Show related operator costs alongside missing index suggestions

[erikdarlingdata]

Summary

When an actual plan has missing index suggestions, correlate them with the scan operators that touch the same table and show their CPU, duration, and read costs. This gives DBAs concrete numbers alongside the optimizer's impact percentage.

Example

Currently:

Missing indexes:
  StackOverflow2013.dbo.Comments (impact: 79%)
    CREATE NONCLUSTERED INDEX [Comments_Score]
    ON [dbo].[Comments] ([Score])
    INCLUDE ([UserId]);

Proposed:

Missing indexes:
  StackOverflow2013.dbo.Comments (impact: 79%)
  Related: Clustered Index Scan (Node 8) — 5,031ms CPU, 4,372ms elapsed, 303,887 reads
    CREATE NONCLUSTERED INDEX [Comments_Score]
    ON [dbo].[Comments] ([Score])
    INCLUDE ([UserId]);

Implementation

1. PlanAnalyzer: When building MissingIndexResult, find operators where Object contains the missing index table name AND the operator is a scan (Clustered Index Scan, Index Scan, Table Scan). Store their stats.
2. MissingIndexResult: Add fields for related operator summaries (name, node ID, CPU, elapsed, reads). Could be a list if multiple scans hit the same table.
3. TextFormatter: Output the "Related:" line between the impact line and CREATE statement.
4. AdviceContentBuilder: Style the related operator line.

Notes

• Table name matching needs substring logic: Object is dbo.Comments.PK_Comments_Id, missing index table is dbo.Comments
• Only available in actual plans (estimated plans have no runtime stats) — skip gracefully
• All three PlanAnalyzer copies (PerformanceStudio, Dashboard, Lite) need the update
• We can show operator costs but cannot precisely predict seek savings (depends on selectivity)

🤖 Generated with Claude Code