jsonb value retrieval performance

[Tom Smith <tomsmith1989sk@xxxxxxxxx>]

Hello:

Does JSONB storage has some internal indexing(like hasmap)

to fast look up a value given a key?

I have a jsonb doc with two level keys

(parentKey: {childKey:value}}

there are maybe 2000 parent keys per doc and 100 child keys per parent key

and I am trying to get value via  jsonb->parentKey->childKey

it seems it is very slow. 

Would it be actually faster to use top level key only and parse it at client side?

Thanks