Handle empty result in clickhouse

[ofek1weiss]

In most warehouses, when running a query with no results, we get an empty table that contains the queried columns in return
In clickhouse, we get an empty table without any columns...

Summary by CodeRabbit

• Bug Fixes

  • Improved handling of empty query results to prevent errors during result grouping.
  • Ensures a consistent empty response when no data is returned, improving stability in edge cases.

• Chores

  • Minor internal adjustments to result processing logic for safer execution paths with no data.

[linear]

APP-60 fix group by in clickhouse

[coderabbitai]

Walkthrough

Adds a null/empty-result check to the get_result_rows_agate macro: runs the query, returns an empty object when no result is returned, otherwise groups the result by "elementary_test_results_id". Query construction is unchanged.

Changes

Cohort / File(s)	Summary of Changes
Result handling guard elementary/monitor/dbt_project/macros/get_result_rows_agate.sql	Replaced direct return of grouped query result with two-step flow: assign run_query output to res, return {} if falsy, else return res.group_by("elementary_test_results_id").

Sequence Diagram(s)

sequenceDiagram
    participant Caller
    participant Macro as get_result_rows_agate
    participant DB as elementary.run_query

    Caller->>Macro: invoke(query)
    Macro->>DB: run_query(query)
    DB-->>Macro: res

    alt res is truthy
        Note right of Macro: Group rows by "elementary_test_results_id"
        Macro-->>Caller: res.group_by("elementary_test_results_id")
    else res is null/empty
        Note right of Macro: Return empty object
        Macro-->>Caller: {}
    end

Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

I tapped my paw, awaited rows—
The query hummed, but nothing shows.
No carrots here? I won’t despair,
I’ll hand you {} with careful care.
When harvest comes, I’ll group and sort—
A tidy burrowed data report. 🥕

✨ Finishing Touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch app-60-fix-group-by-in-clickhouse

---

🪧 Tips

Chat

There are 3 ways to chat with CodeRabbit:

• Review comments: Directly reply to a review comment made by CodeRabbit. Example:
  • I pushed a fix in commit <commit_id>, please review it.
  • Open a follow-up GitHub issue for this discussion.
• Files and specific lines of code (under the "Files changed" tab): Tag @coderabbitai in a new review comment at the desired location with your query.
• PR comments: Tag @coderabbitai in a new PR comment to ask questions about the PR branch. For the best results, please provide a very specific query, as very limited context is provided in this mode. Examples:
  • @coderabbitai gather interesting stats about this repository and render them as a table. Additionally, render a pie chart showing the language distribution in the codebase.
  • @coderabbitai read the files in the src/scheduler package and generate a class diagram using mermaid and a README in the markdown format.

Support

Need help? Create a ticket on our support page for assistance with any issues or questions.

CodeRabbit Commands (Invoked using PR/Issue comments)

Type @coderabbitai help to get the list of available commands.

Other keywords and placeholders

• Add @coderabbitai ignore or @coderabbit ignore anywhere in the PR description to prevent this PR from being reviewed.
• Add @coderabbitai summary to generate the high-level summary at a specific location in the PR description.
• Add @coderabbitai anywhere in the PR title to generate the title automatically.

CodeRabbit Configuration File (.coderabbit.yaml)

• You can programmatically configure CodeRabbit by adding a .coderabbit.yaml file to the root of your repository.
• Please see the configuration documentation for more information.
• If your editor has YAML language server enabled, you can add the path at the top of this file to enable auto-completion and validation: # yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json

Status, Documentation and Community

• Visit our Status Page to check the current availability of CodeRabbit.
• Visit our Documentation for detailed information on how to use CodeRabbit.
• Join our Discord Community to get help, request features, and share feedback.
• Follow us on X/Twitter for updates and announcements.

[github-actions]

👋 @ofek1weiss
Thank you for raising your pull request.
Please make sure to add tests and document all user-facing changes.
You can do this by editing the docs files in this pull request.

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

elementary/monitor/dbt_project/macros/get_result_rows_agate.sql (1)

12-16: Also guard for empty tables and prefer explicit is none.

Some adapters return an empty agate Table (truthy) rather than None for 0 rows. In that case, group_by may still be problematic or wasteful. Using is none is clearer than not res in Jinja.

Suggested tweak:

-  {% set res = elementary.run_query(query) %}
-  {% if not res %}
-    {% do return({}) %}
-  {% endif %}
-  {% do return(res.group_by("elementary_test_results_id")) %}
+  {% set res = elementary.run_query(query) %}
+  {% if res is none or (res|length == 0) %}
+    {% do return({}) %}
+  {% else %}
+    {% do return(res.group_by("elementary_test_results_id")) %}
+  {% endif %}

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

💡 Knowledge Base configuration:

• MCP integration is disabled by default for public repositories
• Jira integration is disabled by default for public repositories
• Linear integration is disabled by default for public repositories

You can enable these sources in your CodeRabbit configuration.

📥 Commits

Reviewing files that changed from the base of the PR and between fd4bfd8 and 5f38f20.

📒 Files selected for processing (1)

• elementary/monitor/dbt_project/macros/get_result_rows_agate.sql (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: code-quality

🔇 Additional comments (2)

elementary/monitor/dbt_project/macros/get_result_rows_agate.sql (2)

12-16: Good null-guard before group_by.

Adding the guard around elementary.run_query(query) prevents calling group_by on None (likely from ClickHouse zero-row returns). Solid defensive fix.

---

12-16: Drop the return-type contract check: callers only use .get(...), which both TableSet and dict implement—returning {} is safe.

Likely an incorrect or invalid review comment.