I would like to add data into Calc with more than one million rows! How would it be possible? E.g. importing data from database…
I would suggest to add unlimited rows and also columns feature into Calc. There might be a problem also with columns quantity.
If there is not enough columns in Calc then you have serious design problem. You will need to import data into database, but make a good data model first…
Refer this answer. In simple terms (i.e., within a single sheet) this is currently not possible as row limit is ~1m.
The short answer is: it’s not currently possible in Calc.
If you really need a spreadsheet with more than 1 million (2^20) lines , I suggest that you use Gnumeric. You can set up to 16 million (2^24) lines and up to 16384 (=2^14) columns.
Hope this helps 
If you are importing million rows into Calc you got to be doing something wrong… You most probably need a database, so look at LibreOffice Base or some other database out there e.g. MySQL, Postgresql, … there are also free databases from Microsoft, Oracle, IBM etc.
If you still insist to get so many data into spreadsheet, then try to break data down to multiple sheets.
Maybe you can connect with Base to your database and run a view to organize, select and summarizing data for calc, also Pivot Table can use a table or a view from a register database to operate.
What is the data source?