Parallel reading from replicas#29279
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nikitamikhaylov merged 71 commits intoClickHouse:masterfrom Dec 9, 2021
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Ok, just need to disable for |
…el-reading-from-replicas
KochetovNicolai
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@Mergifyio update |
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Internal documentation ticket: DOCSUP-19955 |
This was referenced Mar 14, 2026
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Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
Added an ability to read from all replicas within a shard during distributed query. To enable this, set
allow_experimental_parallel_reading_from_replicas=trueandmax_parallel_replicasto any number. This closes #26748Detailed description / Documentation draft:
We already have such mechanism, but it works only for tables with
SAMPLE BYkey. This feature will work for any kind of MergeTree tables. Ifmax_parallel_replicasis set to some value > 1, then the old algorithm is enabled (backward compatible change).