ClickHouse·ClickHouse essentials

Queries

Columnar storage makes aggregations fast.

Advanced 10 min read Lesson 3 of 150 Challenge included
What you will be able to do
  • Filter on the sort key.
  • Use count and sum.
  • Limit high-cardinality grouping.

In plain English

Columnar storage makes aggregations fast.

  • Filter on the sort key.
  • Use count and sum.
  • Limit high-cardinality grouping.
query.sqlSQL
SELECT course, sum(minutes) AS total
FROM lessons
GROUP BY course
ORDER BY total DESC;
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Answer from memory: What does columnar storage optimise?

TEXT · starter
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What does columnar storage optimise?

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