title_wip

#### Experimental feature[​](#experimental-feature-2 "Direct link to Experimental feature")

- Adds a setting `input_format_try_infer_variants` which allows `Variant` type to be inferred during schema inference for text formats when there is more than one possible type for column/array elements. [#63798](https://github.com/ClickHouse/ClickHouse/pull/63798) ([Shaun Struwig](https://github.com/Blargian)).
- Add aggregate functions `distinctDynamicTypes`/`distinctJSONPaths`/`distinctJSONPathsAndTypes` for better introspection of JSON column type content. [#68463](https://github.com/ClickHouse/ClickHouse/pull/68463) ([Kruglov Pavel](https://github.com/Avogar)).
- New algorithm to determine the unit of marks distribution between parallel replicas by a consistent hash. Different numbers of marks chosen for different read patterns to improve performance. [#68424](https://github.com/ClickHouse/ClickHouse/pull/68424) ([Nikita Taranov](https://github.com/nickitat)).
- Previously the algorithmic complexity of part deduplication logic in parallel replica announcement handling was O(n^2) which could take noticeable time for tables with many part (or partitions). This change makes the complexity O(n\*log(n)). [#69596](https://github.com/ClickHouse/ClickHouse/pull/69596) ([Alexander Gololobov](https://github.com/davenger)).
- Refreshable materialized view improvements: append mode (`... REFRESH EVERY 1 MINUTE APPEND ...`) to add rows to existing table instead of overwriting the whole table, retries (disabled by default, configured in SETTINGS section of the query), `SYSTEM WAIT VIEW <name>` query that waits for the currently running refresh, some fixes. [#58934](https://github.com/ClickHouse/ClickHouse/pull/58934) ([Michael Kolupaev](https://github.com/al13n321)).
- Added `min_max`as a new type of (experimental) statistics. It supports estimating range predicates over numeric columns, e.g. `x < 100`. [#67013](https://github.com/ClickHouse/ClickHouse/pull/67013) ([JackyWoo](https://github.com/JackyWoo)).
- Improve castOrDefault from Variant/Dynamic columns so it works when inner types are not convertible at all. [#67150](https://github.com/ClickHouse/ClickHouse/pull/67150) ([Kruglov Pavel](https://github.com/Avogar)).
- Replication of subset of columns is now available through MaterializedPostgreSQL. Closes [#33748](https://github.com/ClickHouse/ClickHouse/issues/33748). [#69092](https://github.com/ClickHouse/ClickHouse/pull/69092) ([Kruglov Kirill](https://github.com/1on)).

#### Performance Improvement[​](#performance-improvement-3 "Direct link to Performance Improvement")

- Implemented reading of required files only for Hive partitioning. [#68963](https://github.com/ClickHouse/ClickHouse/pull/68963) ([Yarik Briukhovetskyi](https://github.com/yariks5s)).
- Improve the JOIN performance by rearranging the right table by keys while the table keys are dense in the LEFT or INNER hash joins. [#60341](https://github.com/ClickHouse/ClickHouse/pull/60341) ([kevinyhzou](https://github.com/KevinyhZou)).
- Improve ALL JOIN performance by appending the list of rows lazily. [#63677](https://github.com/ClickHouse/ClickHouse/pull/63677) ([kevinyhzou](https://github.com/KevinyhZou)).
- Load filesystem cache metadata asynchronously during the boot process, in order to make restarts faster (controlled by setting `load_metadata_asynchronously`). [#65736](https://github.com/ClickHouse/ClickHouse/pull/65736) ([Daniel Pozo Escalona](https://github.com/danipozo)).
- Functions `array` and `map` were optimized to process certain common cases much faster. [#67707](https://github.com/ClickHouse/ClickHouse/pull/67707) ([李扬](https://github.com/taiyang-li)).
- Trivial optimize on ORC strings reading especially when a column contains no NULLs. [#67794](https://github.com/ClickHouse/ClickHouse/pull/67794) ([李扬](https://github.com/taiyang-li)).
- Improved overall performance of merges by reducing the overhead of scheduling steps of merges. [#68016](https://github.com/ClickHouse/ClickHouse/pull/68016) ([Anton Popov](https://github.com/CurtizJ)).
- Speed up requests to S3 when a profile is not set, credentials are not set, and IMDS is not available (for example, when you are querying a public bucket on a machine outside of a cloud). This closes [#52771](https://github.com/ClickHouse/ClickHouse/issues/52771). [#68082](https://github.com/ClickHouse/ClickHouse/pull/68082) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Devirtualize format reader in `RowInputFormatWithNamesAndTypes` for some performance improvement. [#68437](https://github.com/ClickHouse/ClickHouse/pull/68437) ([李扬](https://github.com/taiyang-li)).
- Add the parallel merge for `uniq` aggregate function when aggregating with a group by key to maximize the CPU utilization. [#68441](https://github.com/ClickHouse/ClickHouse/pull/68441) ([Jiebin Sun](https://github.com/jiebinn)).
- Add settings `output_format_orc_dictionary_key_size_threshold` to allow user to enable dict encoding for string column in `ORC` output format. It helps reduce the output `ORC` file size and improve reading performance significantly. [#68591](https://github.com/ClickHouse/ClickHouse/pull/68591) ([李扬](https://github.com/taiyang-li)).
- Introduce new Keeper request RemoveRecursive which removes node with all it's subtree. [#69332](https://github.com/ClickHouse/ClickHouse/pull/69332) ([Mikhail Artemenko](https://github.com/Michicosun)).
- Speedup insertion performance into a table with a vector similarity index by adding data to the vector index in parallel. [#69493](https://github.com/ClickHouse/ClickHouse/pull/69493) ([flynn](https://github.com/ucasfl)).
- Reduce memory usage of inserts to JSON by using adaptive write buffer size. A lot of files created by JSON column in wide part contains small amount of data and it doesn't make sense to allocate 1MB buffer for them. [#69272](https://github.com/ClickHouse/ClickHouse/pull/69272) ([Kruglov Pavel](https://github.com/Avogar)).
- Avoid returning a thread in the concurrent hash join threadpool to avoid query excessively spawn threads. [#69406](https://github.com/ClickHouse/ClickHouse/pull/69406) ([Duc Canh Le](https://github.com/canhld94)).

#### Improvement[​](#improvement-3 "Direct link to Improvement")