ClickHouse Release 26.2

Summary

ClickHouse version 26.2 introduces twenty-five new features, forty-three performance optimizations, and one hundred eighty-three bug fixes across the database engine. This release graduates both the text-index and the QBit vector embedding data type to production-ready status for search and retrieval workloads. For streaming ingestion pipelines where row arrival rates are low, the engine adds time-based block flushing configurations to write data parts before hitting default row or byte thresholds. The update also embeds the ClickStack observability user interface directly into the standard binary distribution, accessible through the local HTTP server port. Further enhancements include automatic min-max indexing for temporal columns in MergeTree tables, interactive time-based one-time password authentication in the client, and a high-performance prime number generator function.

Context

Streaming continuous, low-volume feeds into ClickHouse previously caused data visibility delays due to default block insertion thresholds of 1,000,000 rows or 268 MB. In addition, using the ClickStack observability interface previously required running separate Docker containers or managed infrastructure, and setting up minmax pruning indices on date and time columns required explicit manual table definitions.

Approach / What changed

The release adds input_format_max_block_wait_ms and input_format_connection_handling to flush in-memory blocks by elapsed time, embeds the ClickStack UI directly inside the ClickHouse binary, marks text-index and QBit vector types as production-ready, introduces the add_minmax_index_for_temporal_columns MergeTree setting, and adds TOTP interactive authentication to clickhouse-client.

Takeaways

• Setting input_format_max_block_wait_ms alongside input_format_connection_handling allows low-throughput data streams to flush in-memory blocks at fixed time intervals instead of waiting for size limits.
• The add_minmax_index_for_temporal_columns setting automatically builds compact minmax indices for Date, DateTime, and Time columns to prune granules during range queries and Top-N ordering.
• The clickhouse-client supports interactive two-factor authentication using TOTP secrets configured per user in YAML with SHA1 hashing and thirty-second periods.

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