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<a href="/docs/2.15.0/quick-start/dotnet"
class=''
>.NET/C#</a>
</li>
<li>
<a href="/docs/2.15.0/quick-start/cpp"
class=''
>C++</a>
</li>
<li>
<a href="/docs/2.15.0/quick-start/python"
class=''
>Python</a>
</li>
<li>
<a href="/docs/2.15.0/quick-start/nodejs"
class=''
>Node.JS</a>
</li>
<li>
<a href="/docs/2.15.0/quick-start/sql"
class=''
>SQL</a>
</li>
<li>
<a href="/docs/2.15.0/quick-start/php"
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>PHP</a>
</li>
<li>
<a href="/docs/2.15.0/quick-start/restapi"
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>REST API</a>
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<button type='button' class='group-toggle collapsed '>Installation<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<a href="/docs/2.15.0/installation/installing-using-zip"
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>Installing Using ZIP Archive</a>
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<li>
<a href="/docs/2.15.0/installation/installing-using-docker"
class=''
>Installing Using Docker</a>
</li>
<li>
<a href="/docs/2.15.0/installation/deb-rpm"
class=''
>Installing DEB or RPM package</a>
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<li>
<button
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<li><a href="/docs/2.15.0/installation/kubernetes/amazon-eks-deployment" class=''>Amazon EKS</a></li>
<li><a href="/docs/2.15.0/installation/kubernetes/azure-deployment" class=''>Azure Kubernetes Service</a></li>
<li><a href="/docs/2.15.0/installation/kubernetes/gke-deployment" class=''>Google Kubernetes Engine</a></li>
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</li>
<li>
<a href="/docs/2.15.0/installation/vmware-installation"
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>VMWare</a>
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<li>
<button type='button' class='group-toggle collapsed '>Setting Up<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/understanding-configuration"
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>Understanding Configuration</a>
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<li>
<a href="/docs/2.15.0/setup"
class=''
>Setting Up</a>
</li>
<li>
<a href="/docs/2.15.0/logging"
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>Configuring Logging</a>
</li>
<li>
<a href="/docs/2.15.0/resources-injection"
class=''
>Resources Injection</a>
</li>
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</li>
<li>
<a href="/docs/2.15.0/starting-nodes" class='' >Starting and Stopping Nodes</a>
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<li>
<button type='button' class='group-toggle collapsed '>Clustering<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/clustering/clustering"
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>Overview</a>
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<li>
<a href="/docs/2.15.0/clustering/tcp-ip-discovery"
class=''
>TCP/IP Discovery</a>
</li>
<li>
<a href="/docs/2.15.0/clustering/zookeeper-discovery"
class=''
>ZooKeeper Discovery</a>
</li>
<li>
<a href="/docs/2.15.0/clustering/discovery-in-the-cloud"
class=''
>Discovery in the Cloud</a>
</li>
<li>
<a href="/docs/2.15.0/clustering/network-configuration"
class=''
>Network Configuration</a>
</li>
<li>
<a href="/docs/2.15.0/clustering/connect-client-nodes"
class=''
>Connecting Client Nodes</a>
</li>
<li>
<a href="/docs/2.15.0/clustering/baseline-topology"
class=''
>Baseline Topology</a>
</li>
<li>
<a href="/docs/2.15.0/clustering/running-client-nodes-behind-nat"
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>Running Client Nodes Behind NAT</a>
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</li>
<li>
<button type='button' class='group-toggle collapsed '>Thin Clients<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/thin-clients/getting-started-with-thin-clients"
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>Thin Clients Overview</a>
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<li>
<a href="/docs/2.15.0/thin-clients/java-thin-client"
class=''
>Java Thin Client</a>
</li>
<li>
<a href="/docs/2.15.0/thin-clients/dotnet-thin-client"
class=''
>.NET Thin Client</a>
</li>
<li>
<a href="/docs/2.15.0/thin-clients/cpp-thin-client"
class=''
>C++ Thin Client</a>
</li>
<li>
<a href="/docs/2.15.0/thin-clients/python-thin-client"
class=''
>Python Thin Client</a>
</li>
<li>
<a href="/docs/2.15.0/thin-clients/php-thin-client"
class=''
>PHP Thin Client</a>
</li>
<li>
<a href="/docs/2.15.0/thin-clients/nodejs-thin-client"
class=''
>Node.js Thin Client</a>
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<li>
<button
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<li><a href="/docs/2.15.0/binary-client-protocol/binary-client-protocol" class=''>Binary Client Protocol</a></li>
<li><a href="/docs/2.15.0/binary-client-protocol/data-format" class=''>Data Format</a></li>
<li><a href="/docs/2.15.0/binary-client-protocol/key-value-queries" class=''>Key-Value Queries</a></li>
<li><a href="/docs/2.15.0/binary-client-protocol/sql-and-scan-queries" class=''>SQL and Scan Queries</a></li>
<li><a href="/docs/2.15.0/binary-client-protocol/binary-type-metadata" class=''>Binary Types Metadata</a></li>
<li><a href="/docs/2.15.0/binary-client-protocol/cache-configuration" class=''>Cache Configuration</a></li>
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</li>
