v.22.10Improvement

Support EXPLAIN in Subqueries for ClickHouse

Official CH changelog text
Support expression (EXPLAIN SELECT ...) in a subquery. Queries like SELECT * FROM (EXPLAIN PIPELINE SELECT col FROM TABLE ORDER BY col) became valid. #40630 (Vladimir C).
Support the use of EXPLAIN SELECT ... expressions inside subqueries, allowing queries like SELECT * FROM (EXPLAIN PIPELINE SELECT col FROM TABLE ORDER BY col).

Why it matters

This feature enables users to embed EXPLAIN statements within subqueries, enhancing query introspection and debugging capabilities by allowing pipeline analysis and other explanations to be part of complex query structures.

How to use it

Users can now write queries that include EXPLAIN SELECT ... inside subqueries directly, for example:

SELECT * FROM (EXPLAIN PIPELINE SELECT col FROM TABLE ORDER BY col)

No additional configuration is required to enable this functionality.

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