SQLx Knowledge Patch

Covers SQLx 0.8.3–0.9.0-alpha.1 (2025-01-03 through 2025-10-14). Claude Opus 4.6 knows SQLx through 0.7.x. It is unaware of the 0.8+ features and 0.9 breaking changes below.

Index

Topic	Reference	Key features
Transactions	references/transactions.md	begin_with, per-DB option types, is_in_transaction, type aliases
Type system & macros	references/type-system.md	SqlSafeStr, Arguments lifetime removal, smart pointer Encode/Decode, PgBindIter, PgHasArrayType auto-derive, json(nullable), transparent named structs
SQLite	references/sqlite.md	Commit/rollback/preupdate hooks, feature flags (sqlite-deserialize, sqlite-load-extension, sqlite-unlock-notify), sqlite-unbundled, no_tx migrations
Postgres & MySQL	references/postgres-and-mysql.md	Geometry types, ipnet support, PgConnectOptions auto-escaping, MySQL collation inference, PgListener improvements
Configuration & runtime	references/configuration.md	sqlx.toml, MSRV 1.86, runtime feature changes, Migrator::with_migrations, RawSql type parameter

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0.8 → 0.9 Migration — Breaking Changes

Note: 0.9.0-alpha.1 is the current alpha. Many breaking changes from 0.8.x.

What changed	Before (0.8)	After (0.9)
Query string safety	query("...") accepts &str	Accepts impl SqlSafeStr — only &'static str or AssertSqlSafe
Arguments lifetime	Arguments<'q>, SqliteArguments<'q>	Arguments (no lifetime) — values are owned
Runtime features	runtime-tokio-native-tls combos	Separate runtime-tokio + native-tls; combos removed
MSRV	1.75	1.86
RawSql	No type parameter	RawSql methods require DB type parameter
RawSql::fetch_optional	Returns Result<DB::Row>	Returns Result<Option<DB::Row>>
Cow decoding	Could be Cow::Borrowed	Always Cow::Owned
SQLite extension loading	extension() safe method	unsafe; requires sqlite-load-extension feature
SqliteValue	Sync	!Sync; SqliteValueRef is !Send
MySQL text columns	Inferred as Vec<u8>	Inferred as String
PgConnectOptions::options()	Manual escaping needed	Auto-escaped — remove manual escaping
#[derive(sqlx::Type)] newtype	No auto PgHasArrayType	Auto-generates PgHasArrayType; add #[sqlx(no_pg_array)] if manual impl exists

Also note: 0.8.4 was yanked — use 0.8.5+ instead. All 0.8.4 features are available in 0.8.5.

SqlSafeStr — Query String Safety (0.9)

The most impactful breaking change. All query*() functions now take impl SqlSafeStr instead of &str. Only &'static str and AssertSqlSafe implement it.

use sqlx::AssertSqlSafe;

// Static strings work as before
sqlx::query("SELECT * FROM users WHERE id = $1")
    .bind(user_id)
    .fetch_one(&pool).await?;

// Dynamic queries must be wrapped
let table = "users";
let q = format!("SELECT * FROM {table}");
sqlx::query(AssertSqlSafe(q)).fetch_all(&pool).await?;

This also enables returning owned queries as Query<'static, DB>.

begin_with — Transaction Options (0.8.4+)

Start transactions with database-specific options:

use sqlx::postgres::{PgIsolationLevel, PgTransactionOptions};

let tx = conn
    .begin_with(
        PgTransactionOptions::new()
            .isolation_level(PgIsolationLevel::Serializable)
            .read_only(true),
    )
    .await?;

Each database has its own options type: PgTransactionOptions, MySqlTransactionOptions, SqliteTransactionOptions.

See references/transactions.md for is_in_transaction and type aliases.

Arguments Lifetime Removal (0.9)

Arguments<'q> is now just Arguments (no lifetime). SqliteArguments and AnyArguments similarly lost their lifetime parameter. Bound values are now owned.

// Before (0.8)
fn build_query<'q>(args: &mut PgArguments<'q>) { ... }

// After (0.9)
fn build_query(args: &mut PgArguments) { ... }

Smart Pointer Encode/Decode/Type (0.9)

Box<T>, Arc<T>, Rc<T>, and Cow<'_, T> now implement Encode, Decode, and Type when T does. Breaking: Cow always decodes as Cow::Owned.

