Github user dongjoon-hyun commented on a diff in the pull request:
https://github.com/apache/spark/pull/21306#discussion_r205585462
--- Diff:
sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/CatalogProvider.java
---
@@ -0,0 +1,50 @@
+/*
+ * 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.spark.sql.catalog.v2;
+
+import org.apache.spark.sql.internal.SQLConf;
+
+/**
+ * A marker interface to provide a catalog implementation for Spark.
+ * <p>
+ * Implementations can provide catalog functions by implementing
additional interfaces, like
+ * {@link TableCatalog} to expose table operations.
+ * <p>
+ * Catalog implementations must implement this marker interface to be
loaded by
+ * {@link Catalogs#load(String, SQLConf)}. The loader will instantiate
catalog classes using the
+ * required public no-arg constructor. After creating an instance, it will
be configured by calling
+ * {@link #initialize(CaseInsensitiveStringMap)}.
+ * <p>
+ * Catalog implementations are registered to a name by adding a
configuration option to Spark:
+ * {@code spark.sql.catalog.catalog-name=com.example.YourCatalogClass}.
All configuration properties
+ * in the Spark configuration that share the catalog name prefix,
+ * {@code spark.sql.catalog.catalog-name.(key)=(value)} will be passed in
the case insensitive
+ * string map of options in initialization with the prefix removed. An
additional property,
+ * {@code name}, is also added to the options and will contain the
catalog's name; in this case,
+ * "catalog-name".
+ */
+public interface CatalogProvider {
+ /**
+ * Called to initialize configuration.
+ * <p>
+ * This method is called once, just after the provider is instantiated.
+ *
+ * @param options a case-insensitive string map of configuration
+ */
+ void initialize(CaseInsensitiveStringMap options);
--- End diff --
Got it. Thanks!
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