# A question about the confluence of rivers **URL:** \ **Category:** Elasticsearch\ **Created:** [April 12, 2012, 8:07am UTC](https://discuss.elastic.co/t/a-question-about-the-confluence-of-rivers/7304 "2012-04-12T08:07:17Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![benny\_sadeh](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/benny_sadeh/32/2797_2.png) [@benny\_sadeh](https://discuss.elastic.co/u/benny_sadeh)\ **Post date:** [April 12, 2012, 8:07am UTC](https://discuss.elastic.co/t/a-question-about-the-confluence-of-rivers/7304/1 "2012-04-12T08:07:17Z")
my understanding is that when you define/create a river (such as the rabbitmq river), you define an index it flows into. my questions are: - can two rivers flow into one index? - can a river flow into an existing index? - the implied question is whether the same index can be fed both by a river and a normal indexing api call and since we are on the subject of rivers, is there a hook for a river to preprocess an entry _before_ it is being index (river -\> [process-or-filter] -\> index) ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [April 13, 2012, 12:16pm UTC](https://discuss.elastic.co/t/a-question-about-the-confluence-of-rivers/7304/2 "2012-04-13T12:16:34Z")
On Thu, Apr 12, 2012 at 11:07 AM, Benny Sadeh [benny.sadeh@gmail.com](mailto:benny.sadeh@gmail.com) wrote: > my understanding is that when you define/create a river (such as the > rabbitmq river), you define an index it flows into. > my questions are: > > - can two rivers flow into one index? > > Yes, they simply perform index operations against that index. > - can a river flow into an existing index? > > Yep. > - the implied question is whether the same index can be fed both by a > river and a normal indexing api call > > Yep. > and since we are on the subject of rivers, is there a hook for a river > to preprocess an entry _before_ it is being index (river -\> > [process-or-filter] -\> index) There is some support for it in certain rivers, the rabbitmq does not as it assumes the message that you send is already processed. ---
**Author:** ![benny\_sadeh](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/benny_sadeh/32/2797_2.png) [@benny\_sadeh](https://discuss.elastic.co/u/benny_sadeh)\ **Post date:** [April 14, 2012, 5:47am UTC](https://discuss.elastic.co/t/a-question-about-the-confluence-of-rivers/7304/3 "2012-04-14T05:47:25Z")
thanks for answering Shay; you're always very responsive, and I appreciate that 🙂 On Apr 13, 5:16 am, Shay Banon [kim...@gmail.com](mailto:kim...@gmail.com) wrote: > On Thu, Apr 12, 2012 at 11:07 AM, Benny Sadeh [benny.sa...@gmail.com](mailto:benny.sa...@gmail.com) wrote: > > > my understanding is that when you define/create a river (such as the > > rabbitmq river), you define an index it flows into. > > my questions are: > > > - can two rivers flow into one index? > > > Yes, they simply perform index operations against that index. > > > - can a river flow into an existing index? > > > Yep. > > > - the implied question is whether the same index can be fed both by a > > river and a normal indexing api call > > > Yep. great, but how? for example, assuming I created an index such as: curl -XPUT [http://localhost:9200/](http://localhost:9200/)/ -d '{ ... then when creating a rabbitmq river, if I would specify: curl -XPUT 'localhost:9200/\_river//\_meta' -d '{ "type" : "rabbitmq", "rabbitmq" : { ... }, "index" : { ... } }' I was assuming this would be a different index: \_river/ rather the am I wrong and this would be one and the same index? > > and since we are on the subject of rivers, is there a hook for a river > > to preprocess an entry _before_ it is being index (river -\> > > [process-or-filter] -\> index) > > There is some support for it in certain rivers, the rabbitmq does not as it > assumes the message that you send is already processed. so I assume if one wanted such [process-or-filter] river functionality, one could just fork the river implementation and change it to do so. I was just wondering if there is a "hook" method to do so, or an agreed/by-convention way. since I haven't looked into how to implement a river docs yet, if the answer is in there, please tell me if I should just rtfm 😉 ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 3:32am UTC](https://discuss.elastic.co/t/a-question-about-the-confluence-of-rivers/7304/4 "2017-07-06T03:32:36Z")
Closed on July 6, 2017, 3:32am UTC