How to sort data from two tables with lots of data?

Question

MySQL

There are two tables with a huge number of posts. 1 - post archive, 2 - current post storage. How to quickly get 20 posts from two given tables, sorting by author, for example.

Answer 1

"Big" is how much? What is the purpose of your current posts and archive together, why archive then? How many posts from each and with what sorting?

Answer 2

to make an index on the author?
"a huge amount" and "quickly" - how much in measurable units?

Answer 3

There are 10k posts in the archive in the current 4k. Indexes are worth.

Answer 4

afaik, no way. If the sort is not by the primary key, then MySQL makes a temporary table, and only then sorts.

Answer 5

How to quickly get 20 posts from two given tables, sorting by author, for example.

Take 20 posts from each table with the desired sorting, manually merge.