docs/UserGuide/API/Programming-Java-Native-API.md

Java Native API

Dependencies

JDK >= 1.8
Maven >= 3.6

Installation

In root directory:

mvn clean install -pl session -am -DskipTests

Using IoTDB Java Native API with Maven

<dependencies>
    <dependency>
      <groupId>org.apache.iotdb</groupId>
      <artifactId>iotdb-session</artifactId>
      <version>0.13.0-SNAPSHOT</version>
    </dependency>
</dependencies>

Native APIs

Here we show the commonly used interfaces and their parameters in the Native API:

Initialize a Session

    // use default configuration 
    session = new Session.Builder.build();

    // initialize with a single node
    session = 
        new Session.Builder()
            .host(String host)
            .port(int port)
            .build();

    // initialize with multiple nodes
    session = 
        new Session.Builder()
            .nodeUrls(List<String> nodeUrls)
            .build();

    // other configurations
    session = 
        new Session.Builder()
            .fetchSize(int fetchSize)
            .username(String username)
            .password(String password)
            .thriftDefaultBufferSize(int thriftDefaultBufferSize)
            .thriftMaxFrameSize(int thriftMaxFrameSize)
            .enableCacheLeader(boolean enableCacheLeader)
            .build();

Open a Session

Session.open()

Close a Session

Session.close()

Set storage group

void setStorageGroup(String storageGroupId)

Delete one or several storage groups

void deleteStorageGroup(String storageGroup)
void deleteStorageGroups(List<String> storageGroups)

Create one or multiple timeseries

void createTimeseries(String path, TSDataType dataType,
      TSEncoding encoding, CompressionType compressor, Map<String, String> props,
      Map<String, String> tags, Map<String, String> attributes, String measurementAlias)
      
void createMultiTimeseries(List<String> paths, List<TSDataType> dataTypes,
      List<TSEncoding> encodings, List<CompressionType> compressors,
      List<Map<String, String>> propsList, List<Map<String, String>> tagsList,
      List<Map<String, String>> attributesList, List<String> measurementAliasList)

Create aligned timeseries

void createAlignedTimeseries(String prefixPath, List<String> measurements,
      List<TSDataType> dataTypes, List<TSEncoding> encodings,
      CompressionType compressor, List<String> measurementAliasList);

Attention: Alias of measurements are not supported currently.

Delete one or several timeseries

void deleteTimeseries(String path)
void deleteTimeseries(List<String> paths)

Delete data before or equal to a timestamp of one or several timeseries

void deleteData(String path, long time)
void deleteData(List<String> paths, long time)

Insert a Record，which contains multiple measurement value of a device at a timestamp. Without type info the server has to do type inference, which may cost some time

void insertRecord(String prefixPath, long time, List<String> measurements, List<String> values)

Insert a Tablet，which is multiple rows of a device, each row has the same measurements

void insertTablet(Tablet tablet)

Insert multiple Tablets

void insertTablets(Map<String, Tablet> tablet)

Insert multiple Records. Without type info the server has to do type inference, which may cost some time

void insertRecords(List<String> deviceIds, List<Long> times, 
                   List<List<String>> measurementsList, List<List<String>> valuesList)

Insert a Record, which contains multiple measurement value of a device at a timestamp. With type info the server has no need to do type inference, which leads a better performance

void insertRecord(String deviceId, long time, List<String> measurements,
   List<TSDataType> types, List<Object> values)

Insert multiple Records. With type info the server has no need to do type inference, which leads a better performance

void insertRecords(List<String> deviceIds, List<Long> times,
    List<List<String>> measurementsList, List<List<TSDataType>> typesList,
    List<List<Object>> valuesList)

Insert multiple Records that belong to the same device. With type info the server has no need to do type inference, which leads a better performance

void insertRecordsOfOneDevice(String deviceId, List<Long> times,
    List<List<String>> measurementsList, List<List<TSDataType>> typesList,
    List<List<Object>> valuesList)

Raw data query. Time interval include startTime and exclude endTime

SessionDataSet executeRawDataQuery(List<String> paths, long startTime, long endTime)

Execute query statement

SessionDataSet executeQueryStatement(String sql)

