PromQL: implement dropping metric name by vitlibar · Pull Request #96741 · ClickHouse/ClickHouse

vitlibar · 2026-02-12T11:40:32Z

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PromQL: implement dropping metric name

Prometheus often drops the metric name after calling a function, for example see.
We should do the same.

Part of #89356

clickhouse-gh · 2026-02-12T11:41:09Z

Workflow [PR], commit [86c4ca8]

Summary: ❌

job_name	test_name	status	info	comment
Stateless tests (amd_ubsan, sequential)		failure
	03206_replication_lag_metric	FAIL	cidb, issue	ISSUE CREATED
Integration tests (amd_asan, targeted)		error		IGNORED

Copilot

Pull request overview

Implements PromQL behavior of dropping the metric name (__name__) in query results and introduces a new time-series aggregate function to coalesce grid values, with accompanying SQL/integration tests and documentation.

Changes:

Add dropMetricName() transformation in PromQL-to-SQL conversion, tracking whether __name__ has already been dropped.
Introduce and register timeSeriesCoalesceGridValues(mode) aggregate function (with docs + stateless tests).
Update Prometheus protocol integration tests to expect dropped metric names and add duplicate-series error coverage.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
tests/queries/0_stateless/03821_time_series_coalesce_grid_values.sql	Adds stateless SQL coverage for `timeSeriesCoalesceGridValues()` modes and group-aware errors.
tests/queries/0_stateless/03821_time_series_coalesce_grid_values.reference	Expected outputs for the new stateless test.
tests/integration/test_prometheus_protocols/test_evaluation.py	Updates expectations for dropped `__name__`, adds multi-series/rate cases and error assertions, improves query helpers.
tests/integration/test_prometheus_protocols/prometheus_test_utils.py	Adds `expect_error` flow to return error bodies for HTTP API calls.
src/Storages/TimeSeries/PrometheusQueryToSQL/dropMetricName.h	Declares `dropMetricName()` helper for PromQL-to-SQL conversion.
src/Storages/TimeSeries/PrometheusQueryToSQL/dropMetricName.cpp	Implements dropping `__name__` by removing the tag and re-coalescing vector grids.
src/Storages/TimeSeries/PrometheusQueryToSQL/applyFunctionOverRange.cpp	Applies `dropMetricName()` for most `_over_time` functions.
src/Storages/TimeSeries/PrometheusQueryToSQL/SQLQueryPiece.h	Adds `metric_name_dropped` flag to avoid dropping `__name__` multiple times.
src/AggregateFunctions/registerAggregateFunctions.cpp	Registers the new time-series aggregate function.
src/AggregateFunctions/TimeSeries/AggregateFunctionTimeSeriesCoalesceGridValues.h	Defines `timeSeriesCoalesceGridValues()` aggregate function implementation.
src/AggregateFunctions/TimeSeries/AggregateFunctionTimeSeriesCoalesceGridValues.cpp	Factory/registration, parameter parsing, and type validation for the aggregate function.
docs/en/sql-reference/aggregate-functions/reference/timeSeriesCoalesceGridValues.md	Adds user documentation for `timeSeriesCoalesceGridValues()`.

src/AggregateFunctions/TimeSeries/AggregateFunctionTimeSeriesCoalesceGridValues.h

src/AggregateFunctions/TimeSeries/AggregateFunctionTimeSeriesCoalesceGridValues.cpp

docs/en/sql-reference/aggregate-functions/reference/timeSeriesCoalesceGridValues.md

tests/integration/test_prometheus_protocols/test_evaluation.py

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

tests/integration/helpers/client.py:305

CommandRequest.get_error() now treats a process exit code 0 as “failed” if stderr is non-empty, and returns stderr instead of raising. This means query_and_get_error() can no longer guarantee the query actually failed (successful queries that emit warnings to stderr will be interpreted as an error), which can hide real regressions in integration tests. Consider keeping the strict returncode == 0 check (always raise) or explicitly detect ClickHouse exception output (e.g. by matching the standard Code: ... DB::Exception prefix) before accepting stderr as an error signal.

        if self.process.returncode == 0 and not self.remove_trash_from_stderr(stderr):
            raise QueryRuntimeException(
                "Client expected to be failed but succeeded! stdout: {}".format(stdout),
                self.process.returncode,
                stderr,
            )

        return stderr

src/Storages/TimeSeries/PrometheusQueryToSQL/dropMetricName.cpp

vitlibar · 2026-02-16T10:18:38Z

Ready for review

vitlibar · 2026-02-16T13:04:36Z

src/Storages/TimeSeries/PrometheusQueryToSQL/dropMetricName.cpp

+        }
+
+        case StoreMethod::VECTOR_GRID:
+        {


Here is some explanation about this new function timeSeriesThrowDuplicateSeriesIf()

vitlibar · 2026-02-16T13:06:15Z

tests/integration/test_prometheus_protocols/test_evaluation.py

-        # | E     - {"resultType": "matrix", "result": [{"metric": {}, "values": [[120, "0"], [135, "0.2"], [150, "0.1"], [165, "0.1"], [210, "0.3"]]}]}
-        # | E     + {"resultType": "matrix", "result": [{"metric": {"__name__": "test"}, "values": [[120, "0"], [135, "0.2"], [150, "0.1"], [165, "0.1"], [210, "0.3"]]}]}
-        # | E     ?                                                 ++++++++++++++++++
-        False,


