Initial read-only Snowflake Catalog implementation by @sfc-gh-mparmar

.github/labeler.yml

@@ -82,4 +82,6 @@ ALIYUN:
 GCP:
   - gcp/**/*
 DELL:
-  - dell/**/*
+  - dell/**/*
+SNOWFLAKE:
+  - snowflake/**/*

build.gradle

@@ -682,6 +682,22 @@ project(':iceberg-dell') {
   }
 }
 
+project(':iceberg-snowflake') {
+  dependencies {
+    implementation project(':iceberg-core')
+    implementation project(':iceberg-common')
+    implementation project(path: ':iceberg-bundled-guava', configuration: 'shadow')
+    implementation project(':iceberg-aws')
+    implementation "com.fasterxml.jackson.core:jackson-databind"
+    implementation "com.fasterxml.jackson.core:jackson-core"
+    implementation "commons-dbutils:commons-dbutils:1.7"
+
+    runtimeOnly("net.snowflake:snowflake-jdbc:3.13.22")
+
+    testImplementation project(path: ':iceberg-core', configuration: 'testArtifacts')
+  }
+}
+
 @Memoized
 boolean versionFileExists() {
   return file('version.txt').exists()

core/src/main/java/org/apache/iceberg/jdbc/JdbcClientPool.java

@@ -27,12 +27,12 @@
 import org.apache.iceberg.CatalogProperties;
 import org.apache.iceberg.ClientPoolImpl;
 
-class JdbcClientPool extends ClientPoolImpl<Connection, SQLException> {
+public class JdbcClientPool extends ClientPoolImpl<Connection, SQLException> {
 
   private final String dbUrl;
   private final Map<String, String> properties;
 
-  JdbcClientPool(String dbUrl, Map<String, String> props) {
+  public JdbcClientPool(String dbUrl, Map<String, String> props) {
     this(
         Integer.parseInt(
             props.getOrDefault(
@@ -42,7 +42,7 @@ class JdbcClientPool extends ClientPoolImpl<Connection, SQLException> {
         props);
   }
 
-  JdbcClientPool(int poolSize, String dbUrl, Map<String, String> props) {
+  public JdbcClientPool(int poolSize, String dbUrl, Map<String, String> props) {
     super(poolSize, SQLNonTransientConnectionException.class, true);
     properties = props;
     this.dbUrl = dbUrl;

settings.gradle

@@ -34,6 +34,7 @@ include 'hive-metastore'
 include 'nessie'
 include 'gcp'
 include 'dell'
+include 'snowflake'
 
 project(':api').name = 'iceberg-api'
 project(':common').name = 'iceberg-common'
@@ -51,6 +52,7 @@ project(':hive-metastore').name = 'iceberg-hive-metastore'
 project(':nessie').name = 'iceberg-nessie'
 project(':gcp').name = 'iceberg-gcp'
 project(':dell').name = 'iceberg-dell'
+project(':snowflake').name = 'iceberg-snowflake'
 
 List<String> knownFlinkVersions = System.getProperty("knownFlinkVersions").split(",")
 String flinkVersionsString = System.getProperty("flinkVersions") != null ? System.getProperty("flinkVersions") : System.getProperty("defaultFlinkVersions")