</nav>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Data Modeling<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/data-modeling/data-modeling"
class=''
>Introduction</a>
</li>
<li>
<a href="/docs/2.15.0/data-modeling/data-partitioning"
class=''
>Data Partitioning</a>
</li>
<li>
<a href="/docs/2.15.0/data-modeling/affinity-collocation"
class=''
>Affinity Colocation</a>
</li>
<li>
<a href="/docs/2.15.0/data-modeling/binary-marshaller"
class=''
>Binary Marshaller</a>
</li>
</nav>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Configuring Memory<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class='nav-group collapsed'>
<li>
<a href="/docs/2.15.0/memory-architecture"
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>Memory Architecture</a>
</li>
<li>
<a href="/docs/2.15.0/memory-configuration/data-regions"
class=''
>Configuring Data Regions</a>
</li>
<li>
<a href="/docs/2.15.0/memory-configuration/eviction-policies"
class=''
>Eviction Policies</a>
</li>
<li>
<a href="/docs/2.15.0/memory-configuration/replacement-policies"
class=''
>Replacement Policies</a>
</li>
</nav>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Configuring Persistence<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class='nav-group collapsed'>
<li>
<a href="/docs/2.15.0/persistence/native-persistence"
class=''
>Ignite Persistence</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/external-storage"
class=''
>External Storage</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/swap"
class=''
>Swapping</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/custom-cache-store"
class=''
>Implementing Custom Cache Store</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/snapshot-directory"
class=''
>Configuring Snapshot Directory</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/disk-compression"
class=''
>Disk Compression</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/persistence-tuning"
class=''
>Tuning Persistence</a>
</li>
<li>
<a href="/docs/2.15.0/persistence/change-data-capture"
class=''
>Change Data Capture</a>
</li>
</nav>
</li>
<li>
<a href="/docs/2.15.0/snapshots/snapshots" class='' >Cluster Snapshots</a>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Configuring Caches<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class='nav-group collapsed'>
<li>
<a href="/docs/2.15.0/configuring-caches/configuration-overview"
class=''
>Cache Configuration</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/configuring-backups"
class=''
>Configuring Partition Backups</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/partition-loss-policy"
class=''
>Partition Loss Policy</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/atomicity-modes"
class=''
>Atomicity Modes</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/expiry-policies"
class=''
>Expiry Policy</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/on-heap-caching"
class=''
>On-Heap Caching</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/cache-groups"
class=''
>Cache Groups</a>
</li>
<li>
<a href="/docs/2.15.0/configuring-caches/near-cache"
class=''
>Near Caches</a>
</li>
</nav>
</li>
<li>
<a href="/docs/2.15.0/data-rebalancing" class='' >Data Rebalancing</a>
</li>
<li>
<a href="/docs/2.15.0/data-streaming" class='active' >Data Streaming</a>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Using Key-Value API<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class='nav-group collapsed'>
<li>
<a href="/docs/2.15.0/key-value-api/basic-cache-operations"
class=''
>Basic Cache Operations</a>
</li>
<li>
<a href="/docs/2.15.0/key-value-api/binary-objects"
class=''
>Working with Binary Objects</a>
</li>
<li>
<a href="/docs/2.15.0/key-value-api/using-cache-queries"
class=''
>Using Cache Queries</a>
</li>
<li>
<a href="/docs/2.15.0/key-value-api/read-repair"
class=''
>Read Repair</a>
</li>
</nav>
</li>
<li>
<a href="/docs/2.15.0/key-value-api/transactions" class='' >Performing Transactions</a>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Working with SQL<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class='nav-group collapsed'>
<li>
<a href="/docs/2.15.0/SQL/sql-introduction"
class=''
>Introduction</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/schemas"
class=''
>Understanding Schemas</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/indexes"
class=''
>Defining Indexes</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/sql-api"
class=''
>Using SQL API</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/distributed-joins"
class=''
>Distributed Joins</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/custom-sql-func"
class=''
>Custom SQL Functions</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/JDBC/jdbc-driver"
class=''
>JDBC Driver</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/JDBC/jdbc-client-driver"
class=''
>JDBC Client Driver</a>
</li>
<li>
<button
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class='collapsed '>ODBC Driver<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class="sub_pages collapsed">
<li><a href="/docs/2.15.0/SQL/ODBC/odbc-driver" class=''>ODBC Driver</a></li>
<li><a href="/docs/2.15.0//SQL/ODBC/connection-string-dsn" class=''>Connection String and DSN</a></li>
<li><a href="/docs/2.15.0/SQL/ODBC/querying-modifying-data" class=''>Querying and Modifying Data</a></li>
<li><a href="/docs/2.15.0/SQL/ODBC/specification" class=''>Specification</a></li>
