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https://issues.apache.org/jira/browse/DRILL-4514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15205360#comment-15205360
]
ASF GitHub Bot commented on DRILL-4514:
---------------------------------------
Github user hnfgns commented on a diff in the pull request:
https://github.com/apache/drill/pull/436#discussion_r56915385
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/sql/parser/SqlDescribeSchema.java
---
@@ -0,0 +1,82 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.drill.exec.planner.sql.parser;
+
+import org.apache.calcite.sql.SqlCall;
+import org.apache.calcite.sql.SqlIdentifier;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.SqlLiteral;
+import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.SqlOperator;
+import org.apache.calcite.sql.SqlSpecialOperator;
+import org.apache.calcite.sql.SqlWriter;
+import org.apache.calcite.sql.parser.SqlParserPos;
+import org.apache.drill.exec.planner.sql.handlers.AbstractSqlHandler;
+import org.apache.drill.exec.planner.sql.handlers.DescribeSchemaHandler;
+import org.apache.drill.exec.planner.sql.handlers.SqlHandlerConfig;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Sql parse tree node to represent statement:
+ * SHOW FILES [{FROM | IN} db_name] [LIKE 'pattern' | WHERE expr]
+ */
+public class SqlDescribeSchema extends DrillSqlCall {
+
+ private final SqlIdentifier schema;
+
+ public static final SqlSpecialOperator OPERATOR =
+ new SqlSpecialOperator("DESCRIBE_SCHEMA", SqlKind.OTHER) {
+ @Override
+ public SqlCall createCall(SqlLiteral functionQualifier,
SqlParserPos pos, SqlNode... operands) {
+ return new SqlDescribeSchema(pos, (SqlIdentifier) operands[0]);
+ }
+ };
+
+ public SqlDescribeSchema(SqlParserPos pos, SqlIdentifier schema) {
+ super(pos);
+ this.schema = schema;
+ assert schema != null;
--- End diff --
Sure. I meant we should likely use an explicit null-checking pattern like
`this.schema = Preconditions.checkNotNull(schema, "msg")` instead of an
assertion here.
ps: Guava's Preconditions.
> Add describe schema <schema_name> command
> -----------------------------------------
>
> Key: DRILL-4514
> URL: https://issues.apache.org/jira/browse/DRILL-4514
> Project: Apache Drill
> Issue Type: New Feature
> Affects Versions: Future
> Reporter: Arina Ielchiieva
> Assignee: Arina Ielchiieva
>
> Add describe database <db_name> command which will return directory
> associated with a database on the fly.
> Syntax:
> describe database <db_name>
> describe schema <schema_name>
> Output:
> {noformat}
> DESCRIBE SCHEMA xdf.proc;
> +---------------------+----------------------------+
> | name | location |
> +---------------------+----------------------------+
> | xdf.proc | maprfs://dl.data/processed |
> +---------------------+----------------------------+
> {noformat}
> Current implementation covers only dfs schema.
> For all other "<INFORMATION UNAVAILABLE>" will be returned.
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