What is "data push"?

Data push is a feature which sends feed data to an external system via HTTP(S) POST or PUT request, similar to a "web hook". It is sent in the same format and shape as the "GET" feed. Please note that the target application must be able to receive such requests from the Internet and interpret them. Query Feed provides data in a number of generic and widely-supported formats, but it may still be necessary to transform it for use with some applications.

See also Data Push documentation.

How frequently are the feeds refreshed?

It typically takes up to 5 minutes for a change in Jira to be reflected in query feeds.

Does Query Feed include historical data such as work logs?

No. Query Feed only exports current data. Historical records would not be well represented in a tabular or key-value format.