<li><a href="/docs/2.15.0/SQL/ODBC/data-types" class=''>Data Types</a></li>
<li><a href="/docs/2.15.0/SQL/ODBC/error-codes" class=''>Error Codes</a></li>
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</li>
<li>
<a href="/docs/2.15.0/transactions/mvcc"
class=''
>Multiversion Concurrency Control</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/sql-statistics"
class=''
>SQL Statistics</a>
</li>
<li>
<a href="/docs/2.15.0/SQL/sql-calcite"
class=''
>Calcite-based SQL Engine</a>
</li>
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</li>
<li>
<button type='button' class='group-toggle collapsed '>SQL Reference<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/sql-reference/sql-conformance"
class=''
>SQL Conformance</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/ddl"
class=''
>Data Definition Language (DDL)</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/dml"
class=''
>Data Manipulation Language (DML)</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/transactions"
class=''
>Transactions</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/operational-commands"
class=''
>Operational Commands</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/aggregate-functions"
class=''
>Aggregate functions</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/numeric-functions"
class=''
>Numeric Functions</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/string-functions"
class=''
>String Functions</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/date-time-functions"
class=''
>Data and Time Functions</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/system-functions"
class=''
>System Functions</a>
</li>
<li>
<a href="/docs/2.15.0/sql-reference/data-types"
class=''
>Data Types</a>
</li>
</nav>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Distributed Computing<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/distributed-computing/distributed-computing"
class=''
>Distributed Computing API</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/cluster-groups"
class=''
>Cluster Groups</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/executor-service"
class=''
>Executor Service</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/map-reduce"
class=''
>MapReduce API</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/load-balancing"
class=''
>Load Balancing</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/fault-tolerance"
class=''
>Fault Tolerance</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/job-scheduling"
class=''
>Job Scheduling</a>
</li>
<li>
<a href="/docs/2.15.0/distributed-computing/collocated-computations"
class=''
>Colocating Computations with Data</a>
</li>
</nav>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Code Deployment<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/code-deployment/deploying-user-code"
class=''
>Deploying User Code</a>
</li>
<li>
<a href="/docs/2.15.0/code-deployment/peer-class-loading"
class=''
>Peer Class Loading</a>
</li>
</nav>
</li>
<li>
<button type='button' class='group-toggle collapsed '>Machine Learning<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li>
<a href="/docs/2.15.0/machine-learning/machine-learning"
class=''
>Machine Learning</a>
</li>
<li>
<a href="/docs/2.15.0/machine-learning/partition-based-dataset"
class=''
>Partition Based Dataset</a>
</li>
<li>
<a href="/docs/2.15.0/machine-learning/updating-trained-models"
class=''
>Updating Trained Models</a>
</li>
<li>
<button
type='button'
class='collapsed '>Binary Classification<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class="sub_pages collapsed">
<li><a href="/docs/2.15.0/machine-learning/binary-classification/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/linear-svm" class=''>Linear SVM (Support Vector Machine)</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/decision-trees" class=''>Decision Trees</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/multilayer-perceptron" class=''>Multilayer Perceptron</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/logistic-regression" class=''>Logistic Regression</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/knn-classification" class=''>k-NN Classification</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/ann" class=''>ANN (Approximate Nearest Neighbor)</a></li>
<li><a href="/docs/2.15.0/machine-learning/binary-classification/naive-bayes" class=''>Naive Bayes</a></li>
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</li>
<li>
<button
type='button'
class='collapsed '>Regression<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class="sub_pages collapsed">
<li><a href="/docs/2.15.0/machine-learning/regression/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.15.0/machine-learning/regression/linear-regression" class=''>Linear Regression</a></li>
<li><a href="/docs/2.15.0/machine-learning/regression/decision-trees-regression" class=''>Decision Trees Regression</a></li>
<li><a href="/docs/2.15.0/machine-learning/regression/knn-regression" class=''>k-NN Regression</a></li>
</nav>
</li>
<li>
<button
type='button'
class='collapsed '>Clustering<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class="sub_pages collapsed">
<li><a href="/docs/2.15.0/machine-learning/clustering/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.15.0/machine-learning/clustering/k-means-clustering" class=''>K-Means Clustering</a></li>
<li><a href="/docs/2.15.0/machine-learning/clustering/gaussian-mixture" class=''>Gaussian mixture (GMM)</a></li>
