Let say I have a thousand keys, and I would want to store the associated values. The intuitive approach seems to be something like
{
\"key1\":\"someval\",
Elasticsearch is not ideal for 1000s of key-value pattern in a document. and if you want to update them in real-time or something, then try redis or riak for that.
If you have thousands of keys in a document/record, essentially they become fields and the value become the text and indexed.
From information-retrieval perspective with large data, it is advised to use fewer big fields than numerous small fields, for faster search performance.