/ravi_yadav1)\ **Post date:** [September 15, 2018, 10:07am UTC](https://discuss.elastic.co/t/merge-3-csv-files-based-on-common-column/148696/1 "2018-09-15T10:07:14Z")
Hi, I am trying to merge 3 csv files which have columns like: 1st CSV: [oid, symbol, price, qty, side, err1] 2nd CSV: [oid, tid, symbol, price, qty, side, err2, error\_msg] 3rd CSV: [tid, symbol, price, qty, side, err3] Now as you can see, i have to map oid of 1st csv with tid of 2nd csv and also tid of 3rd csv with oid of 2nd csv. I think it is very similar to outer join queries in relational databases. So what is approach should I follow for such kind of relationships between log files? PS: I have already read many FAQs related to this and tried using Aggregation, Parent-child relationship, but no help ☹ ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [September 15, 2018, 10:33am UTC](https://discuss.elastic.co/t/merge-3-csv-files-based-on-common-column/148696/2 "2018-09-15T10:33:39Z")
You cannot do this in Elasticsearch, you need to do it during ingestion using something like Logstash. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [October 13, 2018, 10:33am UTC](https://discuss.elastic.co/t/merge-3-csv-files-based-on-common-column/148696/3 "2018-10-13T10:33:40Z")
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