</nav>
</li>
<li>
<a href="/docs/2.15.0/machine-learning/preprocessing"
class=''
>Preprocessing</a>
</li>
<li>
<button
type='button'
class='collapsed '>Model Selection<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class="sub_pages collapsed">
<li><a href="/docs/2.15.0/machine-learning/model-selection/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.15.0/machine-learning/model-selection/evaluator" class=''>Evaluator</a></li>
<li><a href="/docs/2.15.0/machine-learning/model-selection/split-the-dataset-on-test-and-train-datasets" class=''>Split the dataset on test and train datasets</a></li>
<li><a href="/docs/2.15.0/machine-learning/model-selection/hyper-parameter-tuning" class=''>Hyper-parameter tuning</a></li>
<li><a href="/docs/2.15.0/machine-learning/model-selection/pipeline-api" class=''>Pipeline API</a></li>
</nav>
</li>
<li>
<a href="/docs/2.15.0/machine-learning/multiclass-classification"
class=''
>Multiclass Classification</a>
</li>
<li>
<button
type='button'
class='collapsed '>Ensemble Methods<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
<nav class="sub_pages collapsed">
<li><a href="/docs/2.15.0/machine-learning/ensemble-methods/introduction" class=''></a></li>
<li><a href="/docs/2.15.0/machine-learning/ensemble-methods/stacking" class=''>Stacking</a></li>
<li><a href="/docs/2.15.0/machine-learning/ensemble-methods/baggin" class=''>Bagging</a></li>
<li><a href="/docs/2.15.0/machine-learning/ensemble-methods/random-forest" class=''>Random Forest</a></li>
<li><a href="/docs/2.15.0/machine-learning/ensemble-methods/gradient-boosting" class=''>Gradient Boosting</a></li>
</nav>
</li>
<li>
<a href="/docs/2.15.0/machine-learning/recommendation-systems"
class=''
>Recommendation Systems</a>
</li>
<li>
<button
type='button'
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<article data-swiftype-index='true'>
<a class='edit-link' href="https://github.com/apache/ignite/tree/IGNITE-7595/docs/_docs/data-streaming.adoc" target="_blank">Edit</a>
<h1>Data Streaming</h1>
<div class="sect1">
<h2 id="overview">Overview</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Ignite provides a Data Streaming API that can be used to inject large amounts of data into an Ignite cluster.
The main goal of streaming is efficient, quick data loading. The data that is added to the streamer is
automatically organized and distributed between the nodes in partition-aware and parallel manner.</p>
</div>
<div class="paragraph">
<p><span class="image"><img src="/docs/2.15.0/images/data_streaming.png" alt="Data Streaming"></span></p>
</div>
<div class="paragraph">
<p>The Data Streaming API is designed to be scalable and provides <em>at-least-once</em> delivery semantics
for the data streamed into Ignite, meaning each entry is processed at least once.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="usage">Usage</h2>
<div class="sectionbody">
<div class="paragraph">
<p>A data streamer is associated with a specific cache and provides an interface for streaming data into the cache.</p>
</div>
<div class="paragraph">
<p>In a typical scenario, you obtain a data streamer and use one of its methods to stream data into the cache, and Ignite takes care of the rest.</p>
</div>
<div class="paragraph">
<p>You can obtain the data streamer for a specific cache as follows:</p>
</div>
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="c1">// Get the data streamer reference and stream data.</span>
<span class="k">try</span> <span class="o">(</span><span class="nc">IgniteDataStreamer</span><span class="o">&lt;</span><span class="nc">Integer</span><span class="o">,</span> <span class="nc">String</span><span class="o">&gt;</span> <span class="n">stmr</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">dataStreamer</span><span class="o">(</span><span class="s">"myCache"</span><span class="o">))</span> <span class="o">{</span>
<span class="c1">// Stream entries.</span>
<span class="k">for</span> <span class="o">(</span><span class="kt">int</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="o">;</span> <span class="n">i</span> <span class="o">&lt;</span> <span class="mi">100000</span><span class="o">;</span> <span class="n">i</span><span class="o">++)</span>
<span class="n">stmr</span><span class="o">.</span><span class="na">addData</span><span class="o">(</span><span class="n">i</span><span class="o">,</span> <span class="nc">Integer</span><span class="o">.</span><span class="na">toString</span><span class="o">(</span><span class="n">i</span><span class="o">));</span>
<span class="o">}</span>
<span class="nc">System</span><span class="o">.</span><span class="na">out</span><span class="o">.</span><span class="na">println</span><span class="o">(</span><span class="s">"dataStreamerExample output:"</span> <span class="o">+</span> <span class="n">cache</span><span class="o">.</span><span class="na">get</span><span class="o">(</span><span class="mi">99999</span><span class="o">));</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>In the Java version of Ignite, a data streamer is an implementation of the <code>IgniteDataStreamer</code> interface. <code>IgniteDataStreamer</code> provides a number of <code>addData(&#8230;&#8203;)</code> methods for adding key-value pairs to caches. Refer to the <a href="https://ignite.apache.org/releases/2.15.0/javadoc/org/apache/ignite/IgniteDataStreamer.html">IgniteDataStreamer</a> javadoc for the complete list of methods.</p>
