Sqlx Code Review

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.

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.