docs: update vector_extension example to run queries

Author: brianheineman

examples/vector_extension/src/main.rs

@@ -3,10 +3,11 @@
 
 use anyhow::Result;
 use indoc::indoc;
-use postgresql_embedded::{PostgreSQL, Settings, VersionReq};
-use sqlx::PgPool;
+use sqlx::{PgPool, Row};
 use tracing::info;
 
+use postgresql_embedded::{PostgreSQL, Settings, VersionReq};
+
 /// Example of how to install and configure the vector extension.
 ///
 /// See: <https://github.com/tensorchord/pgvecto.rs/?tab=readme-ov-file#quick-start>
@@ -59,6 +60,27 @@ async fn main() -> Result<()> {
     info!("Creating data");
     create_data(&pool).await?;
 
+    info!("Squared Euclidean Distance");
+    execute_query(
+        &pool,
+        "SELECT '[1, 2, 3]'::vector <-> '[3, 2, 1]'::vector AS value;",
+    )
+    .await?;
+
+    info!("Negative Dot Product");
+    execute_query(
+        &pool,
+        "SELECT '[1, 2, 3]'::vector <#> '[3, 2, 1]'::vector AS value;",
+    )
+    .await?;
+
+    info!("Cosine Distance");
+    execute_query(
+        &pool,
+        "SELECT '[1, 2, 3]'::vector <=> '[3, 2, 1]'::vector AS value;",
+    )
+    .await?;
+
     info!("Stopping database");
     postgresql.stop().await?;
     Ok(())
@@ -117,6 +139,13 @@ async fn create_data(pool: &PgPool) -> Result<()> {
     Ok(())
 }
 
+async fn execute_query(pool: &PgPool, query: &str) -> Result<()> {
+    let row = sqlx::query(query).fetch_one(pool).await?;
+    let value: f32 = row.try_get("value")?;
+    info!("{}: {}", query, value);
+    Ok(())
+}
+
 #[cfg(target_os = "linux")]
 #[cfg(test)]
 mod test {