</div></code-tab><code-tab data-tab='C#/.NET'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="csharp"><span class="k">using</span> <span class="p">(</span><span class="kt">var</span> <span class="n">stmr</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetDataStreamer</span><span class="p">&lt;</span><span class="kt">int</span><span class="p">,</span> <span class="kt">string</span><span class="p">&gt;(</span><span class="s">"myCache"</span><span class="p">))</span>
<span class="p">{</span>
<span class="k">for</span> <span class="p">(</span><span class="kt">var</span> <span class="n">i</span> <span class="p">=</span> <span class="m">0</span><span class="p">;</span> <span class="n">i</span> <span class="p">&lt;</span> <span class="m">1000</span><span class="p">;</span> <span class="n">i</span><span class="p">++)</span>
<span class="n">stmr</span><span class="p">.</span><span class="nf">AddData</span><span class="p">(</span><span class="n">i</span><span class="p">,</span> <span class="n">i</span><span class="p">.</span><span class="nf">ToString</span><span class="p">());</span>
<span class="p">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C++' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C++.</code></pre>
</div>
</div></code-tab></code-tabs>
<div class="paragraph">
<p>The streamer can accept data to load by multiple threads.</p>
</div>
<div class="paragraph">
<p>A good use of streaming is data preloading.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="limitations">Limitations</h2>
<div class="sectionbody">
<div class="paragraph">
<p>DataStreamer doesn&#8217;t guarantee:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>By default, data consistency until successfully finished;</p>
</li>
<li>
<p>Immediate data loading. Data can be kept for a while before loading;</p>
</li>
<li>
<p>Data order. Data records may be loaded into a cache in a different order compared to load into the streamer;</p>
</li>
<li>
<p>By default, working with external storages.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>If <a href="#overwritting">'allowOverwrite'</a> property is 'false' (default), consider:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>You should not have the same keys repeating in the data being streamed;</p>
</li>
<li>
<p>Streamer cancelation or streamer node failure can cause data inconsistency;</p>
</li>
<li>
<p>If loading into a persistent cache, concurrently created snapshot may contain inconsistent data and might not be restored entirely.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>Most important behavior of Ignite Data Streamer is defined by <a href="#receivers">stream receiver</a> and
<a href="#overwritting">'allowOverwite' setting.</a></p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="receivers">Streamer receivers.</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Ignite DataStreamer is an orchestrator and doesn&#8217;t write data itself. <a href="https://ignite.apache.org/releases/2.15.0/javadoc/org/apache/ignite/stream/StreameReceiver.html">StreamerReceiver</a> does. The default receiver is designed for fastest load and fewer network requests. With this receiver, streamer focuses on parallel transfer of backup and primary records.</p>
</div>
<div class="paragraph">
<p>You can set your own receiver. See <a href="#transfomer">Stream Transformer</a> and <a href="#visitor">Stream Visitor</a>. The logic implemented in a stream receiver is executed on the node where data is to be stored.</p>
</div>
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="k">try</span> <span class="o">(</span><span class="nc">IgniteDataStreamer</span><span class="o">&lt;</span><span class="nc">Integer</span><span class="o">,</span> <span class="nc">String</span><span class="o">&gt;</span> <span class="n">stmr</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">dataStreamer</span><span class="o">(</span><span class="s">"myCache"</span><span class="o">))</span> <span class="o">{</span>
<span class="n">stmr</span><span class="o">.</span><span class="na">allowOverwrite</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span>
<span class="n">stmr</span><span class="o">.</span><span class="na">receiver</span><span class="o">((</span><span class="nc">StreamReceiver</span><span class="o">&lt;</span><span class="nc">Integer</span><span class="o">,</span> <span class="nc">String</span><span class="o">&gt;)</span> <span class="o">(</span><span class="n">cache</span><span class="o">,</span> <span class="n">entries</span><span class="o">)</span> <span class="o">-&gt;</span> <span class="n">entries</span><span class="o">.</span><span class="na">forEach</span><span class="o">(</span><span class="n">entry</span> <span class="o">-&gt;</span> <span class="o">{</span>
<span class="c1">// do something with the entry</span>
<span class="n">cache</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">entry</span><span class="o">.</span><span class="na">getKey</span><span class="o">(),</span> <span class="n">entry</span><span class="o">.</span><span class="na">getValue</span><span class="o">());</span>
<span class="o">}));</span>
<span class="o">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C#/.NET'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="csharp"><span class="k">private</span> <span class="k">class</span> <span class="nc">MyStreamReceiver</span> <span class="p">:</span> <span class="n">IStreamReceiver</span><span class="p">&lt;</span><span class="kt">int</span><span class="p">,</span> <span class="kt">string</span><span class="p">&gt;</span>
