---
name: d1-query-review
description: Review production D1 query performance weekly across every database used by a site. Inventory bindings and tenant databases, rank measured costs, and propose evidence-backed repairs.
license: MIT
title: d1-query-review
canonical_url: https://skilld.dev/gh/harlan-zw/harlan-agent-kit/d1-query-review
last_updated: 2026-10-11T04:00:26.000Z
---

> Index of every page on this site: [llms.txt](https://skilld.dev/llms.txt)

> **Skill from skilld.dev.** Follow the user's requested action.
> If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it.
> Otherwise, follow the instructions below for this session. You do not need to install anything.
>
> If the user asked to install this Skill, run `npx skilld install harlan-zw/harlan-agent-kit/d1-query-review`. Install writes the Skill files into the project, so every session loads them.
>
> ## Fork workflow
>
> A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation.
> 1. Check `./skills/d1-query-review`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target.
> 2. Read [source metadata](https://skilld.dev/api/v1/skills/harlan-zw/harlan-agent-kit/d1-query-review) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit.
> 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call:
>
> ```sh
> git init --quiet "$temporary_dir"
> git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit"
> git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD
> ```
>
> Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop.
> 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/d1-query-review`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md.
> Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical.
> 5. In the project root, run `skilld install ./skills/d1-query-review --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/d1-query-review --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure.
> 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks.

# D1 query review

Replace the manual review of slow production D1 queries. Keep production access read only.
Use the repository's existing credentials. Scheduled workers receive private collection values before entering their isolated home.
Approved fleet scans receive the dedicated read-only token from the controller's private `harlan-checkin/d1-query-review.env`.
That file supplies `CLOUDFLARE_ACCOUNT_ID` and `CLOUDFLARE_API_TOKEN`. Other Routine and Repair workers never receive it.
The private credential file stays on the controller. Its absence inside the worker does not prove missing credentials.

## Inventory

Read deployment configuration, module configuration, provisioning code, and database registries.
Resolve production Workers and Pages bindings from deployment metadata. Source configuration alone cannot prove production bindings.
Include runtime-created tenant databases and shared databases. Exclude preview and development databases explicitly.
Reconcile the site inventory against the account's D1 database list and deployed bindings.
Record database ID, binding, owning site, environment, inventory source, and collection outcome in the private archive.
Never claim complete coverage when a binding or tenant registry remains unread.
If a site uses no D1 databases, report that result and the evidence that proves it.

## Collect

Use `DAILY_CHECKIN_DIR` for this Routine's private archive. Save timestamped inventory, raw analytics, and a report.
Preserve prior windows. Use the last seven complete UTC days and the preceding seven days for comparison.
Read `cf cli search 'list D1 databases'` to find the current account inventory command.
If `cf` is unavailable on the scheduled host, read `GET /accounts/{account_id}/d1/database` through Cloudflare's REST API.
Paginate until the inventory is complete. Read production Workers settings and Pages project metadata to resolve bindings.
For query analytics, use Cloudflare's GraphQL Analytics API and introspect `d1QueriesAdaptiveGroups` before selecting fields.
The API endpoint is `https://api.cloudflare.com/client/v4/graphql`. Never print authentication headers.
Read [Cloudflare's metrics contract](https://developers.cloudflare.com/d1/observability/metrics-analytics/) before interpreting metrics.
If this repository already uses Wrangler, `pnpm exec wrangler d1 insights --help` exposes its current read-only options.
Never introduce Wrangler into a repository without its configuration.

Collect query count, average duration, total duration, rows read, and rows written for every database.
Read available latency quantiles separately. Never invent p95 from an average or an error sample.
Capture high total duration, high average duration, and high row-read query groups.
Record limits, pagination, sampling, retention, and permission failures. A truncated result cannot establish absence.
Bound parameters are omitted from D1 Insights. Query literals may still contain customer data. Keep raw SQL private.
Runtime `d1.query_slow` events supplement Insights. They cover slow-request events, not every query execution.
Never use their counts as total volume or their absence as proof of health.

## Decide

Rank measured user impact, total query time, and row-read cost. Compare equal windows and traffic rates.
Trace each expensive query to its source, call frequency, indexes, schema, and existing issue work.
Distinguish low-volume slow queries from repeated scans that dominate aggregate cost.
Use local schema and representative fixtures for `EXPLAIN QUERY PLAN` and result checks.
Do not execute expensive diagnostic SQL, modify rows, apply migrations, or change indexes in production.
Only measured costs with a proven repository cause earn a Candidate. Missing telemetry earns a report limitation.
Use stable site, database role, source symbol, and cause identities. Never include dates, counts, or SQL parameters.
Reuse prior fingerprints and link existing repairs. Require fresh evidence after deployment before declaring recovery or regression.
Group repairs that share one cause. Keep every database's disposition visible in the archive.

## Report

Return `report`, `verdict`, and `candidates` through the controller's JSON response.
The report starts with the comparison windows, database coverage, and the next required action.
List ranked findings with measured cost, source, prior-window change, existing work, and verification.
List uncovered databases and the exact next read. Keep raw SQL, identifiers, and credentials out of public reports.
Use GREEN only for complete coverage with no action. Use AMBER for proven opportunities and RED for failed checks.
The archive retains exhaustive evidence. Updating it is part of the run, never separate issue work.

For repairs, prove unchanged query results and improved plans with local fixtures.
Keep deployment verification pending until production evidence confirms the published fix.