๐ Row-oriented
Each record is stored together, side by side.
โ cell reads
Data read from storage
๐๏ธ Row vs. Column Storage Lab
The same table can be stored in different ways. Edit a few records, choose which columns to ask for, and see what a simple SELECT query needs to read in row-oriented and column-oriented storage.
| Row | id | name | department | salary | Actions |
|---|
2 ยท Write a SELECT query
Supports SELECT * or a comma-separated list of columns from employees, with an optional equality filter such as WHERE department = 'Design' or WHERE salary = 90000. Column names are id, name, department, and salary.
3 ยท Compare the reads
Cells read to answer this queryโ
๐ Column-oriented
Values from the same column are stored together.
โ cell reads
Data read from storage
Query result
What counts as a read?
This lab counts individual table cells accessed, not disk pages or bytes. For the row-oriented model, all columns in every row are read to find matching records and return the requested values. For the column-oriented model, an optional filter reads that column for every row, then reads requested columns only for matching rows. A filter column already read is not counted twice. Real database engines use indexes, compression, caching, and storage pages, so their physical I/O can differ.