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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4729) Add support for prepared statement implementation on server side
Date Mon, 08 Aug 2016 18:35:21 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15412232#comment-15412232

ASF GitHub Bot commented on DRILL-4729:

Github user sudheeshkatkam commented on a diff in the pull request:

    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/work/prepare/PreparedStatementProvider.java
    @@ -0,0 +1,419 @@
    + * 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.work.prepare;
    +import org.apache.drill.common.exceptions.ErrorHelper;
    +import org.apache.drill.common.types.TypeProtos.DataMode;
    +import org.apache.drill.common.types.TypeProtos.MajorType;
    +import org.apache.drill.common.types.TypeProtos.MinorType;
    +import org.apache.drill.common.types.Types;
    +import org.apache.drill.exec.physical.impl.materialize.QueryWritableBatch;
    +import org.apache.drill.exec.proto.ExecProtos.ServerPreparedStatementState;
    +import org.apache.drill.exec.proto.GeneralRPCProtos.Ack;
    +import org.apache.drill.exec.proto.UserBitShared.DrillPBError;
    +import org.apache.drill.exec.proto.UserBitShared.DrillPBError.ErrorType;
    +import org.apache.drill.exec.proto.UserBitShared.QueryId;
    +import org.apache.drill.exec.proto.UserBitShared.QueryResult;
    +import org.apache.drill.exec.proto.UserBitShared.QueryResult.QueryState;
    +import org.apache.drill.exec.proto.UserBitShared.QueryType;
    +import org.apache.drill.exec.proto.UserBitShared.SerializedField;
    +import org.apache.drill.exec.proto.UserProtos.ColumnSearchability;
    +import org.apache.drill.exec.proto.UserProtos.ColumnUpdatability;
    +import org.apache.drill.exec.proto.UserProtos.CreatePreparedStatementReq;
    +import org.apache.drill.exec.proto.UserProtos.CreatePreparedStatementResp;
    +import org.apache.drill.exec.proto.UserProtos.PreparedStatement;
    +import org.apache.drill.exec.proto.UserProtos.PreparedStatementHandle;
    +import org.apache.drill.exec.proto.UserProtos.RequestStatus;
    +import org.apache.drill.exec.proto.UserProtos.ResultColumnMetadata;
    +import org.apache.drill.exec.proto.UserProtos.RpcType;
    +import org.apache.drill.exec.proto.UserProtos.RunQuery;
    +import org.apache.drill.exec.rpc.Acks;
    +import org.apache.drill.exec.rpc.Response;
    +import org.apache.drill.exec.rpc.ResponseSender;
    +import org.apache.drill.exec.rpc.RpcOutcomeListener;
    +import org.apache.drill.exec.rpc.user.UserServer.UserClientConnection;
    +import org.apache.drill.exec.rpc.user.UserSession;
    +import org.apache.drill.exec.store.ischema.InfoSchemaConstants;
    +import org.apache.drill.exec.work.user.UserWorker;
    +import org.joda.time.Period;
    +import com.google.common.collect.ImmutableMap;
    +import io.netty.buffer.ByteBuf;
    +import io.netty.channel.ChannelFuture;
    +import java.math.BigDecimal;
    +import java.net.SocketAddress;
    +import java.sql.Date;
    +import java.sql.ResultSetMetaData;
    +import java.sql.Time;
    +import java.sql.Timestamp;
    +import java.util.List;
    +import java.util.Map;
    +import java.util.UUID;
    +import java.util.concurrent.CountDownLatch;
    +import java.util.concurrent.TimeUnit;
    + * Contains worker {@link Runnable} for creating a prepared statement and helper methods.
    + */
    +public class PreparedStatementProvider {
    +  private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(PreparedStatementProvider.class);
    +  private static final int LIMIT_0_QUERY_TIMEOUT_MINS = 10;
    --- End diff --
    Or make this a system property?
    We have seen cases where `LIMIT 0` queries take longer than 10 minutes. Although there
is [an option (disabled by default)](https://issues.apache.org/jira/browse/DRILL-3623) to
avoid full-fledged execution for queries on _tables with known schema_, on other tables, `LIMIT
0` queries may take 10 minutes. They should not, but they may (due to single fragment execution).

> Add support for prepared statement implementation on server side
> ----------------------------------------------------------------
>                 Key: DRILL-4729
>                 URL: https://issues.apache.org/jira/browse/DRILL-4729
>             Project: Apache Drill
>          Issue Type: Sub-task
>          Components: Metadata
>            Reporter: Venki Korukanti
>            Assignee: Venki Korukanti
>             Fix For: 1.8.0
> Currently Drill JDBC/ODBC driver implements its own prepared statement implementation,
which basically issues limit 0 query to get the metadata and then executes the actual query.
So the query is planned twice (for metadata fetch and actual execution). Proposal is to move
that logic to server where we can make optimizations without disrupting/updating the JDBC/ODBC
> *  {{PreparedStatement createPreparedStatement(String query)}}. {{PreparedStatement}}
object contains the following:
> ** {{ResultSetMetadata getResultSetMetadata()}}
> *** {{ResultsSetMetadata}} contains methods to fetch info about output columns of the
query. What info these methods provide is given in this [spreadsheet|https://docs.google.com/spreadsheets/d/1A6nqUQo5xJaZDQlDTittpVrK7t4Kylycs3P32Yn_O5k/edit?usp=sharing].
It lists the ODBC/JDBC requirements and what Drill will provided through object {{ResultsSetMetadata}}.
> *** Server can put more info here which is opaque to client and use it in server when
the client sends execute prepared statement query request. 
> Overload the current submit query API to take the {{PreparedStatement}} returned above.

> In the initial implementation, server side implementation of {{createPreparedStatement}}
API is implemented as follows:
> * Runs the query with {{LIMIT 0}}, gets the schema
> * Convert the query into a binary blob and set it as opaque object in {{PreparedStatement}}.
> When the {{PreparedStatement}} is submitted for execution, reconstruct the query from
binary blob in opaque component of {{PreparedStatement}} and execute it from scratch. 
> Opaque component of the {{PreparedStatement}} is where we can save more information which
we can use for optimizations/speedups.
> NOTE: We are not going to worry about parameters in prepared query in initial implementation.
We can provide the functionality later if there is sufficient demand from Drill community.
> Changes in this patch are going to include protobuf messages, server side messages and
Java client APIs. Native client changes are going to be tracked in a separate JIRA.

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