v.25.12New Feature

Support direct (nested loop) join

Official CH changelog text
Support direct (nested loop) join for MergeTree tables. To use it, specify it as the single option in the setting: join_algorithm = 'direct'. #89920 (Vladimir Cherkasov).
ClickHouse now supports the direct (nested loop) join algorithm for MergeTree tables.

Why it matters

This feature introduces the direct join algorithm which performs nested loop joins, providing an alternative join strategy. It can be useful in scenarios where traditional hash or merge joins are not optimal, potentially improving join performance and flexibility on MergeTree tables.

How to use it

To enable the direct join algorithm, set the setting join_algorithm to 'direct' as the sole option, for example:

SET join_algorithm = 'direct'

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