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sqlplan-compare skillA

sqlplan-compare is agent-read markdown (skill) from vanterx/mssql-performance-skills: Diff two SQL Server execution plans (baseline vs regression) to identify what changed — join strategies, memory grants, operator topology, new warnings, and missing indexes. Applies 20 checks (C1–C20). Use when a query regressed after a deployment, statistics update, schema change, or SQL Server version upgrade..

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What the file says

# SQL Server Execution Plan Comparison Skill

## Purpose

Identify what changed between two execution plans for the same query — one known-good (baseline) and one regressed (new). Produce a side-by-side diff that explains why the query is slower and what to fix. Applies 20 regression checks (C1–C20).

## Input

Accept any of:
- Two `.sqlplan` file paths: `baseline.sqlplan` and `new.sqlplan`
- Two blocks of raw `.sqlplan` XML pasted inline, labeled Baseline and New
- A description of both plans if XML is not available

## How to Run

1. Parse both plans independently
2. Extract the comparison metrics listed below for each plan
3. Produce a side-by-side diff table, then a findings section for every significant change
4. Conclude with a prioritized fix list

---

## Metrics to Compare

### Statement-Level

| Metric | Where to Find | Signal |
|--------|--------------|--------|
| StatementSubTreeCost | `StmtSimple/@StatementSubTreeCost` | > 2× increase = regression |
| DegreeOfParallelism | `QueryPlan/@DegreeOfParallelism` | DOP drop = serial plan forced |
| GrantedMemory (KB) | `MemoryGrantInfo/@GrantedMemory` | > 2× increase = cardinality inflation |
…

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How to install

Latest version
mdr add vanterx/mssql-performance-skills/sqlplan-compare@git:20260607.6ff4f7a
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Versions

versioncommittedcommitsizeaudit
git:20260607.6ff4f7a latest2026-06-07 6ff4f7a 16,652 BA view · diff
git:20260605.9ec0ebe2026-06-05 9ec0ebe 16,651 BA view · diff
git:20260603.6f65dab2026-06-03 6f65dab 16,654 BA view · diff
git:20260531.e1335232026-05-31 e133523 16,037 BA view · diff
git:20260529.c32faaf2026-05-29 c32faaf 11,543 BA view

Audit of the latest version

A  17 of 17 checks passed. Deterministic, no model, same answer every run.
  • pass: Frontmatter block present
  • pass: Frontmatter declares a name
  • pass: Frontmatter declares a description
  • pass: Size between 200 bytes and 200 KB (16652 bytes)
  • pass: No zero-width or bidi control characters
  • pass: No instruction hidden inside an HTML comment
  • pass: No link to an exfiltration or paste host
  • pass: No credential-shaped string
  • pass: No instruction to send local credentials anywhere
  • pass: No text hidden with inline styles
  • pass: No prompt-injection phrasing
  • pass: No curl or wget piped into a shell
  • pass: No recursive delete of root, home or parent
  • pass: No instruction to read or print local credentials
  • pass: No base64 blob over 200 characters
  • pass: No link to a raw IP address
  • pass: No script tag

Source

GitHub

vanterx/mssql-performance-skills · 5 stars · license MIT · pushed 2026-09-19 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_mxgnekwqhsnke4gb
GET https://markdownregistry.com/api/v1/resolve?ref=vanterx/mssql-performance-skills/sqlplan-compare
GET https://markdownregistry.com/api/v1/blob/1ddc8392b441cf031c020e5b6f3d77c00bbea79fe4467993179d6cf8fe1a6bd2

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