Problem
I'm building a postgres database for a few hundred thousand products. I will set-up an index (Solr or maybe ElasticSearch) to improve query times for complex search queries.
The point now is how to let the index synchronized with the database?
In the past I had a kind of application that polled the database periodically to check for updates that should be done, but I would have an outdated index state time (from the database update to the index update pull).
I would prefer a solution in which the database would notify my application (java application) that something has been changed within the database, and at that point the application will decide if the index needs to be updated or not. To be more accurate, I would build a kind of producer and consumer structure in wish the replica will receive notifications from postgres that something changed, if this is pertinent to the data indexed it is stored in a stack of updates-to-do. The consumer would consume this stack and build the documents to be stored into the index.
Possible Solutions
One solution would be to write a kind of replica end-point in which the application would behave as a postgres instance that is being used to replicate the data from the original database. Do someone have some experience with this approach?
Which other solution do I have for this problem?