snowflake/src/main/java/org/apache/iceberg/snowflake/JdbcSnowflakeClient.java

@@ -0,0 +1,158 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.iceberg.snowflake;
+
+import java.sql.SQLException;
+import java.util.List;
+import org.apache.commons.dbutils.QueryRunner;
+import org.apache.iceberg.catalog.Namespace;
+import org.apache.iceberg.catalog.TableIdentifier;
+import org.apache.iceberg.jdbc.JdbcClientPool;
+import org.apache.iceberg.jdbc.UncheckedInterruptedException;
+import org.apache.iceberg.jdbc.UncheckedSQLException;
+import org.apache.iceberg.snowflake.entities.SnowflakeSchema;
+import org.apache.iceberg.snowflake.entities.SnowflakeTable;
+import org.apache.iceberg.snowflake.entities.SnowflakeTableMetadata;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This implementation of SnowflakeClient builds on top of Snowflake's JDBC driver to interact with
+ * Snowflake's Iceberg-aware resource model. Despite using JDBC libraries, the resource model is
+ * derived from Snowflake's own first-class support for Iceberg tables as opposed to using an opaque
+ * JDBC layer to store Iceberg metadata itself in an Iceberg-agnostic database.
+ *
+ * <p>This thus differs from the JdbcCatalog in that Snowflake's service provides the source of
+ * truth of Iceberg metadata, rather than serving as a storage layer for a client-defined Iceberg
+ * resource model.
+ */
+public class JdbcSnowflakeClient implements SnowflakeClient {
+  public static final String EXPECTED_JDBC_IMPL = "net.snowflake.client.jdbc.SnowflakeDriver";
+
+  private static final Logger LOG = LoggerFactory.getLogger(JdbcSnowflakeClient.class);
+  private final JdbcClientPool connectionPool;
+
+  JdbcSnowflakeClient(JdbcClientPool conn) {
+    connectionPool = conn;
+  }
+
+  @Override
+  public List<SnowflakeSchema> listSchemas(Namespace namespace) {
+    StringBuilder baseQuery = new StringBuilder("SHOW SCHEMAS");
+    Object[] queryParams = null;
+    if (namespace == null || namespace.isEmpty()) {
+      // for empty or null namespace search for all schemas at account level where the user
+      // has access to list.
+      baseQuery.append(" IN ACCOUNT");
+    } else {
+      // otherwise restrict listing of schema within the database.
+      baseQuery.append(" IN DATABASE IDENTIFIER(?)");
+      queryParams = new Object[] {namespace.level(SnowflakeResources.NAMESPACE_DB_LEVEL - 1)};
+    }
+
+    final String finalQuery = baseQuery.toString();
+    final Object[] finalQueryParams = queryParams;
+    QueryRunner run = new QueryRunner(true);
+    List<SnowflakeSchema> schemas;
+    try {
+      schemas =
+          connectionPool.run(
+              conn ->
+                  run.query(conn, finalQuery, SnowflakeSchema.createHandler(), finalQueryParams));
+    } catch (SQLException e) {
+      throw new UncheckedSQLException(
+          e,
+          "Failed to list schemas for namespace %s",
+          namespace != null ? namespace.toString() : "");
+    } catch (InterruptedException e) {
+      throw new UncheckedInterruptedException(e, "Interrupted while listing schemas");
+    }
+    return schemas;
+  }
+
+  @Override
+  public List<SnowflakeTable> listIcebergTables(Namespace namespace) {
+    StringBuilder baseQuery = new StringBuilder("SHOW ICEBERG TABLES");
+    Object[] queryParams = null;
+    if (namespace.length() == SnowflakeResources.MAX_NAMESPACE_DEPTH) {
+      // For two level namespace, search for iceberg tables within the given schema.
+      baseQuery.append(" IN SCHEMA IDENTIFIER(?)");
+      queryParams =
+          new Object[] {
+            String.format(
+                "%s.%s",
+                namespace.level(SnowflakeResources.NAMESPACE_DB_LEVEL - 1),
+                namespace.level(SnowflakeResources.NAMESPACE_SCHEMA_LEVEL - 1))
+          };
+    } else if (namespace.length() == SnowflakeResources.NAMESPACE_DB_LEVEL) {
+      // For one level namespace, search for iceberg tables within the given database.
+      baseQuery.append(" IN DATABASE IDENTIFIER(?)");
+      queryParams = new Object[] {namespace.level(SnowflakeResources.NAMESPACE_DB_LEVEL - 1)};
+    } else {
+      // For empty or db level namespace, search at account level.
+      baseQuery.append(" IN ACCOUNT");
+    }
+
+    final String finalQuery = baseQuery.toString();
+    final Object[] finalQueryParams = queryParams;
+    QueryRunner run = new QueryRunner(true);
+    List<SnowflakeTable> tables;
+    try {
+      tables =
+          connectionPool.run(
+              conn ->
+                  run.query(conn, finalQuery, SnowflakeTable.createHandler(), finalQueryParams));
+    } catch (SQLException e) {
+      throw new UncheckedSQLException(
+          e, "Failed to list tables for namespace %s", namespace.toString());
+    } catch (InterruptedException e) {
+      throw new UncheckedInterruptedException(e, "Interrupted while listing tables");
+    }
+    return tables;
+  }
+
+  @Override
+  public SnowflakeTableMetadata getTableMetadata(TableIdentifier tableIdentifier) {
+    QueryRunner run = new QueryRunner(true);
+
+    SnowflakeTableMetadata tableMeta;
+    try {
+      final String finalQuery = "SELECT SYSTEM$GET_ICEBERG_TABLE_INFORMATION(?) AS METADATA";
+      tableMeta =
+          connectionPool.run(
+              conn ->
+                  run.query(
+                      conn,
+                      finalQuery,
+                      SnowflakeTableMetadata.createHandler(),
+                      tableIdentifier.toString()));
+    } catch (SQLException e) {
+      throw new UncheckedSQLException(
+          e, "Failed to get table metadata for %s", tableIdentifier.toString());
+    } catch (InterruptedException e) {
+      throw new UncheckedInterruptedException(e, "Interrupted while getting table metadata");
+    }
+    return tableMeta;
+  }
+
+  @Override
+  public void close() {
+    connectionPool.close();
+  }
+}