MariaDB (mySQL) - how to quickly (!) leave only unique options?

Question

css

The question is more general than specific.
In response to the request, we get the answer: It is
1,2,5,8,1,2,2,4,3,5,7
necessary to get only unique (non-repeating) values ​​- this:
1,2,5,8,4,3,7
Usually they use it for this SELECT DISTINCTor GROUP BYif the first one is impossible.
The problem is that the request without SELECT DISTINCTis completed in about 4 minutes (the database is large - this is quite acceptable.) The
request with SELECT DISTINCT- has already been executed for about half an hour, which is a very long time.
How to effectively solve such problems?

Answer 1

grids (display: grid and properties to describe grids) allow you to set this.
With the help of grids, at the level of the parent block, you can specify the standard width/height of the grid cell (both in fractions of the screen, and in pixels, as a percentage, alternating between different options), and already for a particular block, indicate the boundaries of its beginning/end vertically and horizontal lines, based on the grid described in the parent block (for example, specify that the first block goes from line 1 to line 3 in height, and in width - from line 1 to line 2, etc.). You can even specify in the description of the parent block which cells should be occupied by children, indicating their class (example here: https://developer.mozilla.org/en-US/docs/Web/CSS/C... )
Read more about grids at Russian here:https://developer.mozilla.org/en/docs/Web/CSS/CSS_...

Answer 2

Write your own solution and you will be corrected/directed.

Answer 3

It helped to use instead of DISTINCT
GROUP_BY+ an index on the column on which it is executed.
Exploding - personal thanks!

Answer 4

No way.
To execute DISTINCT, sorting is needed - and this is a long time.
As an option - general optimization.
Look at the EXPLAIN PLAN to see what is going wrong with you, which is taking too long.

Answer 5

sort in the database, remove duplicates by code