Crate featherdb 

FeatherDB

An embedded SQL database for AI agents. Compiles into your binary — no servers, no sockets, no C dependencies.

Built on real database internals (B-trees, WAL, MVCC) with features agents actually need: concurrent writers, encryption at rest, API key auth, and per-session isolation.

Quick Start

use featherdb::{Database, Result};

fn main() -> Result<()> {
    let db = Database::open("myapp.db")?;

    db.execute("CREATE TABLE tasks (
        id INTEGER PRIMARY KEY,
        title TEXT NOT NULL,
        status TEXT DEFAULT 'pending'
    )")?;

    db.execute("INSERT INTO tasks (id, title) VALUES (1, 'Build something cool')")?;

    let rows = db.query("SELECT * FROM tasks WHERE status = 'pending'")?;
    println!("Found {} pending tasks", rows.len());

    Ok(())
}

Transactions

use featherdb::{Database, Result};

fn main() -> Result<()> {
    let db = Database::open("myapp.db")?;

    let mut txn = db.begin()?;
    txn.execute("INSERT INTO tasks (id, title) VALUES (2, 'Ship it')")?;
    txn.execute("INSERT INTO tasks (id, title) VALUES (3, 'Celebrate')")?;
    txn.commit()?; // atomic — both rows or neither

    Ok(())
}

Encryption

use featherdb::{Config, Database, Result};

fn main() -> Result<()> {
    let config = Config::new("secrets.db").with_password("hunter2");
    let db = Database::open_with_config(config)?;
    // Every page is AES-256-GCM encrypted at rest
    Ok(())
}

Re-exports

pub use session::Session;

pub use session::SessionConfig;

pub use session::SessionHandle;

pub use session::SessionId;

pub use session::SessionManager;

pub use session::SessionManagerConfig;

pub use session::SessionMetadata;

pub use session::SessionMode;

pub use session::SessionState;

Modules

session

Session management for MCP session lifecycle.

Structs

ApiKeyInfo

Public metadata about an API key (no secrets)

BufferPoolStatsSnapshot

Immutable snapshot of buffer pool statistics

CacheStats

Statistics for the plan cache

Catalog

The schema catalog - manages all table and index definitions

Column

Column definition

ColumnDef

Column definition for schema generation

CompressionStatsSnapshot

Immutable snapshot of compression statistics

Config

Database configuration options

Database

The main database handle

DatabaseMetrics

Comprehensive database metrics snapshot

DatabaseStats

Database statistics

DeleteBuilder

Builder for DELETE queries

ExecutionContext

Execution context containing database state

Executor

Query executor

GcMetricsSnapshot

Index

Index definition

InsertBuilder

Builder for INSERT queries

Lsn

Log Sequence Number - identifies a position in the WAL

Migration

A schema migration record

Optimizer

Query optimizer that applies transformation rules

PageId

Page identifier - uniquely identifies a page in the database file

Parser

SQL parser wrapper with enhanced error messages

Permissions

Permission flags for table-level access control.

PlanCache

LRU cache for query plans

PlanCacheSnapshot

Plan cache statistics snapshot

Planner

Query planner with enhanced error messages

PreparedStatement

A prepared statement with a cached, optimized query plan

QueryBuilder

Main entry point for the query builder

QueryMetricsSnapshot

Snapshot of query metrics at a point in time

Row

A row of values

SelectBuilder

Builder for SELECT queries

Snapshot

A consistent view of the database at a point in time

StorageQuota

Storage quota information

Table

Table definition

TableGrant

A grant of permissions on a table to an API key

Transaction

A database transaction

TransactionConfig

Configuration for transaction behavior

TransactionId

Transaction identifier

TransactionManager

Manages all transactions in the database

TransactionMetricsSnapshot

Snapshot of transaction metrics at a point in time

UpdateBuilder

Builder for UPDATE queries

WalStatsSnapshot

Immutable snapshot of WAL statistics

Enums

AggregateFunction

Built-in aggregate functions

BinaryOp

Binary operations between expressions

ColumnConstraint

Column constraint

ColumnType

Column type definition

Error

Main error type for FeatherDB operations

EvictionPolicyType

Buffer pool eviction policy type

Expr

Expression tree

IndexType

Type of index

LogicalPlan

Logical plan - represents a query as a tree of relational operators

QueryOrdering

Sort ordering for ORDER BY

QueryResult

Query result - either rows or affected count Query result

TransactionMode

Transaction mode

TransactionStatus

Transaction status

UnaryOp

Unary operations on expressions

Value

A database value

Traits

FromRow

Trait for types that can be constructed from a database row

FromValue

Trait for types that can be created from a database Value

TableSchema

Trait for types that have a table schema

ToRow

Trait for types that represent a database row

ToValue

Trait for types that can be converted to a database Value

Type Aliases

Result

Result type alias using FeatherDB’s Error

SavepointId

Unique identifier for a savepoint

Derive Macros

Table

Derive macro for generating table schema and row conversion implementations