Execute non query statement

void executeNonQueryStatement(String sql)

Native APIs for profiling network cost

Test the network and client cost of insertRecords. This method NOT insert data into database and server just return after accept the request, this method should be used to test other time cost in client

void testInsertRecords(List<String> deviceIds, List<Long> times,
              List<List<String>> measurementsList, List<List<String>> valuesList)

void testInsertRecords(List<String> deviceIds, List<Long> times,
    List<List<String>> measurementsList, List<List<TSDataType>> typesList,
    List<List<Object>> valuesList)

Test the network and client cost of insertRecordsOfOneDevice. This method NOT insert data into database and server just return after accept the request, this method should be used to test other time cost in client

void testInsertRecordsOfOneDevice(String deviceId, List<Long> times,
    List<List<String>> measurementsList, List<List<TSDataType>> typesList,
    List<List<Object>> valuesList)

Test the network and client cost of insertRecord. This method NOT insert data into database and server just return after accept the request, this method should be used to test other time cost in client

void testInsertRecord(String deviceId, long time, List<String> measurements, List<String> values)

void testInsertRecord(String deviceId, long time, List<String> measurements,
    List<TSDataType> types, List<Object> values)

Test the network and client cost of insertTablet. This method NOT insert data into database and server just return after accept the request, this method should be used to test other time cost in client

void testInsertTablet(Tablet tablet)

Coding Examples

To get more information of the following interfaces, please view session/src/main/java/org/apache/iotdb/session/Session.java

The sample code of using these interfaces is in example/session/src/main/java/org/apache/iotdb/SessionExample.java，which provides an example of how to open an IoTDB session, execute a batch insertion.

Session Pool for Native API

We provide a connection pool (`SessionPool) for Native API. Using the interface, you need to define the pool size.

If you can not get a session connection in 60 seconds, there is a warning log but the program will hang.

If a session has finished an operation, it will be put back to the pool automatically. If a session connection is broken, the session will be removed automatically and the pool will try to create a new session and redo the operation.

For query operations:

When using SessionPool to query data, the result set is SessionDataSetWrapper;
Given a SessionDataSetWrapper, if you have not scanned all the data in it and stop to use it, you have to call SessionPool.closeResultSet(wrapper) manually;
When you call hasNext() and next() of a SessionDataSetWrapper and there is an exception, then you have to call SessionPool.closeResultSet(wrapper) manually;
You can call getColumnNames() of SessionDataSetWrapper to get the column names of query result;

Examples: session/src/test/java/org/apache/iotdb/session/pool/SessionPoolTest.java

Or example/session/src/main/java/org/apache/iotdb/SessionPoolExample.java

For examples of aligned timeseries and measurement template, you can refer to example/session/src/main/java/org/apache/iotdb/AlignedTimeseriesSessionExample.java

New Interfaces

void open(boolean enableRPCCompression)

Open a session, with a parameter to specify whether to enable RPC compression. Please pay attention that this RPC compression status of client must comply with the status of IoTDB server

void insertRecord(String deviceId, long time, List<String> measurements,
      List<TSDataType> types, List<Object> values)

Insert one record, in a way that user has to provide the type information of each measurement, which is different from the original insertRecord() interface. The values should be provided in their primitive types. This interface is more proficient than the one without type parameters.

void insertRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, 
                   List<List<TSDataType>> typesList, List<List<Object>> valuesList)

Insert multiple records with type parameters. This interface is more proficient than the one without type parameters.

void insertTablet(Tablet tablet, boolean sorted)

An additional insertTablet() interface that providing a “sorted” parameter indicating if the tablet is in order. A sorted tablet may accelerate the insertion process.

void insertTablets(Map<String, Tablet> tablets)

A new insertTablets() for inserting multiple tablets.

void insertTablets(Map<String, Tablet> tablets, boolean sorted)

insertTablets() with an additional “sorted” parameter.

void testInsertRecord(String deviceId, long time, List<String> measurements, List<TSDataType> types, 
                      List<Object> values)
void testInsertRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, 
                      List<List<TSDataType>> typesList, List<List<Object>> valuesList)
void testInsertTablet(Tablet tablet, boolean sorted)
void testInsertTablets(Map<String, Tablet> tablets)
void testInsertTablets(Map<String, Tablet> tablets, boolean sorted)

