SQL for large scale datasets

Some job descriptions include sth such as "demonstrated skill on handling large scale(massive) datasets using SQL"

I would like to know which kinds of SQL-related skill sets are required for meeting the requirements开发者_开发知识库 of these jobs?

Designing a performant schema and knowing when to denormalize (and when you've got problems you can solve other ways.)

Efficient query design.

The intimate details of index design, to the point where you can make changes and get the results you expected.

How to build, support, and effectively make use of test data.

How to read all the breadcrumbs your server leaves in its trail (logs and query plan analyses in particular.)

How to tell how hardware, dbms software, and configuration work together and be able to adjust parameters and modify hardware without fear, and get the results you expected.

Everything related to SQL would be, IMO. Everything from query writing to DBA changes with large scale datasets.