Adding JDBC Data Reader

extras/jdbc_read/.gitignore

@@ -0,0 +1,4 @@
+target/classes
+target/maven-status
+target/maven-archiver
+

extras/jdbc_read/README.md

@@ -0,0 +1,41 @@
+# JDBC Data Reader for Snowpark
+
+See[ medium article for more details.](https://medium.com/@orellabac/ingest-external-data-into-snowflake-with-snowpark-and-jdbc-eb487b61078c)
+
+**Building**
+
+```
+mvn clean package
+```
+
+The target file will be at:  `target/snowpark-jdbc-reader-0.0.1.jar`
+
+For convience there is a prebuilt-jar you can use. 
+
+**Deployment**
+
+upload the jar to snowflake, you can use the [SnowSight UI to do that easily ](https://docs.snowflake.com/en/user-guide/data-load-local-file-system-stage-ui)
+
+and create an UDF like this:
+
+```
+CREATE OR REPLACE SECRET external_database_cred
+    TYPE = password
+    USERNAME = 'serveradmin'
+    PASSWORD = 'xxxxxxxxx';
+
+CREATE OR REPLACE EXTERNAL ACCESS INTEGRATION external_database_network_rule_ext_int
+  ALLOWED_NETWORK_RULES = (external_database_network_rule)
+  ALLOWED_AUTHENTICATION_SECRETS = (external_database_cred)
+  ENABLED = true;
+
+
+CREATE OR REPLACE FUNCTION READ_JDBC(OPTION OBJECT, query STRING)
+  RETURNS TABLE(data OBJECT)
+  LANGUAGE JAVA
+RUNTIME_VERSION='11'
+  IMPORTS = ('@mystage/snowpark-jdbc-reader-0.0.1.jar' ) -- Add the jar for any jdbc driver you need in this section
+  EXTERNAL_ACCESS_INTEGRATIONS = (external_database_network_rule_ext_int)
+  SECRETS = ('cred' = external_database_cred )
+  HANDLER = 'JdbcDataReader';
+```

extras/jdbc_read/pom.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.snowflake</groupId>
+  <artifactId>snowpark-jdbc-reader</artifactId>
+  <version>0.0.1</version>
+
+  <name>Simple JDBC reader</name>
+
+  <url>https://medium.com/@orellabac/ingest-external-data-into-snowflake-with-snowpark-and-jdbc-eb487b61078c</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>com.snowflake</groupId>
+      <artifactId>snowpark</artifactId>
+      <version>1.9.0</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.11</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>
+  </build>
+</project>

extras/jdbc_read/src/main/java/JdbcDataReader.java

@@ -0,0 +1,86 @@
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.sql.*;
+import java.util.*;
+import java.util.stream.Stream;
+import com.snowflake.snowpark_java.types.SnowflakeSecrets;
+
+public class JdbcDataReader {
+
+    public static class OutputRow {
+        public Map<String, String> data;
+
+        public OutputRow(Map<String, String> data) {
+            this.data = data;
+        }
+    }
+
+    public static Class getOutputClass() {
+      return OutputRow.class;
+    }
+
+    public Stream<OutputRow> process(Map<String, String> jdbcConfig, String query) {
+        String jdbcUrl = jdbcConfig.get("url");
+        Properties properties = new Properties();
+
+        if ("true".equals(jdbcConfig.get("use_secrets")))
+        {
+            SnowflakeSecrets sfSecrets = SnowflakeSecrets.newInstance();
+            jdbcConfig.remove("use_secrets");
+            var secret = sfSecrets.getUsernamePassword("cred");
+            properties.setProperty("username", secret.getUsername());
+            properties.setProperty("password", secret.getPassword());
+        }
+
+        try {
+            properties.putAll(jdbcConfig);
+            // Load the JDBC driver 
+            Class.forName(jdbcConfig.get("driver"));
+            // Create a connection to the database
+            Connection connection = DriverManager.getConnection(jdbcUrl, properties);
+            // Create a statement for executing SQL queries
+            Statement statement = connection.createStatement();
+            // Execute the query
+            ResultSet resultSet = statement.executeQuery(query);
+            // Get metadata about the result set
+            ResultSetMetaData metaData = resultSet.getMetaData();
+            // Create a list of column names
+            List<String> columnNames = new ArrayList<>();
+            int columnCount = metaData.getColumnCount();
+            for (int i = 1; i <= columnCount; i++) {
+                columnNames.add(metaData.getColumnName(i));
+            }
+            // Convert the ResultSet to a Stream of OutputRow objects
+            Stream<OutputRow> resultStream = Stream.generate(() -> {
+                try {
+                    if (resultSet.next()) {
+                        Map<String, String> rowMap = new HashMap<>();
+                        for (String columnName : columnNames) {
+                            String columnValue = resultSet.getString(columnName);
+                            rowMap.put(columnName, columnValue);
+                        }
+                        return new OutputRow(rowMap);
+                    } else {
+                        // Close resources
+                        resultSet.close();
+                        statement.close();
+                        connection.close();                        
+                        return null;
+                    }
+                } catch (SQLException e) {
+                    e.printStackTrace();
+                    return null;
+                }
+            }).takeWhile(Objects::nonNull);
+            return resultStream;
+        } catch (Exception e) {
+            StringWriter sw = new StringWriter();
+            PrintWriter pw = new PrintWriter(sw);
+            e.printStackTrace(pw);
+            String stackTrace = sw.toString();
+            Map<String, String> rowMap = new HashMap<>();
+            rowMap.put("ERROR",e.getMessage() + "\n" + stackTrace);
+            return Stream.of(new OutputRow(rowMap));
+        }
+    }
+}