[GitHub] vvysotskyi commented on a change in pull request #1430: DRILL-6680: Expose show files command into INFORMATION_SCHEMA

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vvysotskyi commented on a change in pull request #1430: DRILL-6680: Expose show files command into INFORMATION_SCHEMA
URL: https://github.com/apache/drill/pull/1430#discussion_r209544436
 
 

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 File path: exec/java-exec/src/main/java/org/apache/drill/exec/planner/sql/handlers/ShowFilesHandler.java
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+/*
+ * 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.drill.exec.planner.sql.handlers;
+
+import org.apache.calcite.schema.SchemaPlus;
+import org.apache.calcite.sql.SqlIdentifier;
+import org.apache.calcite.sql.SqlLiteral;
+import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.SqlNodeList;
+import org.apache.calcite.sql.SqlSelect;
+import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.sql.parser.SqlParserPos;
+import org.apache.calcite.util.Util;
+import org.apache.drill.common.exceptions.UserException;
+import org.apache.drill.exec.planner.sql.SchemaUtilites;
+import org.apache.drill.exec.planner.sql.parser.DrillParserUtil;
+import org.apache.drill.exec.planner.sql.parser.SqlShowFiles;
+import org.apache.drill.exec.store.AbstractSchema;
+import org.apache.drill.exec.store.dfs.WorkspaceSchemaFactory.WorkspaceSchema;
+import org.apache.drill.exec.store.ischema.InfoSchemaTableType;
+import org.apache.drill.exec.work.foreman.ForemanSetupException;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.apache.drill.exec.store.ischema.InfoSchemaConstants.FILES_COL_RELATIVE_PATH;
+import static org.apache.drill.exec.store.ischema.InfoSchemaConstants.FILES_COL_SCHEMA_NAME;
+import static org.apache.drill.exec.store.ischema.InfoSchemaConstants.IS_SCHEMA_NAME;
+
+
+public class ShowFilesHandler extends DefaultSqlHandler {
+  private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(SetOptionHandler.class);
+
+  public ShowFilesHandler(SqlHandlerConfig config) {
+    super(config);
+  }
+
+  /** Rewrite the parse tree as SELECT ... FROM INFORMATION_SCHEMA.FILES ... */
+  @Override
+  public SqlNode rewrite(SqlNode sqlNode) throws ForemanSetupException {
+
+    List<SqlNode> selectList = Collections.singletonList(SqlIdentifier.star(SqlParserPos.ZERO));
+
+    SqlNode fromClause = new SqlIdentifier(
+        Arrays.asList(IS_SCHEMA_NAME, InfoSchemaTableType.FILES.name()), null, SqlParserPos.ZERO, null);
+
+    SchemaPlus defaultSchema = config.getConverter().getDefaultSchema();
+    SchemaPlus drillSchema = defaultSchema;
+
+    SqlShowFiles showFiles = unwrap(sqlNode, SqlShowFiles.class);
+    SqlIdentifier from = showFiles.getDb();
+    boolean addRelativePathLikeClause = false;
+
+    // Show files can be used without from clause, in which case we display the files in the default schema
+    if (from != null) {
+      // We are not sure if the full from clause is just the schema or includes table name,
+      // first try to see if the full path specified is a schema
+      drillSchema = SchemaUtilites.findSchema(defaultSchema, from.names);
+      if (drillSchema == null) {
+        // Entire from clause is not a schema, try to obtain the schema without the last part of the specified clause.
+        drillSchema = SchemaUtilites.findSchema(defaultSchema, from.names.subList(0, from.names.size() - 1));
+        addRelativePathLikeClause = true;
+      }
+
+      if (drillSchema == null) {
+        throw UserException.validationError()
+            .message("Invalid FROM/IN clause [%s]", from.toString())
+            .build(logger);
+      }
+    }
+
+    WorkspaceSchema wsSchema;
+
+    try {
+      AbstractSchema abstractSchema = drillSchema.unwrap(AbstractSchema.class);
+      if (abstractSchema instanceof WorkspaceSchema) {
 
 Review comment:
   `WorkspaceSchema` uses implementation of `getDefaultSchema()` method from `AbstractSchema` which returns `this` instance. So I think `if` block may be replaced with the statement from `else` branch.

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