PgBindIter — Bind Iterators as Arrays (0.9)

Bind iterators directly as Postgres arrays without collecting to Vec:

use sqlx::postgres::PgBindIter;

let ids = [1i32, 2, 3];
sqlx::query("SELECT * FROM users WHERE id = ANY($1)")
    .bind(PgBindIter(ids.iter()))
    .fetch_all(&pool).await?;

#[derive(sqlx::Type)] Auto-Generates PgHasArrayType (0.9)

Newtype structs deriving sqlx::Type now automatically get a PgHasArrayType impl. Add #[sqlx(no_pg_array)] to opt out:

#[derive(sqlx::Type)]
#[sqlx(no_pg_array)] // needed if you had a manual PgHasArrayType impl
struct MyId(i32);

json(nullable) and Transparent Named Structs

Handle nullable JSON columns in FromRow derives (0.8.4+):

#[derive(sqlx::FromRow)]
struct MyRow {
    #[sqlx(json(nullable))]
    metadata: Option<MyJsonType>,
}

Single-field named structs can now use #[sqlx(transparent)] (0.9):

#[derive(sqlx::Type)]
#[sqlx(transparent)]
struct UserId {
    id: i32, // single named field — now supported
}

Runtime Feature Migration (0.9)

Deprecated combination features removed. Use separate features:

# Before (0.8)
sqlx = { version = "0.8", features = ["runtime-tokio-native-tls"] }

# After (0.9)
sqlx = { version = "0.9", features = ["runtime-tokio", "native-tls"] }

New runtime options: runtime-smol and runtime-async-global-executor (replacing deprecated async-std).

sqlx.toml Configuration (0.9)

Per-crate configuration (requires sqlx-toml feature). Supports renaming DATABASE_URL, global type overrides for macros, renaming the _sqlx_migrations table, and SQLite extension loading in macros/CLI.

Guide: sqlx::_config module docs. See references/configuration.md for details.

SQLite Feature Flag Changes (0.9)

New non-default features for conditional SQLite APIs:

Feature	Enables
sqlite-deserialize	SqliteConnection::serialize() / deserialize()
sqlite-load-extension	SqliteConnectOptions::extension() (now unsafe)
sqlite-unlock-notify	Internal sqlite3_unlock_notify() usage
sqlite-preupdate-hook	conn.on_preupdate() callback (added in 0.8.4)

See references/sqlite.md for commit/rollback hooks and no_tx migrations.

New APIs Summary

API	Version	Description
conn.on_commit() / on_rollback()	0.8.3	SQLite commit/rollback hook callbacks
PgListener: Acquire + next_buffered()	0.8.3	Use PgListener as connection; batch notifications
PgPoint, PgLine	0.8.3	Postgres geometry types
Transaction type aliases	0.8.3	PgTransaction<'c>, MySqlTransaction<'c>, SqliteTransaction<'c>
sqlite-unbundled feature	0.8.3	Dynamically link system libsqlite3.so
AnyQueryResult for SQLite/MySQL	0.8.3	Previously Postgres-only
begin_with + per-DB options	0.8.4	Custom transaction isolation, read-only, etc.
Connection::is_in_transaction	0.8.4	Check if inside a transaction
conn.on_preupdate()	0.8.4	SQLite preupdate hook (requires feature)
#[sqlx(json(nullable))]	0.8.4	Handle nullable JSON columns in FromRow
PgLineSegment, PgBox, PgPath, PgPolygon, PgCircle	0.8.4	Additional Postgres geometry types
ipnet::IpNet mapping	0.8.4	Maps to Postgres INET/CIDR (requires ipnet feature)
SqlSafeStr / AssertSqlSafe	0.9	Query string safety wrapper
PgBindIter	0.9	Bind iterators as Postgres arrays
Encode/Decode for Box<T>, Arc<T>, Rc<T>, Cow<T>	0.9	Smart pointer support
#[sqlx(no_pg_array)]	0.9	Opt out of auto PgHasArrayType
#[sqlx(transparent)] on named structs	0.9	Single-field named structs (not just tuple structs)
no_tx SQLite migrations	0.9	Opt out of transaction wrapping
Migrator::with_migrations()	0.9	Build Migrator from collection programmatically
sqlx.toml configuration	0.9	Per-crate config (requires sqlx-toml feature)

Reference Files

File	Contents
transactions.md	begin_with options, isolation levels, is_in_transaction, type aliases
type-system.md	SqlSafeStr, Arguments lifetime, smart pointers, PgBindIter, PgHasArrayType, json(nullable), transparent structs
sqlite.md	Commit/rollback/preupdate hooks, feature flags, sqlite-unbundled, no_tx migrations
postgres-and-mysql.md	Geometry types, ipnet, PgConnectOptions escaping, MySQL collation, PgListener
configuration.md	sqlx.toml, MSRV/runtime changes, Migrator::with_migrations, RawSql type parameter