What is the right way to snyc/import tables from a postgres DB to elasticsearch?

Question

I want to import some tables from a postgres database into Elastic search and also hold the tables in sync with the data in elastic search. I have looked at a course on udemy, and also talked with a colleague who has a lot of experience with this issue to see what the best way to do it is. I am surprised to hear from both of them, it seems like the best way to do it, is to write code in python, java or some other language that handles this import and sync it which brings me to my question. Is this actually the best way to handle this situation? It seems like there would be a library, plugin, or something that would handle the situation of importing data into elastic search and holding it in sync with an external database. What is the best way to handle this situation?

Answer 1

It depends on your use case. A common practice is to handle this on the application layer. Basically what you do is to replicate the actions of one db to the other. So for example if you save one entry in postgres you do the same in elasticsearch.

If you do this however you'll have to have a queuing system in place. Either the queue is integrated on your application layer, e.g. if the save in elasticsearch fails then you can replay the operation. Moreover on your queuing system you'll implement a throttling mechanism in order to not overwhelm elasticsearch. Another approach would be to send events to another app (e.g. logstash etc), so the throttling and persistence will be handled by that system and not your application.

Another approach would be this https://www.elastic.co/blog/logstash-jdbc-input-plugin. You use another system that "polls" your database and sends the changes to elasticsearch. In this case logstash is ideal since it's part of the ELK stack and it has a great integration. Check this too https://www.elastic.co/guide/en/logstash/current/plugins-inputs-jdbc.html

Another approach is to use the NOTIFY mechanism of postgres to send events to some queue that will handle saving the changes in elasticsearch.