<span class="p">{</span>
<span class="k">public</span> <span class="k">void</span> <span class="nf">Receive</span><span class="p">(</span><span class="n">ICache</span><span class="p">&lt;</span><span class="kt">int</span><span class="p">,</span> <span class="kt">string</span><span class="p">&gt;</span> <span class="n">cache</span><span class="p">,</span> <span class="n">ICollection</span><span class="p">&lt;</span><span class="n">ICacheEntry</span><span class="p">&lt;</span><span class="kt">int</span><span class="p">,</span> <span class="kt">string</span><span class="p">&gt;&gt;</span> <span class="n">entries</span><span class="p">)</span>
<span class="p">{</span>
<span class="k">foreach</span> <span class="p">(</span><span class="kt">var</span> <span class="n">entry</span> <span class="k">in</span> <span class="n">entries</span><span class="p">)</span>
<span class="p">{</span>
<span class="c1">// do something with the entry</span>
<span class="n">cache</span><span class="p">.</span><span class="nf">Put</span><span class="p">(</span><span class="n">entry</span><span class="p">.</span><span class="n">Key</span><span class="p">,</span> <span class="n">entry</span><span class="p">.</span><span class="n">Value</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">public</span> <span class="k">static</span> <span class="k">void</span> <span class="nf">StreamReceiverDemo</span><span class="p">()</span>
<span class="p">{</span>
<span class="kt">var</span> <span class="n">ignite</span> <span class="p">=</span> <span class="n">Ignition</span><span class="p">.</span><span class="nf">Start</span><span class="p">();</span>
<span class="k">using</span> <span class="p">(</span><span class="kt">var</span> <span class="n">stmr</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetDataStreamer</span><span class="p">&lt;</span><span class="kt">int</span><span class="p">,</span> <span class="kt">string</span><span class="p">&gt;(</span><span class="s">"myCache"</span><span class="p">))</span>
<span class="p">{</span>
<span class="n">stmr</span><span class="p">.</span><span class="n">AllowOverwrite</span> <span class="p">=</span> <span class="k">true</span><span class="p">;</span>
<span class="n">stmr</span><span class="p">.</span><span class="n">Receiver</span> <span class="p">=</span> <span class="k">new</span> <span class="nf">MyStreamReceiver</span><span class="p">();</span>
<span class="p">}</span>
<span class="p">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C++' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C++.</code></pre>
</div>
</div></code-tab></code-tabs>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<div class="title">Important</div>
</td>
<td class="content">
<div class="paragraph">
<p>The class definitions of the stream receivers to be executed on remote nodes must be available on the nodes. This can be achieved in two ways:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Add the classes to the classpath of the nodes;</p>
</li>
<li>
<p>Enable <a href="/docs/2.15.0/code-deployment/peer-class-loading">peer class loading</a>.</p>
</li>
</ul>
</div>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Changing receiver to non-default changes data distribution algorithm. With non-default receiver streamer sends data batches only to primary node receiver. And primary node needs another requests to send backup writes.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
A stream receiver does not put data into cache automatically. You need to call one of the <code>put</code> methods explicitly.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="overwritting">Overwritting data.</h2>
<div class="sectionbody">
<div class="paragraph">
<p>By default, existing keys aren&#8217;t overwritten. You can change that behavior by setting the <code>allowOverwrite</code> property of the data streamer to <code>true</code>. Since the default receiver does not overwrite data, other provided one is automatically chosen. Any non-default receiver is considered as not-overwriting. And <code>allowOverwrite</code> property says <code>true</code>. However, your own receiver may use <code>putIfAbsent</code> for instance.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
When <code>allowOverwrite</code> is set to <code>false</code> (default), the updates are not propagated to the <a href="/docs/2.15.0/persistence/external-storage">external storage</a> (if it is used).
</td>
</tr>
</table>
</div>
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="n">stmr</span><span class="o">.</span><span class="na">allowOverwrite</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C#/.NET'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="csharp"><span class="n">stmr</span><span class="p">.</span><span class="n">AllowOverwrite</span> <span class="p">=</span> <span class="k">true</span><span class="p">;</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C++' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C++.</code></pre>
</div>
</div></code-tab></code-tabs>
<div class="sect2">
<h3 id="transfomer">Stream Transformer</h3>
<div class="paragraph">
<p>A stream transformer is a convenient implementation of a stream receiver, that updates the data in the stream.
