What's the meaning of 'acceptPartial' and 'backdoorToggles' in Kylin's SQLRequest?

Question

I am studying Kylin, and found when kylin execute a query, there are two param
"acceptPartial" and 'backdoorToggles'. What's the meaning?

public class SQLRequest implements Serializable {
    protected static final long serialVersionUID = 1L;

    private String sql;

    private String project;
    private Integer offset = 0;
    private Integer limit = 0;
    private boolean acceptPartial = false;

    private Map<String, String> backdoorToggles;

I've searched a lot and didn't find the answer.

Answer 1

Accept partial is a hint to query engine that partial query result is acceptable and engine should return as quick as possible rather than get the full correct result back. This is useful when user just want to try out a query, get a few sample lines back and does not need the actual result.

Backdoor toggles are bunch of parameters for debug and troubleshooting purpose. You can come back to them once you are familiar with the basics of Kylin.