fix(db): resolve the events alias for one_event_per_user + breakdown

[serhiy-bzhezytskyy]

fixes #502.

What changed

Breakdown SELECT expressions are always built with the events alias (getSelectPropertyKey(breakdown.name, ..., 'e') at chart.service.ts:766 and :1108, rendering e.properties['linked']). The one_event_per_user segment replaces FROM with a subquery aliased subQuery (chart.service.ts:820 and :1170, before this change), so e is out of scope in the outer query — any chart combining that segment with a property breakdown failed with Unknown expression or function identifier e.properties. #502 reported this on getAggregateChartSql; the same defect is in getChartSql too, unreported so far because no existing test paired one_event_per_user with a breakdown.

The fix aliases the subquery e instead of subQuery in both builders. It already does SELECT * FROM events e, so every existing e.-qualified reference in the outer query resolves without touching the breakdown/select code at all.

Evidence

• chart.service.ts:766, :1108 — the breakdown SELECT, hardcoded to alias e.
• chart.service.ts:820, :1170 (before this change) — the subquery aliased subQuery, the alias e falls out of scope here.
• chart.service.ts:822-826 — getChartSql already clears sb.where after building the subquery's filter, with a comment naming the same "alias out of scope" reasoning this fix now also resolves. getAggregateChartSql does not clear it, so before this change it was broken on both the outer SELECT and the outer WHERE; after, the outer WHERE is redundant (re-applies the same filter the subquery already applied) but valid, since e now resolves.

Tests

Added to chart-sql.test.ts, one case per builder: one_event_per_user segment + a properties.* breakdown, run through EXPLAIN against a local ClickHouse. Both fail with the reported UNKNOWN_IDENTIFIER on the current code and pass with the change. The pre-existing no-breakdown case (one_event_per_user segment still parses) already passed before this change, matching why the bug went unreported in the series builder.

Deliberately left out

• getAggregateChartSql's redundant outer WHERE after this change is not removed. Clearing it would match getChartSql's shape, but it's a second, unrelated cleanup on a function this fix otherwise leaves alone.
• getSelectPropertyKey's eventsAlias parameter and the breakdown-building loop are untouched; the alternative fix in one_event_per_user segment + breakdown fails: Unknown expression or function identifier e.properties #502 (pass no alias there) was not taken, since it would leave the aggregate builder's outer WHERE broken without also touching sb.where.
• No reformatting.

Checks

• vitest run on chart-sql.test.ts — 38 passed (was 36 before the 2 new cases). Full db package — 308 passed.
• tsc --noEmit in packages/db — passes.
• biome check on the touched files — 26 pre-existing noMisplacedAssertion findings on chart-sql.test.ts's itCH wrapper, unchanged before/after; none in chart.service.ts.

Assisted by Claude Code.

Summary by CodeRabbit

• Bug Fixes

  • Fixed aggregate chart queries for one-event-per-user segments with profile or group filters.
  • Prevented invalid filter references from causing SQL errors when generating these charts.

• Tests

  • Added coverage confirming filtered aggregate chart queries produce valid SQL execution plans.

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• packages/db/src/services/chart-sql.test.ts
• packages/db/src/services/chart.service.ts

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📝 Walkthrough

Walkthrough

The aggregate one-event-per-user SQL path now clears filters after removing subquery-scoped joins. A test covers a group.plan filter and verifies that the generated SQL parses.

Changes

Aggregate chart filter correction

Layer / File(s)	Summary
Outer filter reset and SQL validation packages/db/src/services/chart.service.ts, packages/db/src/services/chart-sql.test.ts	The aggregate chart builder clears sb.where after clearing joins in the one_event_per_user branch. The test validates SQL generation with a group.plan filter using EXPLAIN.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: niajkitir

Merge Risk: ⚪ Minimal · up to 3f3af

The aggregate query retains its event filters inside the inner distinct query, so the change is mergeable.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the primary fix: resolving the events alias for one_event_per_user charts with breakdowns. It is concise and specific to the changeset.
Linked Issues check	✅ Passed	The PR satisfies issue #502. Both one_event_per_user SQL builders alias the filtered subquery as e, so e.properties and e.name remain valid in the outer query. Regression tests cover the aggre…
Out of Scope Changes check	✅ Passed	The changes remain within issue #502. The alias updates fix the reported SQL scope error. The sb.where reset and its group-filter regression test address the same one_event_per_user subquery scope…

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Actionable comments posted: 1

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Inline comments:
In `@packages/db/src/services/chart.service.ts`:
- Line 1170: In getAggregateChartSql, update the one_event_per_user branch to
clear sb.where immediately after replacing sb.from with the wrapped filtered
subquery, before calling getSql(), while preserving the existing join reset. Add
a regression case covering a profile or group filter to verify the generated SQL
does not reference out-of-scope aliases.

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📒 Files selected for processing (2)

• packages/db/src/services/chart-sql.test.ts
• packages/db/src/services/chart.service.ts

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