Can I combine result sets in Solr - solr

Question

I want to do the following:
Let A be the set of documents, each with the field important:true, and with a date beginning with this year, or previous year. The result set should be ordered by date. In pseudo code:
Result set A:
q="testquery" +important:true AND +(date:2015* OR date:2016*)
sort=date desc
Then, let B be the remaining set of documents, i.e. those with important:true and a date preceeding year 2015, and also all documents with important:false. This set should also be ordered by date. Again in very sloppy pseudo:
Result set B:
q="testquery" -(date:2015* OR date:2016*)
sort=date desc
Now, i would like to return A followed by B, and be able to use the paging features etc. I am very noob with SOLR ( < 10 hrs of trying out different queries) and I can't figure how to accomplish this behavior. I guess I cannot use bq since we don't sort by score, right?
An example of the desired outcome:
<result name="response" numFound="2089" start="0">
<doc>
<bool name="important">true</bool>
<str name="date">2016-03-01 00:00:00</str>
</doc>
<doc>
<bool name="important">true</bool>
<str name="date">2015-12-01 00:00:00</str>
</doc>
<doc>
<bool name="important">true</bool>
<str name="date">2015-04-01 00:00:00</str>
</doc>
<doc>
<bool name="important">true</bool>
<str name="date">2015-01-01 00:00:00</str>
</doc>
<doc>
<bool name="important">false</bool>
<str name="date">2016-10-01 00:00:00</str>
</doc>
<doc>
<bool name="important">false</bool>
<str name="date">2015-03-01 00:00:00</str>
</doc>
<doc>
<bool name="important">false</bool>
<str name="date">2014-02-01 00:00:00</str>
</doc>
<doc>
<bool name="important">true</bool>
<str name="date">2014-09-01 00:00:00</str>
</doc>
<doc>
<bool name="important">false</bool>
<str name="date">2013-05-01 00:00:00</str>
</doc>
<doc>
<str name="date">2012-09-01 00:00:00</str>
</doc>
</result>
</response>
Notice in the example above that for documents older than 2015, the documents marked important is no more important than any other, they will appear in strict chronological order.
Any help is appreciated, but I would especially love examples using SolrNet syntax :)
EDIT:
I can not make any changes to index or schema...

Answer 1

((important: true AND (date:2016* OR date:2015*))^1001 OR (important: false AND (date:2016* OR date:2015*))^1000 OR date:*) AND something:"foo" and sort score desc, date desc
This will show recent important items first, then recent non-important items, and finally all items, and everything sorted by date in their 'sections'.
something:"foo" at the end of the clause refers to any extra clauses you might have.

Answer 2

The main challenge here - I feel - is sorting by date. Without that, you could easily boost your special privilege query to be at the front. But sorting by date afterwords would reset this and you would be back where you started.
It is possible however to sort by several fields. So, if your special condition could be encoded as a field value during indexing, you could sort by that first, then by date.
If that's not possible to do during the indexing, you may need to add a second trick. It is possible to sort by a function query instead of a field. So, you would need to build a function query expression (probably using if and ms at least) that represents your boost condition.
You may have some challenges representing your 2015/2016 as a condition. If it is a date, you may be able to use date math to create a consistent round-down to a year (NOW/YEAR).
I would start by doing a simpler problem of just pushing the important item to the top, still sorted by date. Just to test that my logic here works. If/once that works with functions and sort and paging, the special dates can be added into the calculation.