Stream transformers take advantage of the colocation feature and update the data on the node where it is going to be stored.</p>
</div>
<div class="paragraph">
<p>In the example below, we use a stream transformer to increment a counter for each distinct word found in the text stream.</p>
</div>
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="nc">String</span><span class="o">[]</span> <span class="n">text</span> <span class="o">=</span> <span class="o">{</span> <span class="s">"hello"</span><span class="o">,</span> <span class="s">"world"</span><span class="o">,</span> <span class="s">"hello"</span><span class="o">,</span> <span class="s">"Ignite"</span> <span class="o">};</span>
<span class="nc">CacheConfiguration</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Long</span><span class="o">&gt;</span> <span class="n">cfg</span> <span class="o">=</span> <span class="k">new</span> <span class="nc">CacheConfiguration</span><span class="o">&lt;&gt;(</span><span class="s">"wordCountCache"</span><span class="o">);</span>
<span class="nc">IgniteCache</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Long</span><span class="o">&gt;</span> <span class="n">stmCache</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">getOrCreateCache</span><span class="o">(</span><span class="n">cfg</span><span class="o">);</span>
<span class="k">try</span> <span class="o">(</span><span class="nc">IgniteDataStreamer</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Long</span><span class="o">&gt;</span> <span class="n">stmr</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">dataStreamer</span><span class="o">(</span><span class="n">stmCache</span><span class="o">.</span><span class="na">getName</span><span class="o">()))</span> <span class="o">{</span>
<span class="c1">// Allow data updates.</span>
<span class="n">stmr</span><span class="o">.</span><span class="na">allowOverwrite</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span>
<span class="c1">// Configure data transformation to count instances of the same word.</span>
<span class="n">stmr</span><span class="o">.</span><span class="na">receiver</span><span class="o">(</span><span class="nc">StreamTransformer</span><span class="o">.</span><span class="na">from</span><span class="o">((</span><span class="n">e</span><span class="o">,</span> <span class="n">arg</span><span class="o">)</span> <span class="o">-&gt;</span> <span class="o">{</span>
<span class="c1">// Get current count.</span>
<span class="nc">Long</span> <span class="n">val</span> <span class="o">=</span> <span class="n">e</span><span class="o">.</span><span class="na">getValue</span><span class="o">();</span>
<span class="c1">// Increment count by 1.</span>
<span class="n">e</span><span class="o">.</span><span class="na">setValue</span><span class="o">(</span><span class="n">val</span> <span class="o">==</span> <span class="kc">null</span> <span class="o">?</span> <span class="mi">1L</span> <span class="o">:</span> <span class="n">val</span> <span class="o">+</span> <span class="mi">1</span><span class="o">);</span>
<span class="k">return</span> <span class="kc">null</span><span class="o">;</span>
<span class="o">}));</span>
<span class="c1">// Stream words into the streamer cache.</span>
<span class="k">for</span> <span class="o">(</span><span class="nc">String</span> <span class="n">word</span> <span class="o">:</span> <span class="n">text</span><span class="o">)</span>
<span class="n">stmr</span><span class="o">.</span><span class="na">addData</span><span class="o">(</span><span class="n">word</span><span class="o">,</span> <span class="mi">1L</span><span class="o">);</span>
<span class="o">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C#/.NET'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="csharp"><span class="k">class</span> <span class="nc">MyEntryProcessor</span> <span class="p">:</span> <span class="n">ICacheEntryProcessor</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">long</span><span class="p">,</span> <span class="kt">object</span><span class="p">,</span> <span class="kt">object</span><span class="p">&gt;</span>
<span class="p">{</span>
<span class="k">public</span> <span class="kt">object</span> <span class="nf">Process</span><span class="p">(</span><span class="n">IMutableCacheEntry</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">long</span><span class="p">&gt;</span> <span class="n">e</span><span class="p">,</span> <span class="kt">object</span> <span class="n">arg</span><span class="p">)</span>
<span class="p">{</span>
<span class="c1">//get current count</span>
<span class="kt">var</span> <span class="n">val</span> <span class="p">=</span> <span class="n">e</span><span class="p">.</span><span class="n">Value</span><span class="p">;</span>
<span class="c1">//increment count by 1</span>
<span class="n">e</span><span class="p">.</span><span class="n">Value</span> <span class="p">=</span> <span class="n">val</span> <span class="p">==</span> <span class="m">0</span> <span class="p">?</span> <span class="m">1L</span> <span class="p">:</span> <span class="n">val</span> <span class="p">+</span> <span class="m">1</span><span class="p">;</span>
<span class="k">return</span> <span class="k">null</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">public</span> <span class="k">static</span> <span class="k">void</span> <span class="nf">StreamTransformerDemo</span><span class="p">()</span>
<span class="p">{</span>
<span class="kt">var</span> <span class="n">ignite</span> <span class="p">=</span> <span class="n">Ignition</span><span class="p">.</span><span class="nf">Start</span><span class="p">(</span><span class="k">new</span> <span class="n">IgniteConfiguration</span>
<span class="p">{</span>
<span class="n">DiscoverySpi</span> <span class="p">=</span> <span class="k">new</span> <span class="n">TcpDiscoverySpi</span>
<span class="p">{</span>
<span class="n">LocalPort</span> <span class="p">=</span> <span class="m">48500</span><span class="p">,</span>
<span class="n">LocalPortRange</span> <span class="p">=</span> <span class="m">20</span><span class="p">,</span>
