[GitHub] [arrow] jduo commented on a change in pull request #9368: [WIP] [POC] Flight SQL

[GitBox <gi...@apache.org>]

jduo commented on a change in pull request #9368:
URL: https://github.com/apache/arrow/pull/9368#discussion_r664909672



##########
File path: java/flight/flight-sql/src/main/java/org/apache/arrow/flight/sql/FlightSqlClientUtils.java
##########
@@ -0,0 +1,206 @@
+/*
+ * 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.arrow.flight.sql;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Iterator;
+import java.util.List;
+
+import org.apache.arrow.flight.Action;
+import org.apache.arrow.flight.FlightClient;
+import org.apache.arrow.flight.FlightDescriptor;
+import org.apache.arrow.flight.FlightInfo;
+import org.apache.arrow.flight.Result;
+import org.apache.arrow.flight.sql.impl.FlightSql;
+import org.apache.arrow.flight.sql.impl.FlightSql.ActionCreatePreparedStatementResult;
+import org.apache.arrow.flight.sql.impl.FlightSql.CommandPreparedStatementQuery;
+import org.apache.arrow.vector.types.pojo.Schema;
+
+import com.google.protobuf.Any;
+import com.google.protobuf.ByteString;
+
+import io.grpc.Status;
+
+/**
+ * Client side utilities to work with Flight SQL semantics.
+ */
+public final class FlightSqlClientUtils {
+
+  /**
+   * Helper method to request a list of tables from a Flight SQL enabled endpoint.
+   *
+   * @param client              The Flight Client.
+   * @param catalog             The catalog.
+   * @param schemaFilterPattern The schema filter pattern.
+   * @param tableFilterPattern  The table filter pattern.
+   * @param tableTypes          The table types to include.
+   * @param includeSchema       True to include the schema upon return, false to not include the schema.
+   * @return a FlightInfo object representing the stream(s) to fetch.
+   */
+  public static FlightInfo getTables(FlightClient client, String catalog, String schemaFilterPattern,
+          String tableFilterPattern, List<String> tableTypes, boolean includeSchema) {
+
+    final FlightSql.CommandGetTables.Builder builder = FlightSql.CommandGetTables.newBuilder();
+
+    if (catalog != null) {
+      builder.setCatalog(catalog);
+    }
+
+    if (schemaFilterPattern != null) {
+      builder.setSchemaFilterPattern(schemaFilterPattern);
+    }
+
+    if (tableFilterPattern != null) {
+      builder.setTableNameFilterPattern(tableFilterPattern);
+    }
+
+    if (tableTypes != null) {
+      builder.addAllTableTypes(tableTypes);
+    }
+    builder.setIncludeSchema(includeSchema);
+
+    final FlightDescriptor descriptor = FlightDescriptor.command(Any.pack(builder.build()).toByteArray());
+    return client.getInfo(descriptor);
+  }
+
+  /**
+   * Helper method to create a prepared statement on the server.
+   *
+   * @param client The Flight Client.
+   * @param query  The query to prepare.
+   * @return Metadata and handles to the prepared statement which exists on the server.
+   */
+  public static FlightSqlPreparedStatement getPreparedStatement(FlightClient client, String query) {
+    return new FlightSqlPreparedStatement(client, query);
+  }
+
+  /**
+   * Helper class to encapsulate Flight SQL prepared statement logic.
+   */
+  public static class FlightSqlPreparedStatement implements Closeable {
+    private final FlightClient client;
+    private final ActionCreatePreparedStatementResult preparedStatementResult;
+    private long invocationCount;
+    private boolean isClosed;
+    private Schema resultSetSchema = null;
+    private Schema parameterSchema = null;
+
+    /**
+     * Constructor.
+     *
+     * @param client The client. FlightSqlPreparedStatement does not maintain this resource.
+     * @param sql    The query.
+     */
+    public FlightSqlPreparedStatement(FlightClient client, String sql) {
+      this.client = client;
+
+      final Iterator<Result> preparedStatementResults = client.doAction(new Action("GetPreparedStatement",
+              Any.pack(FlightSql.ActionCreatePreparedStatementRequest
+                      .newBuilder()
+                      .setQuery(sql)
+                      .build())
+                      .toByteArray()));
+
+      preparedStatementResult = FlightSqlUtils.unpackAndParseOrThrow(
+              preparedStatementResults.next().getBody(),
+              ActionCreatePreparedStatementResult.class);
+
+      invocationCount = 0;
+      isClosed = false;
+    }
+
+    /**
+     * Returns the Schema of the resultset.
+     *
+     * @return the Schema of the resultset.
+     */
+    public Schema getResultSetSchema() {
+      if (resultSetSchema == null && preparedStatementResult.getDatasetSchema() != null) {
+        resultSetSchema = Schema.deserialize(preparedStatementResult.getDatasetSchema().asReadOnlyByteBuffer());
+      }
+      return resultSetSchema;
+    }
+
+    /**
+     * Returns the Schema of the parameters.
+     *
+     * @return the Schema of the parameters.
+     */
+    public Schema getParameterSchema() {
+      if (parameterSchema == null && preparedStatementResult.getParameterSchema() != null) {
+        parameterSchema = Schema.deserialize(preparedStatementResult.getParameterSchema().asReadOnlyByteBuffer());
+      }
+      return parameterSchema;
+    }
+
+    /**
+     * Executes the prepared statement query on the server.
+     *
+     * @return a FlightInfo object representing the stream(s) to fetch.
+     * @throws IOException if the PreparedStatement is closed.
+     */
+    public FlightInfo executeQuery() throws IOException {
+      if (isClosed) {
+        throw new IOException("Prepared statement has already been closed on the server.");

Review comment:
       Nit: This isn't an IO error and is more of an IllegalStateException.




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