ClickHouse/clickhouse-connect v1.0.0rc2

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Release Candidate 1.0.0 (rc2)

This is a release candidate for clickhouse-connect 1.0.0. Please test thoroughly with your workloads and report any issues before the final release.

Installation:

pip install clickhouse-connect==1.0.0rc2

If upgrading from 0.15.x, see the migration notes in rc1. All 1.0 breaking changes were introduced there. rc2 contains no new breaking changes.

Highlights

rc2 is primarily a performance release. There is order-of-magnitude faster DateTime/DateTime64 reads, Decimal reads, and fixed-width numpy inserts, plus significantly faster Map reads and writes.

What's Changed

Improvements

• Order-of-magnitude faster DateTime and DateTime64 reads for naive UTC and UTC-equivalent timezones. The Cython read paths now decode via epoch arithmetic and construct datetime objects directly via the CPython datetime C API, bypassing datetime.fromtimestamp and the Python-level datetime(...) constructor. Also fixes Cython DateTime conversion bugs and expands epoch-arithmetic test coverage.
• Significantly faster Map reads and writes. The read path avoids materializing an intermediate pair tuple. The write path moves into a new Cython build_map_columns helper.
• Order-of-magnitude faster fixed-width numeric inserts from numpy arrays, with significantly lower peak memory. A new Cython write_native_col helper writes 1-D C-contiguous numpy arrays of matching dtype directly into the output buffer via memcpy, avoiding the per-element conversion the previous path required.
• Significantly faster Decimal and BigDecimal reads. The decode path no longer constructs intermediate strings per row, building values directly from the integer column via Decimal.scaleb.

Bug Fixes

• Async client: retry once when a pooled keep-alive connection is closed by the server and aiohttp raises ServerDisconnectedError with the default "Server disconnected" message. The existing retry path covered "Connection reset" and "Remote end closed", but not the bare ServerDisconnectedError() produced by recent aiohttp versions, which surfaced as an OperationalError("Network Error: Server disconnected") on the first request after an idle period.
• SQLAlchemy Bool type now accepts and forwards **kwargs to the underlying SqlaBoolean constructor. SQLAlchemy's SchemaType machinery passes internal kwargs (e.g., _create_events) when copying or adapting the type during ORM model use or Table.to_metadata(), which previously raised a TypeError. Fixes #705
• SQLAlchemy: CreateDatabase with engine="Replicated" now emits a closing ) after the (zoo_path, shard, replica) arguments, fixing previously invalid DDL on this path. The same arguments and the system.tables lookup in get_engine now go through bound parameters and the existing format_str helper instead of raw f-string interpolation.