2025 Changelog

ClickHouse release v25.6.4.12-stable (c3c91c0239e) FIXME as compared to v25.6.3.116-stable (3c68d19c3b3)

Improvement

• Backported in #83635: When distributed_ddl_output_mode='*_only_active', don't wait for new or recovered replicas that have replication lag bigger than max_replication_lag_to_enqueue. This should help to avoid DDL task is not finished on some hosts when a new replica becomes active after finishing initialization or recovery, but it accumulated huge replication log while initializing. Also, implement SYSTEM SYNC DATABASE REPLICA STRICT query that waits for replication log to become below max_replication_lag_to_enqueue. #83302 (Alexander Tokmakov).

Bug Fix (user-visible misbehavior in an official stable release)

• Backported in #83556: Disable bounds-based file pruning for iceberg array element and iceberg map values, including all their nested subfields. #83520 (Daniil Ivanik).
• Backported in #83674: Fix incorrect memory around max_untracked_memory. #83607 (Azat Khuzhin).
• Backported in #83663: INSERT SELECT with UNION ALL could lead to a null pointer dereference in a corner case. This closes #83618. #83643 (Alexey Milovidov).
• Backported in #83745: Fix endless loop in estimateCompressionRatio() with block_size_bytes=0. #83704 (Azat Khuzhin).