The big issue with this is permissions. Your query does not take into 
account gallery permissions.  you would need to either join in the 
ansel_shares, as well as user and group tables, or first query for a 
list of galleries to pull images from, then add an IN clause to your 
query.  Either option is potentially very expensive.

That being said, I'm going to mark this as a duplicate of your related 
request Ticket: #8472.

Note that at this point no new functionality will beaded to the 
framework 3 branch.  All new work will be in Ansel 2.

will it be possible to add a calendarical overview? i think of a view 
like the month view in kronolith where i can see on which days photos 
in my galleries (that i can read) are taken. and then when i click on 
a day with photos i can see these photos like in a virtual gallery

i only have a query at this time but maybe you understand what i mean:
SELECT count(*), DATE_FORMAT(FROM_UNIXTIME(ia.attr_value), "%Y-%m-%d") 
as date from ansel_images i inner join ansel_image_attributes ia on 
(i.image_id = ia.image_id) where ia.attr_name = 'DateTimeOriginal' 
group by DATE_FORMAT(FROM_UNIXTIME(ia.attr_value), "%Y-%m-%d")