core practice · coding problem
Columnar vs row store
Analytics query: SELECT avg(price) FROM sales WHERE date>2024. Which store wins and why?
The mechanism
A column store groups data by column instead of by row. Reading one column out of many becomes very fast (great for analytics), but writing or updating a single row gets slower. Pick row-stores for transactions, column-stores for analytics.
Expected evidence
Columnar — reads only price+date columns, better compression.
Try this drill in the practice workspace →
Hints when you need them
- Row store reads whole records.
- Columnar skips untouched fields.