The above interfaces are newly added to test responsiveness of new insert interfaces.

void createTimeseries(String path, TSDataType dataType, TSEncoding encoding, CompressionType compressor, 	
                      Map<String, String> props, Map<String, String> tags, Map<String, String> attributes, 
                      String measurementAlias)

Create a timeseries with path, datatype, encoding and compression. Additionally, users can provide props, tags, attributes and measurementAlias。

void createMultiTimeseries(List<String> paths, List<TSDataType> dataTypes, List<TSEncoding> encodings, 
                           List<CompressionType> compressors, List<Map<String, String>> propsList, 
                           List<Map<String, String>> tagsList, List<Map<String, String>> attributesList, 
                           List<String> measurementAliasList)

Create multiple timeseries with a single method. Users can provide props, tags, attributes and measurementAlias as well for detailed timeseries information.

void createAlignedTimeseries(String devicePath, List<String> measurements,
      List<TSDataType> dataTypes, List<TSEncoding> encodings,
      CompressionType compressor, List<String> measurementAliasList);

Create aligned timeseries with device path, measurements, data types, encodings, compression.

Attention: Alias of measurements are not supported currently.


boolean checkTimeseriesExists(String path)

Add a method to check whether the specific timeseries exists.

public Session(String host, int rpcPort, String username, String password,
      boolean isEnableCacheLeader)

Open a session and specifies whether the Leader cache is enabled. Note that this interface improves performance for distributed IoTDB, but adds less cost to the client for stand-alone IoTDB.

void createSchemaTemplate(Template template)

Create a schema template for massive identical subtree will help to improve memory performance. You can use the API above to create a template at server side, and use Template, InternalNode and MeasurementNode to depict the structure of the template, and use belowed interface to create it inside session.

public void createSchemaTemplate(Template template);

Class Template {
    private String name;
    private boolean directShareTime;
    Map<String, Node> children;
    public Template(String name, boolean isShareTime);
    
    public void addToTemplate(Node node);
    public void deleteFromTemplate(String name);
    public void setShareTime(boolean shareTime);
}

Abstract Class Node {
    private String name;
    public void addChild(Node node);
    public void deleteChild(Node node);
}

Class InternalNode extends Node {
    boolean shareTime;
    Map<String, Node> children;
    public void setShareTime(boolean shareTime);
    public InternalNode(String name, boolean isShareTime);
}

Class MeasurementNode extends Node {
    TSDataType dataType;
    TSEncoding encoding;
    CompressionType compressor;
    public MeasurementNode(String name, 
                           TSDataType dataType, 
                           TSEncoding encoding,
                          CompressionType compressor);
}

A snippet of using above Method and Class：

MeasurementNode nodeX = new MeasurementNode("x", TSDataType.FLOAT, TSEncoding.RLE, CompressionType.SNAPPY);
MeasurementNode nodeY = new MeasurementNode("y", TSDataType.FLOAT, TSEncoding.RLE, CompressionType.SNAPPY);
MeasurementNode nodeSpeed = new MeasurementNode("speed", TSDataType.DOUBLE, TSEncoding.GORILLA, CompressionType.SNAPPY);

InternalNode internalGPS = new InternalNode("GPS", true);
InternalNode internalVehicle = new InternalNode("vehicle", false);

internalGPS.addChild(nodeX);
internalGPS.addChild(nodeY);
internalVehicle.addChild(GPS);
internalVehicle.addChild(nodeSpeed);

Template template = new Template("treeTemplateExample");
template.addToTemplate(internalGPS);
template.addToTemplate(internalVehicle);
template.addToTemplate(nodeSpeed);

createSchemaTemplate(template);

After measurement template created, you can edit the template with belowed APIs.

