# Logstash join two csv files, one to many data
**URL:** https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019
**Category:** Logstash
**Created:** [July 31, 2019, 2:52am UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019 "2019-07-31T02:52:12Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@genice\_ladroma](https://discuss.elastic.co/u/genice_ladroma)
#### Post date: [July 31, 2019, 2:52am UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/1 "2019-07-31T02:52:12Z")
**Hi,**
**I was able to follow instructions on joining 2 csv files from this link**
> [@Logstash - how to configure CSV filter for joining 2 CSV files based on a common field and send the joined log to ES](https://discuss.elastic.co/t/logstash-how-to-configure-csv-filter-for-joining-2-csv-files-based-on-a-common-field-and-send-the-joined-log-to-es/167125/4):
>
> translate { destination =\> "[@metadata][lookup]" dictionary\_path =\> "/home/user/foo.csv" field =\> "COMMIT\_SHA1" } dissect { mapping =\> { "[@metadata][lookup]" =\> "%{FILE\_CHANGED};%{FILE\_TYPE};%{FILE\_METHOD}" } }
**However, this is just for joining one to one data, e.g.**
_file1.csv_
_id,name_
_1,john_
_2,jonathan_
_file2.csv_
_id,lastname_
_1,wick_
_2,smith_
**this results to**
_1,john,wick_
_2,jonathan,smith_
**I would like to know if there's a way we join 2 csv file with one to many data, e.g.**
_file1.csv_
_id,name_
_1,john_
_2,jonathan_
_file2.csv_
_id,lastname_
_1,wick_
_1,summers_
_2,smith_
_2,winters_
**which will result to**
_1,john,wick_
_1,john,summers_
_2, jonathan, smith_
_2, jonathan, winters_
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [July 31, 2019, 1:19pm UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/2 "2019-07-31T13:19:23Z")
Use file1.csv as the dictionary in a translate filter. logstash does not care that there are many events that lookup the same entry.
---
### Author:  [@James\_Daily](https://discuss.elastic.co/u/James_Daily)
#### Post date: [August 9, 2019, 1:48am UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/3 "2019-08-09T01:48:15Z")
Can an id ever have two entries in file1, eg:
1 John
1 Jerry
2 Alice
?
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [August 9, 2019, 12:23pm UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/4 "2019-08-09T12:23:22Z")
Under the hood translate is using a hash, so when it loads the file it will not object, but only Jerry will be included in the translation of 1.
---
### Author:  [@James\_Daily](https://discuss.elastic.co/u/James_Daily)
#### Post date: [August 9, 2019, 2:17pm UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/5 "2019-08-09T14:17:20Z")
I meant to direct my question to @genice_ladroma 🙂
If file1 doesn't have unique id's, then the dictionary approach will not work.
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [August 9, 2019, 2:27pm UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/6 "2019-08-09T14:27:29Z")
Agreed, many to many will not work, but one to many should.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [September 6, 2019, 2:27pm UTC](https://discuss.elastic.co/t/logstash-join-two-csv-files-one-to-many-data/193019/7 "2019-09-06T14:27:31Z")
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