v26.2 Changelog for Cloud

- Always replaced file names with hashes in MergeTree if the filesystem is case insensitive. Previously on macOS it could lead to data corruption when column/subcolumn names differed only in case. [#86559](https://github.com/ClickHouse/ClickHouse/pull/86559) ([Pavel Kruglov](https://github.com/Avogar)).
- Materialized views now use the database where they were created as execution context, allowing omission of explicit database qualification in the view's select query. [#88193](https://github.com/ClickHouse/ClickHouse/pull/88193) ([Dmitry Kovalev](https://github.com/dk-github)).
- Added full permissions check on the create stage for the underlying query inside a materialized view. [#89180](https://github.com/ClickHouse/ClickHouse/pull/89180) ([pufit](https://github.com/pufit)).
- Fixed logical error when mutation without transaction mutated parts in an active transaction that was rolled back. [#90469](https://github.com/ClickHouse/ClickHouse/pull/90469) ([Shaohua Wang](https://github.com/tiandiwonder)).
- Fixed `system.warnings` not updating correctly after an ordinary database was converted to an atomic database. [#90473](https://github.com/ClickHouse/ClickHouse/pull/90473) ([sdk2](https://github.com/sdk2)).
- Fixed `LOGICAL_ERROR: Storage does not support transaction` during `ATTACH AS REPLICATED`. [#91772](https://github.com/ClickHouse/ClickHouse/pull/91772) ([Shaohua Wang](https://github.com/tiandiwonder)).
- Fixed possible `FILE_DOESNT_EXIST` error after mutation of a sparse column with `ratio_of_defaults_for_sparse_serialization=0.0`. [#92860](https://github.com/ClickHouse/ClickHouse/pull/92860) ([Pavel Kruglov](https://github.com/Avogar)).
- Fixed possible `FILE_DOESNT_EXIST` error after sparse column mutation when `ratio_of_defaults_for_sparse_serialization` was changed to `1.0` via alter. [#93016](https://github.com/ClickHouse/ClickHouse/pull/93016) ([Pavel Kruglov](https://github.com/Avogar)).
- Fixed possible usage of outdated parts due to TOCTOU race for shared parts. [#93022](https://github.com/ClickHouse/ClickHouse/pull/93022) ([Azat Khuzhin](https://github.com/azat)).
- Inherited source part serialization info settings during mutation in MergeTree, fixing possible incorrect query results over mutated parts after data type serialization changes. [#92419](https://github.com/ClickHouse/ClickHouse/pull/92419) ([Pavel Kruglov](https://github.com/Avogar)).
- Fixed possible conflict between column and subcolumn with the same name leading to wrong serialization and query failures. [#92453](https://github.com/ClickHouse/ClickHouse/pull/92453) ([Pavel Kruglov](https://github.com/Avogar)).
- Fixed `NOT_FOUND_COLUMN_IN_BLOCK` during insert into a table with subcolumn in partition expression. [#92905](https://github.com/ClickHouse/ClickHouse/pull/92905) ([Pavel Kruglov](https://github.com/Avogar)).
- Fixed possible missing subcolumn in MV during alter of source table. [#93276](https://github.com/ClickHouse/ClickHouse/pull/93276) ([Pavel Kruglov](https://github.com/Avogar)).
- Fixed `LOGICAL_ERROR` when restoring `ReplicatedMergeTree` with deduplication race. [#93612](https://github.com/ClickHouse/ClickHouse/pull/93612) ([Pablo Marcos](https://github.com/pamarcos)).
- Fixed using sparse column for TTL update during direct deserialization, preventing `Unexpected type of result TTL column` error. [#93619](https://github.com/ClickHouse/ClickHouse/pull/93619) ([Pavel Kruglov](https://github.com/Avogar)).
- Restored `LowCardinality` wrappers on SET expression results if needed during TTL aggregation. [#92971](https://github.com/ClickHouse/ClickHouse/pull/92971) ([Seva Potapov](https://github.com/seva-potapov)).
