Github user markap14 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/261#discussion_r56232288
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/QueryDatabaseTable.java
---
@@ -0,0 +1,608 @@
+/*
+ * 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.standard;
+
+import org.apache.commons.lang3.StringUtils;
+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.behavior.Stateful;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.state.Scope;
+import org.apache.nifi.components.state.StateManager;
+import org.apache.nifi.components.state.StateMap;
+import org.apache.nifi.dbcp.DBCPService;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.logging.ProcessorLog;
+import org.apache.nifi.processor.AbstractSessionFactoryProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.ProcessSessionFactory;
+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.processors.standard.util.JdbcCommon;
+import org.apache.nifi.util.LongHolder;
+import org.apache.nifi.util.StopWatch;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.math.BigDecimal;
+import java.sql.Connection;
+import java.sql.Date;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.sql.Timestamp;
+import java.text.DecimalFormat;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+
+import static java.sql.Types.ARRAY;
+import static java.sql.Types.BIGINT;
+import static java.sql.Types.BINARY;
+import static java.sql.Types.BIT;
+import static java.sql.Types.BLOB;
+import static java.sql.Types.BOOLEAN;
+import static java.sql.Types.CHAR;
+import static java.sql.Types.CLOB;
+import static java.sql.Types.DATE;
+import static java.sql.Types.DECIMAL;
+import static java.sql.Types.DOUBLE;
+import static java.sql.Types.FLOAT;
+import static java.sql.Types.INTEGER;
+import static java.sql.Types.LONGNVARCHAR;
+import static java.sql.Types.LONGVARBINARY;
+import static java.sql.Types.LONGVARCHAR;
+import static java.sql.Types.NCHAR;
+import static java.sql.Types.NUMERIC;
+import static java.sql.Types.NVARCHAR;
+import static java.sql.Types.REAL;
+import static java.sql.Types.ROWID;
+import static java.sql.Types.SMALLINT;
+import static java.sql.Types.TIME;
+import static java.sql.Types.TIMESTAMP;
+import static java.sql.Types.TINYINT;
+import static java.sql.Types.VARBINARY;
+import static java.sql.Types.VARCHAR;
+
+@EventDriven
+@InputRequirement(Requirement.INPUT_FORBIDDEN)
+@Tags({"sql", "select", "jdbc", "query", "database"})
+@CapabilityDescription("Execute provided SQL select query. 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 'querydbtable.row.count'
indicates how many rows were selected.")
+@Stateful(scopes = Scope.CLUSTER, description = "After performing a query
on the specified table, the maximum values for "
+ + "the specified column(s) will be retained for use in future
executions of the query. This allows the Processor "
+ + "to fetch only those records that have max values greater than
the retained values. This can be used for "
+ + "incremental fetching, fetching of newly added rows, etc. To
clear the maximum values, clear the state of the processor "
+ + "per the State Management documentation")
+@WritesAttribute(attribute = "querydbtable.row.count")
+public class QueryDatabaseTable extends AbstractSessionFactoryProcessor {
+
+ public static final String RESULT_ROW_COUNT = "querydbtable.row.count";
+
+ public static final String SQL_PREPROCESS_STRATEGY_NONE = "None";
+ public static final String SQL_PREPROCESS_STRATEGY_ORACLE = "Oracle";
+
+ // Relationships
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("success")
+ .description("Successfully created FlowFile from SQL query
result set.")
+ .build();
+ public static final Relationship REL_FAILURE = new
Relationship.Builder()
+ .name("failure")
+ .description("SQL query execution failed. Incoming FlowFile
will be penalized and routed to this relationship.")
+ .build();
+ private final Set<Relationship> relationships;
+
+ public static final PropertyDescriptor DBCP_SERVICE = new
PropertyDescriptor.Builder()
+ .name("Database Connection Pooling Service")
+ .description("The Controller Service that is used to obtain a
connection to the database.")
