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Relevant changes for ClickHouse Cloud services based on the v24.12 release.

## Backward incompatible changes[​](#backward-incompatible-changes "Direct link to Backward incompatible changes")

- Functions `greatest` and `least` now ignore NULL input values, whereas they previously returned NULL if one of the arguments was NULL. For example, `SELECT greatest(1, 2, NULL)` now returns 2. This makes the behavior compatible with PostgreSQL. [#65519](https://github.com/ClickHouse/ClickHouse/pull/65519) ([kevinyhzou](https://github.com/KevinyhZou)).
- Don't allow Variant/Dynamic types in ORDER BY/GROUP BY/PARTITION BY/PRIMARY KEY by default because it may lead to unexpected results. [#69731](https://github.com/ClickHouse/ClickHouse/pull/69731) ([Pavel Kruglov](https://github.com/Avogar)).
- Remove system tables `generate_series` and `generateSeries`. They were added by mistake here: [#59390](https://github.com/ClickHouse/ClickHouse/issues/59390). [#71091](https://github.com/ClickHouse/ClickHouse/pull/71091) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Remove `StorageExternalDistributed`. Closes [#70600](https://github.com/ClickHouse/ClickHouse/issues/70600). [#71176](https://github.com/ClickHouse/ClickHouse/pull/71176) ([flynn](https://github.com/ucasfl)).
- Settings from server config (users.xml) now apply on the client too. Useful for format settings, e.g. `date_time_output_format`. [#71178](https://github.com/ClickHouse/ClickHouse/pull/71178) ([Michael Kolupaev](https://github.com/al13n321)).
- Fix possible error `No such file or directory` due to unescaped special symbols in files for JSON subcolumns. [#71182](https://github.com/ClickHouse/ClickHouse/pull/71182) ([Pavel Kruglov](https://github.com/Avogar)).
- The table engines Kafka, NATS and RabbitMQ are now covered by their own grants in the `SOURCES` hierarchy. Add grants to any non-default database users that create tables with these engine types. [#71250](https://github.com/ClickHouse/ClickHouse/pull/71250) ([Christoph Wurm](https://github.com/cwurm)).
- Check the full mutation query before executing it (including subqueries). This prevents accidentally running an invalid query and building up dead mutations that block valid mutations. [#71300](https://github.com/ClickHouse/ClickHouse/pull/71300) ([Christoph Wurm](https://github.com/cwurm)).
- Rename filesystem cache setting `skip_download_if_exceeds_query_cache` to `filesystem_cache_skip_download_if_exceeds_per_query_cache_write_limit`. [#71578](https://github.com/ClickHouse/ClickHouse/pull/71578) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Forbid Dynamic/Variant types in min/max functions to avoid confusion. [#71761](https://github.com/ClickHouse/ClickHouse/pull/71761) ([Pavel Kruglov](https://github.com/Avogar)).
- Remove support for `Enum` as well as `UInt128` and `UInt256` arguments in `deltaSumTimestamp`. Remove support for `Int8`, `UInt8`, `Int16`, and `UInt16` of the second ("timestamp") argument of `deltaSumTimestamp`. [#71790](https://github.com/ClickHouse/ClickHouse/pull/71790) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Added source query validation when ClickHouse is used as a source for a dictionary. [#72548](https://github.com/ClickHouse/ClickHouse/pull/72548) ([Alexey Katsman](https://github.com/alexkats)).

## New features[​](#new-features "Direct link to New features")