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From bbende <...@git.apache.org>
Subject [GitHub] nifi pull request: NIFI-981: Added ExecuteHiveQL and PutHiveQL pro...
Date Wed, 27 Apr 2016 18:56:19 GMT
Github user bbende commented on a diff in the pull request:

    https://github.com/apache/nifi/pull/384#discussion_r61316112
  
    --- Diff: nifi-nar-bundles/nifi-hive-bundle/nifi-hive-processors/src/main/java/org/apache/nifi/processors/hive/ExecuteHiveQL.java
---
    @@ -0,0 +1,178 @@
    +/*
    + * 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.nifi.processors.hive;
    +
    +import org.apache.nifi.annotation.behavior.EventDriven;
    +import org.apache.nifi.annotation.behavior.InputRequirement;
    +import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
    +import org.apache.nifi.annotation.documentation.CapabilityDescription;
    +import org.apache.nifi.annotation.documentation.Tags;
    +import org.apache.nifi.components.PropertyDescriptor;
    +import org.apache.nifi.dbcp.hive.HiveDBCPService;
    +import org.apache.nifi.flowfile.FlowFile;
    +import org.apache.nifi.logging.ProcessorLog;
    +import org.apache.nifi.processor.ProcessContext;
    +import org.apache.nifi.processor.ProcessSession;
    +import org.apache.nifi.processor.Relationship;
    +import org.apache.nifi.processor.exception.ProcessException;
    +import org.apache.nifi.processor.io.OutputStreamCallback;
    +import org.apache.nifi.processor.util.StandardValidators;
    +import org.apache.nifi.util.LongHolder;
    +import org.apache.nifi.util.StopWatch;
    +import org.apache.nifi.util.hive.HiveJdbcCommon;
    +
    +import java.io.IOException;
    +import java.io.OutputStream;
    +import java.sql.Connection;
    +import java.sql.ResultSet;
    +import java.sql.SQLException;
    +import java.sql.Statement;
    +import java.util.ArrayList;
    +import java.util.Collections;
    +import java.util.HashSet;
    +import java.util.List;
    +import java.util.Set;
    +import java.util.concurrent.TimeUnit;
    +
    +@EventDriven
    +@InputRequirement(Requirement.INPUT_ALLOWED)
    +@Tags({"hive", "sql", "select", "jdbc", "query", "database"})
    +@CapabilityDescription("Execute provided HiveQL SELECT query against a Hive database
connection. Query result will be converted to Avro format."
    +        + " Streaming is used so arbitrarily large result sets are supported. This processor
can be scheduled to run on "
    +        + "a timer, or cron expression, using the standard scheduling methods, or it
can be triggered by an incoming FlowFile. "
    +        + "If it is triggered by an incoming FlowFile, then attributes of that FlowFile
will be available when evaluating the "
    +        + "select query. FlowFile attribute 'executehiveql.row.count' indicates how many
rows were selected.")
    +public class ExecuteHiveQL extends AbstractHiveQLProcessor {
    +
    +    public static final String RESULT_ROW_COUNT = "executehiveql.row.count";
    +
    +    // Relationships
    +    public static final Relationship REL_SUCCESS = new Relationship.Builder()
    +            .name("success")
    +            .description("Successfully created FlowFile from HiveQL query result set.")
    +            .build();
    +    public static final Relationship REL_FAILURE = new Relationship.Builder()
    +            .name("failure")
    +            .description("HiveQL query execution failed. Incoming FlowFile will be penalized
and routed to this relationship")
    +            .build();
    +
    +
    +    public static final PropertyDescriptor HIVEQL_SELECT_QUERY = new PropertyDescriptor.Builder()
    +            .name("hive-query")
    +            .displayName("HiveQL select query")
    +            .description("HiveQL select query")
    +            .required(true)
    +            .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
    +            .expressionLanguageSupported(true)
    +            .build();
    +
    +    private final static List<PropertyDescriptor> propertyDescriptors;
    +    private final static Set<Relationship> relationships;
    +
    +    /*
    +     * Will ensure that the list of property descriptors is build only once.
    +     * Will also create a Set of relationships
    +     */
    +    static {
    +        List<PropertyDescriptor> _propertyDescriptors = new ArrayList<>();
    +        _propertyDescriptors.add(HIVE_DBCP_SERVICE);
    +        _propertyDescriptors.add(HIVEQL_SELECT_QUERY);
    +        propertyDescriptors = Collections.unmodifiableList(_propertyDescriptors);
    +
    +        Set<Relationship> _relationships = new HashSet<>();
    +        _relationships.add(REL_SUCCESS);
    +        _relationships.add(REL_FAILURE);
    +        relationships = Collections.unmodifiableSet(_relationships);
    +    }
    +
    +    @Override
    +    protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
    +        return propertyDescriptors;
    +    }
    +
    +    @Override
    +    public Set<Relationship> getRelationships() {
    +        return relationships;
    +    }
    +
    +    @Override
    +    public void onTrigger(final ProcessContext context, final ProcessSession session)
throws ProcessException {
    +        FlowFile fileToProcess = null;
    +        if (context.hasIncomingConnection()) {
    +            fileToProcess = session.get();
    +
    +            // If we have no FlowFile, and all incoming connections are self-loops then
we can continue on.
    +            // However, if we have no FlowFile and we have connections coming from other
Processors, then
    +            // we know that we should run only if we have a FlowFile.
    +            if (fileToProcess == null && context.hasNonLoopConnection()) {
    +                return;
    +            }
    +        }
    +
    +        final ProcessorLog logger = getLogger();
    +        final HiveDBCPService dbcpService = context.getProperty(HIVE_DBCP_SERVICE).asControllerService(HiveDBCPService.class);
    +        final String selectQuery = context.getProperty(HIVEQL_SELECT_QUERY).evaluateAttributeExpressions(fileToProcess).getValue();
    +        final StopWatch stopWatch = new StopWatch(true);
    +
    +        try (final Connection con = dbcpService.getConnection();
    +            final Statement st = con.createStatement()) {
    +            final LongHolder nrOfRows = new LongHolder(0L);
    +            if (fileToProcess == null) {
    +                fileToProcess = session.create();
    +            }
    +            fileToProcess = session.write(fileToProcess, new OutputStreamCallback() {
    +                @Override
    +                public void process(final OutputStream out) throws IOException {
    +                    try {
    +                        logger.debug("Executing query {}", new Object[]{selectQuery});
    +                        final ResultSet resultSet = st.executeQuery(selectQuery);
    +                        nrOfRows.set(HiveJdbcCommon.convertToAvroStream(resultSet, out));
    +                    } catch (final SQLException e) {
    +                        throw new ProcessException(e);
    +                    }
    +                }
    +            });
    +
    +            // set attribute how many rows were selected
    +            fileToProcess = session.putAttribute(fileToProcess, RESULT_ROW_COUNT, nrOfRows.get().toString());
    +
    +            logger.info("{} contains {} Avro records; transferring to 'success'",
    +                    new Object[]{fileToProcess, nrOfRows.get()});
    +            session.getProvenanceReporter().modifyContent(fileToProcess, "Retrieved "
+ nrOfRows.get() + " rows",
    --- End diff --
    
    What do you think about having different provenance events based on whether or not there
was an incoming flow file? 
    
    If fileToProcess was null and we called session.create() we might want this to be a receive
event with the uri of the Hive instance we pulled from, but if we had an incoming FlowFile
and overwrote the content then we probably want modifyContent


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