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Merge pull request #43363 from CamiloSierraH/patch-6

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ATTACH query ignores the SELECT query on MV
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Dan Roscigno 2022-11-23 11:35:15 -05:00 committed by GitHub
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docs/en/sql-reference/statements/create/view.md
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@ -60,7 +60,7 @@ If you specify `POPULATE`, the existing table data is inserted into the view whe
A `SELECT` query can contain `DISTINCT`, `GROUP BY`, `ORDER BY`, `LIMIT`. Note that the corresponding conversions are performed independently on each block of inserted data. For example, if `GROUP BY` is set, data is aggregated during insertion, but only within a single packet of inserted data. The data won’t be further aggregated. The exception is when using an `ENGINE` that independently performs data aggregation, such as `SummingMergeTree`.
The execution of [ALTER](../../../sql-reference/statements/alter/view.md) queries on materialized views has limitations, so they might be inconvenient. If the materialized view uses the construction `TO [db.]name`, you can `DETACH` the view, run `ALTER` for the target table, and then `ATTACH` the previously detached (`DETACH`) view.
The execution of [ALTER](/docs/en/sql-reference/statements/alter/view.md) queries on materialized views has limitations, for example, you can not update the `SELECT` query, so this might be inconvenient. If the materialized view uses the construction `TO [db.]name`, you can `DETACH` the view, run `ALTER` for the target table, and then `ATTACH` the previously detached (`DETACH`) view.
Note that materialized view is influenced by [optimize_on_insert](../../../operations/settings/settings.md#optimize-on-insert) setting. The data is merged before the insertion into a view.