+ .required(true)
+ .identifiesControllerService(DBCPService.class)
+ .build();
+
+ public static final PropertyDescriptor TABLE_NAME = new
PropertyDescriptor.Builder()
+ .name("Table Name")
+ .description("The name of the database table to be queried.")
+ .required(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor COLUMN_NAMES = new
PropertyDescriptor.Builder()
+ .name("Columns to Return")
+ .description("A comma-separated list of column names to be
used in the query. If your database requires "
+ + "special treatment of the names (quoting, e.g.),
each name should include such treatment. If no "
+ + "column names are supplied, all columns in the
specified table will be returned.")
+ .required(false)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor MAX_VALUE_COLUMN_NAMES = new
PropertyDescriptor.Builder()
+ .name("Maximum-value Columns")
+ .description("A comma-separated list of column names. The
processor will keep track of the maximum value "
+ + "for each column that has been returned since the
processor started running. This can be used to "
+ + "retrieve only those rows that have been
added/updated since the last retrieval. Note that some "
+ + "JDBC types such as bit/boolean are not conducive to
maintaining maximum value, so columns of these "
+ + "types should not be listed in this property, and
will result in error(s) during processing.")
+ .required(false)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor QUERY_TIMEOUT = new
PropertyDescriptor.Builder()
+ .name("Max Wait Time")
+ .description("The maximum amount of time allowed for a running
SQL select query "
+ + ", zero means there is no limit. Max time less than
1 second will be equal to zero.")
+ .defaultValue("0 seconds")
+ .required(true)
+ .addValidator(StandardValidators.TIME_PERIOD_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor SQL_PREPROCESS_STRATEGY = new
PropertyDescriptor.Builder()
+ .name("SQL Pre-processing Strategy")
+ .description("The strategy to employ when generating the SQL
for querying the table. A strategy may include "
+ + "custom or database-specific code, such as the
treatment of time/date formats.")
+ .required(true)
+ .allowableValues(SQL_PREPROCESS_STRATEGY_NONE,
SQL_PREPROCESS_STRATEGY_ORACLE)
+ .defaultValue("None")
+ .build();
+
+
+ private final List<PropertyDescriptor> propDescriptors;
+
+ protected final Map<String, Integer> columnTypeMap = new HashMap<>();
+
+ public QueryDatabaseTable() {
+ final Set<Relationship> r = new HashSet<>();
+ r.add(REL_SUCCESS);
+ r.add(REL_FAILURE);
+ relationships = Collections.unmodifiableSet(r);
+
+ final List<PropertyDescriptor> pds = new ArrayList<>();
+ pds.add(DBCP_SERVICE);
+ pds.add(TABLE_NAME);
+ pds.add(COLUMN_NAMES);
+ pds.add(MAX_VALUE_COLUMN_NAMES);
+ pds.add(QUERY_TIMEOUT);
+ pds.add(SQL_PREPROCESS_STRATEGY);
+ propDescriptors = Collections.unmodifiableList(pds);
+ }
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return relationships;
+ }
+
+ @Override
+ protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return propDescriptors;
+ }
+
+ @OnScheduled
+ public void setup(final ProcessContext context) {
+ // Try to fill the columnTypeMap with the types of the desired
max-value columns
+ final DBCPService dbcpService =
context.getProperty(DBCP_SERVICE).asControllerService(DBCPService.class);
+ final String tableName =
context.getProperty(TABLE_NAME).getValue();
+ final String maxValueColumnNames =
context.getProperty(MAX_VALUE_COLUMN_NAMES).getValue();
+
+ try (final Connection con = dbcpService.getConnection();
+ final Statement st = con.createStatement()) {
+
+ // Try a query that returns no rows, for the purposes of
getting metadata about the columns. It is possible
+ // to use DatabaseMetaData.getColumns(), but not all drivers
support this, notably the schema-on-read
+ // approach as in Apache Drill
