Limiting query to certain amount of rows evenly distributed Given a table:

id
--
1
2
4
6
8
10


I would like to be able to specify a limit and have that amount of rows returned evenly distributed across the entire set when it is ordered by a specific criteria. For example, 3 rows when the set is ordered by id would give me:

id
--
1
4
10


In the above scenario, either 4 or 6 could have been returned as the middle row. I am not specifically bothered as to which way the selection is rounded.

Ideally I'd like to do this in the most efficient way i.e. the entire table isn't parsed initially.

I found an excellent post here Select every n-th row, don&#39;t pull the entire table, regarding evenly distributed data sets but struggled when trying to calculate n in order to limit the final data set to a specific amount.

I'm currently running MySQL 5.6 on Ubuntu.


Ids are non sequential.
This database is dynamic so I can't hardcode the amount of rows or have select statements that reflect errors in a particular set of results.
You have a dynamic number of rows in the table, and want a specific number of evenly distributed results each time?

I'm asking because the solution you linked is already nearly there: 

   SELECT * 
FROM ( 
    SELECT 
        @row := @row +1 AS rownum, [column name] 
    FROM ( 
        SELECT @row :=0) r, [table name] 
    ) ranked 
WHERE rownum % [n] = 1 


Just replace [n] with the following:

(CEIL(@row/[m]))


where [m] is the number of results you want to have returned.