docs: add SQLite pool configuration example

Add an example demonstrating how to configure a SQLite connection pool
using SqlitePoolOptions, including max_connections, min_connections,
acquire_timeout, idle_timeout, and max_lifetime settings.

Author: Sim-hu

Cargo.toml

@@ -25,6 +25,7 @@ members = [
     "examples/sqlite/todos",
     "examples/sqlite/extension",
     "examples/sqlite/serialize",
+    "examples/sqlite/pool-configuration",
 ]
 
 [workspace.package]

examples/sqlite/pool-configuration/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "sqlx-example-sqlite-pool-configuration"
+version = "0.1.0"
+edition = "2024"
+workspace = "../../../"
+
+[dependencies]
+sqlx = { path = "../../../", features = ["sqlite", "runtime-tokio"] }
+tokio = { version = "1.20.0", features = ["rt", "macros"] }

examples/sqlite/pool-configuration/src/main.rs

@@ -0,0 +1,64 @@
+//! Demonstrates how to configure a connection pool using `SqlitePoolOptions`.
+//!
+//! Run with:
+//!
+//! ```not_rust
+//! cargo run -p sqlx-example-sqlite-pool-configuration
+//! ```
+
+use sqlx::sqlite::SqlitePoolOptions;
+use std::time::Duration;
+
+#[tokio::main(flavor = "current_thread")]
+async fn main() -> Result<(), sqlx::Error> {
+    let pool = SqlitePoolOptions::new()
+        // Set the maximum number of connections the pool should maintain.
+        .max_connections(5)
+        // Set the minimum number of idle connections the pool should maintain.
+        .min_connections(1)
+        // Set the maximum amount of time to wait for a connection to become available.
+        .acquire_timeout(Duration::from_secs(3))
+        // Set the maximum idle duration for individual connections.
+        // Connections that sit idle longer than this are closed.
+        .idle_timeout(Duration::from_secs(60 * 10))
+        // Set the maximum lifetime of individual connections.
+        // Connections older than this are closed regardless of idle time.
+        .max_lifetime(Duration::from_secs(60 * 30))
+        // Connect to an in-memory SQLite database.
+        .connect(":memory:")
+        .await?;
+
+    // Create a table and insert some data to verify the pool works.
+    sqlx::query("CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT NOT NULL)")
+        .execute(&pool)
+        .await?;
+
+    sqlx::query("INSERT INTO users (name) VALUES (?)")
+        .bind("Alice")
+        .execute(&pool)
+        .await?;
+
+    sqlx::query("INSERT INTO users (name) VALUES (?)")
+        .bind("Bob")
+        .execute(&pool)
+        .await?;
+
+    // Query the data back.
+    let rows: Vec<(i64, String)> = sqlx::query_as("SELECT id, name FROM users ORDER BY id")
+        .fetch_all(&pool)
+        .await?;
+
+    for (id, name) in &rows {
+        println!("user: id={id}, name={name}");
+    }
+
+    // Print pool statistics.
+    println!("\nPool statistics:");
+    println!("  size:          {}", pool.size());
+    println!("  idle:          {}", pool.num_idle());
+
+    pool.close().await;
+    println!("  closed:        true");
+
+    Ok(())
+}