+ String query = getSelectFromClause(tableName,
maxValueColumnNames).append(" WHERE 1 = 0").toString();
+ ResultSet resultSet = st.executeQuery(query);
+ ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
+ int numCols = resultSetMetaData.getColumnCount();
+ if (numCols > 0) {
+ columnTypeMap.clear();
+ for (int i = 1; i <= numCols; i++) {
+ String colName =
resultSetMetaData.getColumnName(i).toLowerCase();
+ int colType = resultSetMetaData.getColumnType(i);
+ columnTypeMap.put(colName, colType);
+ }
+
+ } else {
+ throw new ProcessException("No columns found in table from
those specified: " + maxValueColumnNames);
+ }
+
+ } catch (SQLException e) {
+ throw new ProcessException("Unable to communicate with
database in order to determine column types", e);
+ }
+ }
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSessionFactory sessionFactory) throws ProcessException {
+ ProcessSession session = sessionFactory.createSession();
+ FlowFile fileToProcess = null;
+
+ final ProcessorLog logger = getLogger();
+
+ final DBCPService dbcpService =
context.getProperty(DBCP_SERVICE).asControllerService(DBCPService.class);
+ final String tableName =
context.getProperty(TABLE_NAME).getValue();
+ final String columnNames =
context.getProperty(COLUMN_NAMES).getValue();
+ final String maxValueColumnNames =
context.getProperty(MAX_VALUE_COLUMN_NAMES).getValue();
+ final String preProcessStrategy =
context.getProperty(SQL_PREPROCESS_STRATEGY).getValue();
+ final StateManager stateManager = context.getStateManager();
+ final StateMap stateMap;
+
+ try {
+ stateMap = stateManager.getState(Scope.CLUSTER);
+ } catch (final IOException ioe) {
+ getLogger().error("Failed to retrieve observed maximum values
from the State Manager. Will not perform "
+ + "query until this is accomplished.", ioe);
+ context.yield();
+ return;
+ }
+ // Make a mutable copy of the current state property map. This
will be updated by the result row callback, and eventually
+ // set as the current state map (after the session has been
committed)
+ final Map<String, String> statePropertyMap = new
HashMap<>(stateMap.toMap());
+
+ final String selectQuery = getQuery(tableName, columnNames,
getColumns(maxValueColumnNames), stateMap, preProcessStrategy);
+ final StopWatch stopWatch = new StopWatch(true);
+
+ try (final Connection con = dbcpService.getConnection();
+ final Statement st = con.createStatement()) {
+
+ final Integer queryTimeout =
context.getProperty(QUERY_TIMEOUT).asTimePeriod(TimeUnit.SECONDS).intValue();
+ st.setQueryTimeout(queryTimeout); // timeout in seconds
+
+ final LongHolder nrOfRows = new LongHolder(0L);
+
+ 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);
+ // Max values will be updated in the state
property map by the callback
+ final MaxValueResultSetRowCollector
maxValCollector = new MaxValueResultSetRowCollector(statePropertyMap,
preProcessStrategy);
+
nrOfRows.set(JdbcCommon.convertToAvroStream(resultSet, out, tableName,
maxValCollector));
+
+ } catch (final SQLException e) {
+ throw new ProcessException("Error during database
query or conversion of records to Avro", e);
+ }
+ }
+ });
+
+ if (nrOfRows.get() > 0) {
+ // 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",
+ stopWatch.getElapsed(TimeUnit.MILLISECONDS));
+ session.transfer(fileToProcess, REL_SUCCESS);
+ } else {
+ // If there were no rows returned, don't send the flowfile
+ session.remove(fileToProcess);
+ context.yield();
+ }
+
+ } catch (final Throwable /*ProcessException | SQLException*/ e) {
--- End diff --
Should avoid catching Throwable, or the general Exception in Processors. If
Exceptions are thrown such as FlowFileAccessException, it is typically best to
let those bubble up to the framework level and be dealt with appropriately
there.
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