With dropping of the metric name some tests give the expected results now.

clickhouse-gh bot added the pr-not-for-changelog This PR should not be mentioned in the changelog label Feb 12, 2026

vitlibar mentioned this pull request Feb 12, 2026

[WIP] Implement operators with aggregation on labels for our PromQL support #89356

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vitlibar requested a review from Copilot February 12, 2026 12:44

Copilot AI reviewed Feb 12, 2026

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vitlibar marked this pull request as draft February 12, 2026 12:48

vitlibar force-pushed the promql-implement-dropping-metric-name branch from 72704fa to f98a392 Compare February 12, 2026 14:29

vitlibar marked this pull request as ready for review February 12, 2026 14:31

vitlibar force-pushed the promql-implement-dropping-metric-name branch 2 times, most recently from 8b3a77a to fe1930a Compare February 12, 2026 15:25

vitlibar added the comp-promql PromQL / time-series subsystem: TimeSeries storage engine, PromQL parser, PromQL-to-SQL converter... label Feb 12, 2026

vitlibar force-pushed the promql-implement-dropping-metric-name branch 3 times, most recently from 2bbe0f4 to f49bb62 Compare February 12, 2026 16:05

vitlibar marked this pull request as draft February 12, 2026 16:16

vitlibar changed the title ~~PromQL: implement dropping metric name~~ [WIP] PromQL: implement dropping metric name Feb 12, 2026

vitlibar force-pushed the promql-implement-dropping-metric-name branch from f49bb62 to 73a8cf4 Compare February 13, 2026 10:41

Add function timeSeriesThrowDuplicateSeriesIf()

0a7be84

vitlibar force-pushed the promql-implement-dropping-metric-name branch from 73a8cf4 to e663b1e Compare February 13, 2026 10:55

vitlibar changed the title ~~[WIP] PromQL: implement dropping metric name~~ PromQL: implement dropping metric name Feb 13, 2026

vitlibar requested a review from Copilot February 13, 2026 10:55

Copilot started reviewing on behalf of vitlibar February 13, 2026 10:56 View session

vitlibar force-pushed the promql-implement-dropping-metric-name branch from e663b1e to da4e8f1 Compare February 13, 2026 11:00

Copilot AI reviewed Feb 13, 2026

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src/Storages/TimeSeries/PrometheusQueryToSQL/dropMetricName.cpp Outdated Show resolved Hide resolved

src/Storages/TimeSeries/PrometheusQueryToSQL/dropMetricName.cpp Outdated Show resolved Hide resolved

Implement dropping the metric name after calling over-range functions.

652d772

vitlibar force-pushed the promql-implement-dropping-metric-name branch from da4e8f1 to 42ca95d Compare February 13, 2026 16:48

vitlibar added 2 commits February 13, 2026 21:27

Fix tests

7f6e2bf

Add test

5d71994

vitlibar force-pushed the promql-implement-dropping-metric-name branch from 42ca95d to 21af638 Compare February 13, 2026 20:27

vitlibar marked this pull request as ready for review February 13, 2026 20:36

Enable promql experimental functions for Prometheus in tests.

86c4ca8

vitlibar force-pushed the promql-implement-dropping-metric-name branch from 21af638 to 86c4ca8 Compare February 16, 2026 10:16

vitlibar assigned nikitamikhaylov Feb 16, 2026

vitlibar commented Feb 16, 2026

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nikitamikhaylov approved these changes Feb 20, 2026

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nikitamikhaylov added this pull request to the merge queue Feb 20, 2026

Merged via the queue into ClickHouse:master with commit 4918ce8 Feb 20, 2026
138 of 141 checks passed

robot-ch-test-poll4 added the pr-synced-to-cloud The PR is synced to the cloud repo label Feb 20, 2026

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PromQL: implement dropping metric name#96741

PromQL: implement dropping metric name#96741
nikitamikhaylov merged 5 commits intoClickHouse:masterfrom
vitlibar:promql-implement-dropping-metric-name

vitlibar commented Feb 12, 2026 •

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edited by nikitamikhaylov

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vitlibar commented Feb 16, 2026

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vitlibar commented Feb 12, 2026 •

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