I’m using Flexmonster to connect to my local elasticsearch indices, but would like to know how that happens. In particular I don’t understand how it can load all the data and not the first 10k records as an usual “http://localhost:9200/index/_search?size=10000” would work.

When I run a query (a simple count on a field just to know how many records it reads) there are two network requests:

Both of them use URL: “http://localhost:9200/jolanda_map/_search” and retrive all the dataset because the query shows me the exact number of records (2.7 millions). So:

• Why if I use that same URL i just get the first 10 records?
• Why there are two requests (one with “OPTIONS” method, and one with “POST” method)?
• If I would replicate what Fleximonster does, getting all record in my dataset (rather than first 10 or 10k), how could I do?