Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/21306#discussion_r200639540
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/sources/v2/catalog/TableCatalog.java
---
@@ -0,0 +1,123 @@
+/*
+ * 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.sources.v2.catalog;
+
+import org.apache.spark.sql.catalyst.TableIdentifier;
+import org.apache.spark.sql.catalyst.analysis.NoSuchTableException;
+import org.apache.spark.sql.catalyst.analysis.TableAlreadyExistsException;
+import org.apache.spark.sql.catalyst.expressions.Expression;
+import org.apache.spark.sql.types.StructType;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+public interface TableCatalog {
+ /**
+ * Load table metadata by {@link TableIdentifier identifier} from the
catalog.
+ *
+ * @param ident a table identifier
+ * @return the table's metadata
+ * @throws NoSuchTableException If the table doesn't exist.
+ */
+ Table loadTable(TableIdentifier ident) throws NoSuchTableException;
+
+ /**
+ * Create a table in the catalog.
+ *
+ * @param ident a table identifier
+ * @param schema the schema of the new table, as a struct type
+ * @return metadata for the new table
+ * @throws TableAlreadyExistsException If a table already exists for the
identifier
+ */
+ default Table createTable(TableIdentifier ident,
+ StructType schema) throws
TableAlreadyExistsException {
+ return createTable(ident, schema, Collections.emptyList(),
Collections.emptyMap());
+ }
+
+ /**
+ * Create a table in the catalog.
+ *
+ * @param ident a table identifier
+ * @param schema the schema of the new table, as a struct type
+ * @param properties a string map of table properties
+ * @return metadata for the new table
+ * @throws TableAlreadyExistsException If a table already exists for the
identifier
+ */
+ default Table createTable(TableIdentifier ident,
+ StructType schema,
+ Map<String, String> properties) throws
TableAlreadyExistsException {
+ return createTable(ident, schema, Collections.emptyList(), properties);
+ }
+
+ /**
+ * Create a table in the catalog.
+ *
+ * @param ident a table identifier
+ * @param schema the schema of the new table, as a struct type
+ * @param partitions a list of expressions to use for partitioning data
in the table
+ * @param properties a string map of table properties
+ * @return metadata for the new table
+ * @throws TableAlreadyExistsException If a table already exists for the
identifier
+ */
+ Table createTable(TableIdentifier ident,
+ StructType schema,
+ List<Expression> partitions,
--- End diff --
I read the SPIP but I still can't figure it out. How can Spark pass these
"partition transform" to data source? The current end-user API only allows
users to specify partition columns.
And why does the "partition transform" belong to a table definition? I
think it's reasonable to say that a table is partition by column `timestamp`,
and supports pushing partition predicates like `year(timestamp) > 2000`.
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