**Attention: **

1. templates had been set could not be pruned

2. templates will be activated until data points insert into correspoding measurements

3. templates will not be shown by showtimeseries before activating

// Add aligned measurements to a template
public void addAlignedMeasurementsInTemplate(String templateName,
    						  String[] measurementsPath,
                              TSDataType[] dataTypes,
                              TSEncoding[] encodings,
                              CompressionType[] compressors);

// Add one aligned measurement to a template
public void addAlignedMeasurementInTemplate(String templateName,
                                String measurementPath,
                                TSDataType dataType,
                                TSEncoding encoding,
                                CompressionType compressor);


// Add unaligned measurements to a template
public void addUnalignedMeasurementInTemplate(String templateName,
                                String measurementPath,
                                TSDataType dataType,
                                TSEncoding encoding,
                                CompressionType compressor);
                                
// Add one unaligned measurement to a template
public void addUnalignedMeasurementsIntemplate(String templateName,
                                String[] measurementPaths,
                                TSDataType[] dataTypes,
                                TSEncoding[] encodings,
                                CompressionType[] compressors);

// Delete a node in template and its children
public void deleteNodeInTemplate(String templateName, String path);

You can query measurement templates with these APIS:

// Return the amount of measurements inside a template
public int countMeasurementsInTemplate(String templateName);

// Return true if path points to a measurement, otherwise returne false
public boolean isMeasurementInTemplate(String templateName, String path);

// Return true if path exists in template, otherwise return false
public boolean isPathExistInTemplate(String templateName, String path);

// Return all measurements paths inside template
public List<String> showMeasurementsInTemplate(String templateName);

// Return all measurements paths under the designated patter inside template
public List<String> showMeasurementsInTemplate(String templateName, String pattern);

Set the measurement template named ‘templateName’ at path ‘prefixPath’.

void setSchemaTemplate(String templateName, String prefixPath)

Before setting template, you should firstly create the template using

void createSchemaTemplate(Template template)

void unsetSchemaTemplate(String prefixPath, String templateName)

Unset the measurement template named ‘templateName’ from path ‘prefixPath’. You should ensure that there is a template named ‘templateName’ set at the path ‘prefixPath’.

Attention: Unsetting the template named ‘templateName’ from node at path ‘prefixPath’ or descendant nodes which have already inserted records using template is not supported.

Cluster information related APIs (only works in the cluster mode)

Cluster information related APIs allow users get the cluster info like where a storage group will be partitioned to, the status of each node in the cluster.

To use the APIs, add dependency in your pom file:

<dependencies>
    <dependency>
      <groupId>org.apache.iotdb</groupId>
      <artifactId>iotdb-thrift-cluster</artifactId>
      <version>0.13.0-SNAPSHOT</version>
    </dependency>
</dependencies>

How to open a connection:

import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TTransportException;
import org.apache.iotdb.rpc.RpcTransportFactory;

    public class CluserInfoClient {
      TTransport transport;
      ClusterInfoService.Client client;
      public void connect() {
          transport =
              RpcTransportFactory.INSTANCE.getTransport(
                  new TSocket(
                      // the RPC address
                      IoTDBDescriptor.getInstance().getConfig().getRpcAddress(),
                      // the RPC port
                      ClusterDescriptor.getInstance().getConfig().getClusterRpcPort()));
          try {
            transport.open();
          } catch (TTransportException e) {
            Assert.fail(e.getMessage());
          }
          //get the client
          client = new ClusterInfoService.Client(new TBinaryProtocol(transport));
       }
      public void close() {
        transport.close();
      }  
    }

APIs in ClusterInfoService.Client:

Get the physical hash ring of the cluster:

list<Node> getRing();

Get data partition information of input path and time range:

    /**
     * @param path input path (should contains a Storage group name as its prefix)
     * @return the data partition info. If the time range only covers one data partition, the the size
     * of the list is one.
     */
    list<DataPartitionEntry> getDataPartition(1:string path, 2:long startTime, 3:long endTime);

Get metadata partition information of input path:

    /**
     * @param path input path (should contains a Storage group name as its prefix)
     * @return metadata partition information
     */
    list<Node> getMetaPartition(1:string path);

Get the status (alive or not) of all nodes:

    /**
     * @return key: node, value: live or not
     */
    map<Node, bool> getAllNodeStatus();

get the raft group info (voteFor, term, etc..) of the connected node (Notice that this API is rarely used by users):

    /**
     * @return A multi-line string with each line representing the total time consumption, invocation
     *     number, and average time consumption.
     */
    string getInstrumentingInfo();