fix(clickhouse): time filters use server timezone for toDateTime literals by innovark37 · Pull Request #41579 · apache/superset

innovark37 · 2026-06-30T12:21:45Z

SUMMARY

Fixes ClickHouse temporal filter SQL generation for deployments where the ClickHouse server/session timezone is not UTC.

Superset computes time filter bounds in UTC, but ClickHouse toDateTime('YYYY-MM-DD HH:mm:ss') interprets the string in the server/session timezone when no timezone argument is provided. This can shift the effective filter bounds and cause expected rows to be excluded.

This change renders ClickHouse DateTime literals with an explicit UTC timezone:

toDateTime('2026-06-30 09:20:00', 'UTC')

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Setup

ClickHouse configured with a non-UTC timezone (Europe/Moscow)

Test data

Before:

The chart returns an empty result even when the selected UTC time range contains matching rows.

The generated SQL uses toDateTime('...', ) without an explicit timezone:

toDateTime('2026-06-30 09:20:00')

After:

The same chart returns the expected row.

The generated SQL includes the UTC timezone explicitly:

toDateTime('2026-06-30 09:20:00', 'UTC')

TESTING INSTRUCTIONS

Configure ClickHouse with a non-UTC timezone, for example Europe/Moscow.
Verify timezone behavior in SQL Lab:

SELECT
  timezone() AS clickhouse_tz,
  toUnixTimestamp(toDateTime('2026-06-30 09:00:00')) AS without_tz,
  toUnixTimestamp(toDateTime('2026-06-30 09:00:00', 'UTC')) AS with_utc,
  without_tz - with_utc AS diff_seconds;

Create test data:

CREATE DATABASE IF NOT EXISTS tz_bug_test;

DROP TABLE IF EXISTS tz_bug_test.events;

CREATE TABLE tz_bug_test.events
(
  id UInt8,
  name String,
  createdAt DateTime('UTC')
)
ENGINE = MergeTree
ORDER BY createdAt;

INSERT INTO tz_bug_test.events VALUES
  (1, 'event 12:00 Moscow', toDateTime('2026-06-30 09:00:00', 'UTC')),
  (2, 'event 12:30 Moscow', toDateTime('2026-06-30 09:30:00', 'UTC')),
  (3, 'event 13:00 Moscow', toDateTime('2026-06-30 10:00:00', 'UTC'));

Create a dataset for tz_bug_test.events.
Ensure createdAt is marked as temporal.
Create a Table chart with id, name, and createdAt.
Use createdAt as the time column.
Apply this custom time range:

2026-06-30 09:20:00 : 2026-06-30 09:40:00

Confirm that event 12:30 Moscow is returned.
Open the generated SQL and confirm the filter uses:

toDateTime('2026-06-30 09:20:00', 'UTC')

ADDITIONAL INFORMATION

Has associated issue:
Required feature flags:
Changes UI
Includes DB Migration (follow approval process in SIP-59)
- Migration is atomic, supports rollback & is backwards-compatible
- Confirm DB migration upgrade and downgrade tested
- Runtime estimates and downtime expectations provided
Introduces new feature or API
Removes existing feature or API

bito-code-review · 2026-06-30T12:21:56Z

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codecov · 2026-06-30T12:25:45Z

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❌ Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.41%. Comparing base (7cc7e9f) to head (36275c0).

Files with missing lines	Patch %	Lines
superset/db_engine_specs/clickhouse.py	20.00%	4 Missing ⚠️

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@@            Coverage Diff             @@
##           master   #41579      +/-   ##
==========================================
- Coverage   64.42%   64.41%   -0.01%     
==========================================
  Files        2668     2668              
  Lines      147183   147186       +3     
  Branches    33947    33948       +1     
==========================================
- Hits        94822    94817       -5     
- Misses      50646    50652       +6     
- Partials     1715     1717       +2

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bito-code-review · 2026-06-30T15:47:59Z

Code Review Agent Run #683152

Actionable Suggestions - 0

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Files reviewed - 2 · Commit Range: b2bfdbf..21a6992
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rusackas

Thanks @innovark37, pinning the toDateTime literal to 'UTC' is the right call given our filter datetimes are UTC-naive, and normalizing tz-aware inputs first is a nice touch. Your rebuttal on the Top-N/prequery thread reads right to me too... that path already leans on the same UTC-naive convention. LGTM!

fix(clickhouse): add UTC timezone to DateTime literals

b2bfdbf

pull-request-size Bot added the size/M label Jun 30, 2026

dosubot Bot added data:connect:clickhouse Related to Clickhouse explore:filter Related to filters in Explore global:timezone Related to timezones labels Jun 30, 2026

codeant-ai-for-open-source Bot reviewed Jun 30, 2026

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Comment thread superset/db_engine_specs/clickhouse.py Outdated

Comment thread tests/unit_tests/db_engine_specs/test_clickhouse.py Outdated

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Comment thread superset/db_engine_specs/clickhouse.py Outdated

chore(clickhouse): annotate variables

21a6992

sadpandajoe requested review from betodealmeida and mistercrunch June 30, 2026 17:30

innovark37 added 2 commits July 1, 2026 09:35

Merge branch 'master' into innovark/fix/clickhouse-time-filter-utc

dff14d4

Merge branch 'master' into innovark/fix/clickhouse-time-filter-utc

36275c0

rusackas approved these changes Jul 7, 2026

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rusackas merged commit f6d03e4 into apache:master Jul 8, 2026
59 checks passed

innovark37 deleted the innovark/fix/clickhouse-time-filter-utc branch July 13, 2026 05:16

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fix(clickhouse): time filters use server timezone for toDateTime literals#41579

fix(clickhouse): time filters use server timezone for toDateTime literals#41579
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innovark37 commented Jun 30, 2026

SUMMARY

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Setup

Before:

After:

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

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