feat: add MySQL metadata provider support

Cargo.toml

@@ -51,8 +51,8 @@ skip-tests-with-docker = []
 # Metadata provider backends
 metadata-duckdb = ["dep:duckdb"]
 metadata-postgres = ["dep:sqlx", "sqlx/postgres", "sqlx/chrono"]
+metadata-mysql = ["dep:sqlx", "sqlx/mysql", "sqlx/chrono"]
 # Future: metadata-sqlite = ["sqlx", "sqlx/sqlite", "sqlx/chrono"]
-# Future: metadata-mysql = ["sqlx", "sqlx/mysql", "sqlx/chrono"]
 
 # Encryption support for Parquet files
 encryption = ["parquet/encryption", "datafusion/parquet_encryption", "dep:base64", "dep:hex"]

examples/basic_query.rs

@@ -1,7 +1,7 @@
 //! Basic DuckLake query example with snapshot isolation
 //!
 //! This example demonstrates how to:
-//! 1. Create a DuckLake catalog from DuckDB or PostgreSQL
+//! 1. Create a DuckLake catalog from DuckDB, PostgreSQL, or MySQL
 //! 2. Bind the catalog to a specific snapshot for query consistency
 //! 3. Register it with DataFusion
 //! 4. Execute a simple SELECT query
@@ -29,11 +29,20 @@
 //!   "postgresql://user:password@localhost:5432/postgres" \
 //!   "SELECT * FROM main.users"
 //! ```
+//!
+//! With MySQL catalog (requires --features metadata-mysql):
+//! ```bash
+//! cargo run --example basic_query --features metadata-mysql \
+//!   "mysql://user:password@localhost:3306/database" \
+//!   "SELECT * FROM main.users"
+//! ```
 
 use datafusion::execution::runtime_env::RuntimeEnv;
 use datafusion::prelude::*;
 #[cfg(feature = "metadata-duckdb")]
 use datafusion_ducklake::DuckdbMetadataProvider;
+#[cfg(feature = "metadata-mysql")]
+use datafusion_ducklake::MySqlMetadataProvider;
 #[cfg(feature = "metadata-postgres")]
 use datafusion_ducklake::PostgresMetadataProvider;
 use datafusion_ducklake::{DuckLakeCatalog, MetadataProvider, register_ducklake_functions};
@@ -53,13 +62,17 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         eprintln!(
             "  PostgreSQL: cargo run --example basic_query --features metadata-postgres \"postgresql://...\" \"SQL\""
         );
+        eprintln!(
+            "  MySQL:      cargo run --example basic_query --features metadata-mysql \"mysql://...\" \"SQL\""
+        );
         exit(1);
     }
     let catalog_source = &args[1];
     let sql = &args[2];
 
     // Detect provider type based on input
     let is_postgres = catalog_source.starts_with("postgresql://");
+    let is_mysql = catalog_source.starts_with("mysql://");
 
     if is_postgres {
         #[cfg(not(feature = "metadata-postgres"))]
@@ -77,6 +90,22 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             println!("Current snapshot ID: {}", snapshot_id);
             run_query(provider, snapshot_id, sql).await?;
         }
+    } else if is_mysql {
+        #[cfg(not(feature = "metadata-mysql"))]
+        {
+            eprintln!("Error: MySQL support requires the 'metadata-mysql' feature");
+            eprintln!("Run with: cargo run --example basic_query --features metadata-mysql");
+            exit(1);
+        }
+
+        #[cfg(feature = "metadata-mysql")]
+        {
+            println!("Connecting to MySQL catalog: {}", catalog_source);
+            let provider = Arc::new(MySqlMetadataProvider::new(catalog_source).await?);
+            let snapshot_id = provider.get_current_snapshot()?;
+            println!("Current snapshot ID: {}", snapshot_id);
+            run_query(provider, snapshot_id, sql).await?;
+        }
     } else {
         #[cfg(feature = "metadata-duckdb")]
         {

src/error.rs

@@ -18,8 +18,8 @@ pub enum DuckLakeError {
     #[error("DuckDB error: {0}")]
     DuckDb(#[from] duckdb::Error),
 
-    /// sqlx database error (for PostgreSQL metadata provider)
-    #[cfg(feature = "metadata-postgres")]
+    /// sqlx database error (for PostgreSQL/MySQL metadata providers)
+    #[cfg(any(feature = "metadata-postgres", feature = "metadata-mysql"))]
     #[error("Database error: {0}")]
     Sqlx(#[from] sqlx::Error),
 

src/lib.rs

@@ -52,6 +52,8 @@ pub mod types;
 // Metadata providers (feature-gated)
 #[cfg(feature = "metadata-duckdb")]
 pub mod metadata_provider_duckdb;
+#[cfg(feature = "metadata-mysql")]
+pub mod metadata_provider_mysql;
 #[cfg(feature = "metadata-postgres")]
 pub mod metadata_provider_postgres;
 
@@ -69,5 +71,7 @@ pub use table_functions::register_ducklake_functions;
 // Re-export metadata providers (feature-gated)
 #[cfg(feature = "metadata-duckdb")]
 pub use metadata_provider_duckdb::DuckdbMetadataProvider;
+#[cfg(feature = "metadata-mysql")]
+pub use metadata_provider_mysql::MySqlMetadataProvider;
 #[cfg(feature = "metadata-postgres")]
 pub use metadata_provider_postgres::PostgresMetadataProvider;

src/metadata_provider.rs

@@ -405,7 +405,7 @@ pub trait MetadataProvider: Send + Sync + std::fmt::Debug {
     ) -> Result<Vec<DeleteFileChange>>;
 }
 
-#[cfg(feature = "metadata-postgres")]
+#[cfg(any(feature = "metadata-postgres", feature = "metadata-mysql"))]
 /// Helper function to bridge async sqlx operations to sync MetadataProvider trait
 pub(crate) fn block_on<F, T>(f: F) -> T
 where