Struct DatabasePool 

pub struct DatabasePool { /* private fields */ }

Multi-database connection pool with lazy shard opening.

Wraps a default Database (the main database) plus a sharded cache of lazily-opened shard databases. All shards share the same PRAGMAs and migrations from the parent Config.

Cloning is cheap (reference count increment via Arc).

Examples

use modo::db::{self, ConnExt, ConnQueryExt, DatabasePool};

let pool = DatabasePool::new(&config).await?;

// Default database:
let user: User = pool.conn(None).await?
    .conn()
    .query_one("SELECT id, name FROM users WHERE id = ?1", libsql::params!["u1"])
    .await?;

// Tenant shard (lazy open + cache):
let user: User = pool.conn(tenant.db_shard.as_deref()).await?
    .conn()
    .query_one("SELECT id, name FROM users WHERE id = ?1", libsql::params!["u1"])
    .await?;

Implementations

impl DatabasePool

pub async fn new(config: &Config) -> Result<Self>

Create a new pool from the given config.

Opens the default database immediately. Shard databases are opened lazily on first conn call.

Errors

Returns an error if config.pool is None or the default database fails to open.

pub async fn conn(&self, shard: Option<&str>) -> Result<Database>

Get a database connection by shard name.

• None — returns the default database (instant, no lock).
• Some("name") — returns the cached shard database, opening it on first access at {base_path}/{name}.db.

Concurrent first-access to the same shard may open duplicate connections; the last writer wins and the extra connection is dropped. This is benign because connect is idempotent (PRAGMAs are re-applied, migrations use checksum tracking).

Errors

Returns an error if the shard name is invalid (empty, starts with ., or contains path separators or a null byte) or if the shard database fails to open.

Trait Implementations

impl Clone for DatabasePool

fn clone(&self) -> DatabasePool

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.