feat: Add Oracle table provider with rust-oracle driver

Implement Oracle support using rust-oracle (ODPI-C) and bb8 connection pooling.
Includes comprehensive type mappings (NUMBER, DATE, TIMESTAMP, CLOB, BLOB, RAW),
schema inference, and 12 integration tests.
Tested against Oracle Database 23c Free.

Note: This is my first contribution to the project. Feedback welcome! :)

Author: banickn

Cargo.lock

@@ -22,6 +22,7 @@ let ctx = SessionContext::with_state(state);
 
 - PostgreSQL
 - MySQL
+- Oracle
 - SQLite
 - ClickHouse
 - DuckDB
@@ -165,6 +166,57 @@ EOF
 cargo run -p datafusion-table-providers --example mysql --features mysql
 ```
 
+### Oracle
+
+In order to run the Oracle example, you need to have an Oracle database server running. You can use the following command to start an Oracle Free server in a Docker container the example can use:
+
+```bash
+docker run --name oracle-free \
+    -e ORACLE_PASSWORD=OraclePassword123 \
+    -p 1521:1521 \
+    -d gvenzl/oracle-free:latest
+
+# Wait for the Oracle server to start and healthcheck to pass
+echo "Waiting for Oracle to start (this may take 1-2 minutes)..."
+until docker exec oracle-free /usr/local/bin/checkHealth.sh >/dev/null 2>&1; do
+    sleep 5
+done
+echo "Oracle is ready!"
+
+# Create a table in the Oracle server and insert some data
+docker exec -i oracle-free sqlplus system/OraclePassword123@FREEPDB1 <<EOF
+CREATE TABLE companies (
+   id NUMBER PRIMARY KEY,
+   name VARCHAR2(100)
+);
+
+INSERT INTO companies (id, name) VALUES (1, 'Acme Corporation');
+INSERT INTO companies (id, name) VALUES (2, 'Widget Inc.');
+COMMIT;
+EXIT;
+EOF
+```
+
+**Prerequisites:** The `rust-oracle` crate requires Oracle Instant Client libraries (ODPI-C). Install them:
+
+- **Linux (Debian/Ubuntu):**
+  ```bash
+  apt-get install libaio1 wget unzip
+  wget https://download.oracle.com/otn_software/linux/instantclient/instantclient-basiclite-linuxx64.zip
+  unzip instantclient-basiclite-linuxx64.zip -d /opt/oracle
+  export LD_LIBRARY_PATH=/opt/oracle/instantclient_XX_X:$LD_LIBRARY_PATH
+  ```
+
+- **macOS:**
+  ```bash
+  brew install instantclient-basic
+  ```
+
+```bash
+# Run from repo folder
+cargo run -p datafusion-table-providers --example oracle --features oracle
+```
+
 ### Flight SQL
 
 ```bash

README.md

@@ -103,6 +103,8 @@ rust_decimal = { version = "1.38.0", features = ["db-postgres"] }
 adbc_driver_manager = { workspace = true, optional = true }
 adbc_core = { workspace = true, optional = true }
 r2d2_adbc = { version = "0.2.0", optional = true }
+oracle = { version = "0.6", optional = true }
+bb8-oracle = { version = "0.3", optional = true }
 
 [dev-dependencies]
 anyhow = "1.0"
@@ -167,6 +169,14 @@ adbc = [
   "dep:r2d2",
 ]
 adbc-federation = ["adbc", "federation"]
+oracle = [
+  "dep:oracle", 
+  "dep:bb8",
+  "dep:bb8-oracle", 
+  "dep:async-stream", 
+  "dep:arrow-schema",
+]
+oracle-federation = ["oracle", "federation"]
 
 # docs.rs-specific configuration
 [package.metadata.docs.rs]

core/Cargo.toml

@@ -17,6 +17,8 @@ pub mod flight;
 pub mod mysql;
 #[cfg(feature = "odbc")]
 pub mod odbc;
+#[cfg(feature = "oracle")]
+pub mod oracle;
 #[cfg(feature = "postgres")]
 pub mod postgres;
 #[cfg(feature = "sqlite")]