sqlx-code-review

name	sqlx-code-review
description	Reviews sqlx database code for compile-time query checking, connection pool management, migration patterns, and PostgreSQL-specific usage. Use when reviewing Rust code that uses sqlx, database queries, connection pools, or migrations. Covers offline mode, type mapping, and transaction patterns.

sqlx Code Review

Review Workflow

1. Check Cargo.toml — Note sqlx features (runtime-tokio, tls-rustls/tls-native-tls, postgres/mysql/sqlite, uuid, chrono, json, migrate) and Rust edition (2024 changes RPIT lifetime capture and removes need for async-trait)
2. Check query patterns — Compile-time checked (query!, query_as!) vs runtime (query, query_as)
3. Check pool configuration — Connection limits, timeouts, idle settings
4. Check migrations — File naming, reversibility, data migration safety
5. Check type mappings — Rust types align with SQL column types

Gates (evidence before severity)

Complete in order; do not assign Critical / Major until the gate for that claim is passed.

1. Scope — Identify the crate under review (Cargo.toml path) and the .rs files (or directory) you opened. Pass: At least one concrete path you inspected is named.
2. sqlx / compile claims — Before asserting issues about query! / query_as!, offline mode, sqlx.toml, DATABASE_URL, or Cargo features: open the relevant Cargo.toml and, if applicable, sqlx.toml or documented env. Pass: The finding cites a line or you state that those files were absent / out of scope.
3. Finding anchors — Each reported issue includes [FILE:LINE] per Output Format. Pass: No Critical or Major without a line reference.
4. Protocol — Load and complete the review-verification-protocol skill after gates 1–3 and before final severity labels. Pass: Protocol steps satisfied for each retained finding.

Output Format

Report findings as:

[FILE:LINE] ISSUE_TITLE
Severity: Critical | Major | Minor | Informational
Description of the issue and why it matters.

Quick Reference

Issue Type	Reference
Query macros, bind parameters, result mapping	references/queries.md
Migrations, pool config, transaction patterns	references/migrations.md

Review Checklist

Query Patterns

• Compile-time checked queries (query!, query_as!) used where possible
• sqlx.toml or DATABASE_URL configured for offline compile-time checking
• No string interpolation in queries (SQL injection risk) — use bind parameters ($1, $2)
• query_as! maps to named structs, not anonymous records, for public APIs
• .fetch_one(), .fetch_optional(), .fetch_all() chosen appropriately
• .fetch() (streaming) used for large result sets

Connection Pool

• PgPool shared via Arc or framework state (not created per-request)
• Pool size configured for the deployment (not left at defaults in production)
• Connection acquisition timeout set
• Idle connection cleanup configured
• Edition 2024: Pool initialization uses std::sync::LazyLock (not once_cell::sync::Lazy or lazy_static!) for static pool singletons

Transactions

• pool.begin() used for multi-statement operations
• Transaction committed explicitly (not relying on implicit rollback on drop)
• Errors within transactions trigger rollback before propagation
• Nested transactions use savepoints (tx.begin()) if needed

Type Mapping

• sqlx::Type derives match database column types
• Enum representations consistent between Rust, serde, and SQL
• Uuid, DateTime<Utc>, Decimal types used (not strings for structured data)
• Option<T> used for nullable columns
• serde_json::Value used for JSONB columns
• No enum variants or struct fields named gen — reserved keyword in edition 2024 (use r#gen with #[sqlx(rename = "gen")] or choose a different name)

Edition 2024 Compatibility

• Functions returning -> impl Stream or -> impl Future account for RPIT lifetime capture changes (all in-scope lifetimes captured by default; use + use<'a> for precise control)
• Custom FromRow or Type trait impls use native async fn in traits where applicable (no #[async_trait] needed, stable since Rust 1.75)
• Prefer #[expect(unused)] over #[allow(unused)] for compile-time query fields only used in some code paths (self-cleaning lint suppression, stable since 1.81)
• Static pool initialization uses std::sync::LazyLock (not once_cell or lazy_static!)

Migrations

• Migration files follow naming convention (YYYYMMDDHHMMSS_description.sql)
• Destructive migrations (DROP, ALTER DROP COLUMN) are reversible or have data backup plan
• No data-dependent schema changes in same migration as data changes
• sqlx::migrate!() called at application startup

Severity Calibration

Critical

• String interpolation in SQL queries (SQL injection)
• Missing transaction for multi-statement writes (partial writes on error)
• Connection pool created per-request (connection exhaustion)
• Missing bind parameter escaping

Major

• Runtime queries (query()) where compile-time (query!()) could verify correctness
• Missing transaction rollback on error paths
• Enum type mismatch between Rust and database
• Unbounded .fetch_all() on potentially large tables
• Field or variant named gen without r#gen escape (edition 2024 compile failure)

Minor

• Pool defaults used in production without tuning
• Missing .fetch_optional() (using .fetch_one() then handling error for "not found")
• Overly broad SELECT * when only specific columns needed
• Missing indexes for queried columns (flag only if query pattern is clearly slow)
• Edition 2024: once_cell::sync::Lazy or lazy_static! used where std::sync::LazyLock works
• Using #[allow(unused)] instead of #[expect(unused)] for query fields (prefer self-cleaning lint suppression)

Informational

• Suggestions to use query_as! for type-safe result mapping
• Suggestions to add database-level constraints alongside Rust validation
• Migration organization improvements

Valid Patterns (Do NOT Flag)

• Runtime query() for dynamic queries — Compile-time checking doesn't work with dynamic SQL
• sqlx::FromRow derive — Valid alternative to query_as! for reusable row types
• TEXT columns for enum storage — Valid with sqlx::Type derive, simpler than custom SQL types
• .execute() ignoring row count — Acceptable for idempotent operations (upserts, deletes)
• Shared DB with other languages — e.g., Elixir owns migrations, Rust reads. This is a valid architecture.
• r#gen with #[sqlx(rename = "gen")] — Correct edition 2024 workaround for gen columns in database types
• + use<'a> on query helper return types — Precise RPIT lifetime capture (edition 2024)
• std::sync::LazyLock for static pool initialization — Replaces once_cell/lazy_static (stable since Rust 1.80)
• Native async fn in custom FromRow/Type trait impls — async-trait crate no longer needed (stable since Rust 1.75)

Before Submitting Findings

Complete Gates (evidence before severity), then load and follow the review-verification-protocol skill before reporting any issue.