- Fixed `Cannot add action to empty ExpressionActionsChain` for `ALTER TABLE REWRITE PARTS`. [#92754](https://github.com/ClickHouse/ClickHouse/pull/92754) ([Azat Khuzhin](https://github.com/azat)).
- Fixed query parameter substitution in `CREATE USER` authentication methods when using `ON CLUSTER`. [#92777](https://github.com/ClickHouse/ClickHouse/pull/92777) ([xiaohuanlin](https://github.com/xiaohuanlin)).
- No longer attempts to delete temporary directories at startup if a MergeTree table is on a read-only disk. [#92748](https://github.com/ClickHouse/ClickHouse/pull/92748) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fixed materialization of skip indexes created on top of subcolumns. [#93708](https://github.com/ClickHouse/ClickHouse/pull/93708) ([Anton Popov](https://github.com/CurtizJ)).
- Fixed `CLEAR COLUMN` with dependent indices. [#94057](https://github.com/ClickHouse/ClickHouse/pull/94057) ([Raúl Marín](https://github.com/Algunenano)).
- Fixed attaching Replicated databases when the interserver host changed after restarting. [#93779](https://github.com/ClickHouse/ClickHouse/pull/93779) ([Tuan Pham Anh](https://github.com/tuanpach)).
- Fixed logical error with `CREATE TABLE ... AS urlCluster()` and `Replicated` database engine. [#92418](https://github.com/ClickHouse/ClickHouse/pull/92418) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Fixed race condition between `REPLACE PARTITION` and background mutations that could result in both old and new data being visible. [#96955](https://github.com/ClickHouse/ClickHouse/pull/96955) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fixed remaining race condition between `REPLACE PARTITION` and background mutations that could cause old data to reappear. [#97105](https://github.com/ClickHouse/ClickHouse/pull/97105) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fixed stuck mutations when `PartCheckThread` re-enqueued a `GET_PART` for an already-mutated part. [#97162](https://github.com/ClickHouse/ClickHouse/pull/97162) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fixed `ALTER TABLE DROP COLUMN` failing after a lightweight update was previously performed on the same column. [#96861](https://github.com/ClickHouse/ClickHouse/pull/96861) ([Anton Popov](https://github.com/CurtizJ)).
- Fixed null pointer dereference when applying patch parts during lightweight updates. [#97583](https://github.com/ClickHouse/ClickHouse/pull/97583) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Parts with unknown projections are no longer marked as lost forever. [#95952](https://github.com/ClickHouse/ClickHouse/pull/95952) ([Mikhail Artemenko](https://github.com/Michicosun)).
- Fixed `CREATE TABLE ... CLONE AS ...` ignoring the full qualifier of the source table. [#96415](https://github.com/ClickHouse/ClickHouse/pull/96415) ([Hasyimi Bahrudin](https://github.com/hasyimibhar)).
- Fixed implicit index regeneration in replicated tables during metadata changes. [#96600](https://github.com/ClickHouse/ClickHouse/pull/96600) ([Raúl Marín](https://github.com/Algunenano)).
- Fixed implicit indices with alias columns and added full validation before creating them. [#97115](https://github.com/ClickHouse/ClickHouse/pull/97115) ([Raúl Marín](https://github.com/Algunenano)).
- Fixed `min(timestamp)` returning epoch (`1970-01-01`) via `_minmax_count_projection` after TTL merge when all rows were filtered out. [#96703](https://github.com/ClickHouse/ClickHouse/pull/96703) ([Raquel Barbadillo](https://github.com/rbarbadillo)).
- Fixed combination of `use_const_adaptive_granularity` and `index_granularity_bytes` (non-adaptive granularity) leading to miscalculation. [#96143](https://github.com/ClickHouse/ClickHouse/pull/96143) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fixed `Number of rows in lazy chunk does not match number of offsets` exception when reading from tables with non-adaptive index granularity using `ORDER BY ... LIMIT`. [#97270](https://github.com/ClickHouse/ClickHouse/pull/97270) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fixed regression in zero-copy replication where shared parts could be deleted before other replicas finished fetching them. [#95597](https://github.com/ClickHouse/ClickHouse/pull/95597) ([filimonov](https://github.com/filimonov)).