<span class="n">IpFinder</span> <span class="p">=</span> <span class="k">new</span> <span class="n">TcpDiscoveryStaticIpFinder</span>
<span class="p">{</span>
<span class="n">Endpoints</span> <span class="p">=</span> <span class="k">new</span><span class="p">[]</span>
<span class="p">{</span>
<span class="s">"127.0.0.1:48500..48520"</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="kt">var</span> <span class="n">cfg</span> <span class="p">=</span> <span class="k">new</span> <span class="nf">CacheConfiguration</span><span class="p">(</span><span class="s">"wordCountCache"</span><span class="p">);</span>
<span class="kt">var</span> <span class="n">stmCache</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetOrCreateCache</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">long</span><span class="p">&gt;(</span><span class="n">cfg</span><span class="p">);</span>
<span class="k">using</span> <span class="p">(</span><span class="kt">var</span> <span class="n">stmr</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetDataStreamer</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">long</span><span class="p">&gt;(</span><span class="n">stmCache</span><span class="p">.</span><span class="n">Name</span><span class="p">))</span>
<span class="p">{</span>
<span class="c1">//Allow data updates</span>
<span class="n">stmr</span><span class="p">.</span><span class="n">AllowOverwrite</span> <span class="p">=</span> <span class="k">true</span><span class="p">;</span>
<span class="c1">//Configure data transformation to count instances of the same word</span>
<span class="n">stmr</span><span class="p">.</span><span class="n">Receiver</span> <span class="p">=</span> <span class="k">new</span> <span class="n">StreamTransformer</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">long</span><span class="p">,</span> <span class="kt">object</span><span class="p">,</span> <span class="kt">object</span><span class="p">&gt;(</span><span class="k">new</span> <span class="nf">MyEntryProcessor</span><span class="p">());</span>
<span class="c1">//stream words into the streamer cache</span>
<span class="k">foreach</span> <span class="p">(</span><span class="kt">var</span> <span class="n">word</span> <span class="k">in</span> <span class="nf">GetWords</span><span class="p">())</span>
<span class="p">{</span>
<span class="n">stmr</span><span class="p">.</span><span class="nf">AddData</span><span class="p">(</span><span class="n">word</span><span class="p">,</span> <span class="m">1L</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="n">Console</span><span class="p">.</span><span class="nf">WriteLine</span><span class="p">(</span><span class="n">stmCache</span><span class="p">.</span><span class="nf">Get</span><span class="p">(</span><span class="s">"a"</span><span class="p">));</span>
<span class="n">Console</span><span class="p">.</span><span class="nf">WriteLine</span><span class="p">(</span><span class="n">stmCache</span><span class="p">.</span><span class="nf">Get</span><span class="p">(</span><span class="s">"b"</span><span class="p">));</span>
<span class="p">}</span>
<span class="k">static</span> <span class="n">IEnumerable</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">&gt;</span> <span class="nf">GetWords</span><span class="p">()</span>
<span class="p">{</span>
<span class="c1">//populate words list somehow</span>
<span class="k">return</span> <span class="n">Enumerable</span><span class="p">.</span><span class="nf">Repeat</span><span class="p">(</span><span class="s">"a"</span><span class="p">,</span> <span class="m">3</span><span class="p">).</span><span class="nf">Concat</span><span class="p">(</span><span class="n">Enumerable</span><span class="p">.</span><span class="nf">Repeat</span><span class="p">(</span><span class="s">"b"</span><span class="p">,</span> <span class="m">2</span><span class="p">));</span>
<span class="p">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C++' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C++.</code></pre>
</div>
</div></code-tab></code-tabs>
</div>
<div class="sect2">
<h3 id="visitor">Stream Visitor</h3>
<div class="paragraph">
<p>A stream visitor is another implementation of a stream receiver, which visits every key-value pair in the stream.</p>
</div>
<div class="paragraph">
<p>In the example below, we have 2 caches: "marketData", and "instruments". We receive market data ticks and put them into the streamer for the "marketData" cache. The stream visitor for the "marketData" streamer is invoked on the cluster member mapped to the particular market symbol. Upon receiving individual market ticks it updates the "instrument" cache with the latest market price.</p>
</div>
<div class="paragraph">
<p>Note, that we do not update the "marketData" cache at all, leaving it empty. We simply use it for colocated processing of the market data within the cluster directly on the node where the data is stored.</p>
</div>
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="kd">static</span> <span class="kd">class</span> <span class="nc">Instrument</span> <span class="o">{</span>
<span class="kd">final</span> <span class="nc">String</span> <span class="n">symbol</span><span class="o">;</span>
<span class="nc">Double</span> <span class="n">latest</span><span class="o">;</span>
<span class="nc">Double</span> <span class="n">high</span><span class="o">;</span>
<span class="nc">Double</span> <span class="n">low</span><span class="o">;</span>
<span class="kd">public</span> <span class="nf">Instrument</span><span class="o">(</span><span class="nc">String</span> <span class="n">symbol</span><span class="o">)</span> <span class="o">{</span>
<span class="k">this</span><span class="o">.</span><span class="na">symbol</span> <span class="o">=</span> <span class="n">symbol</span><span class="o">;</span>
<span class="o">}</span>
<span class="o">}</span>
<span class="kd">static</span> <span class="nc">Map</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Double</span><span class="o">&gt;</span> <span class="nf">getMarketData</span><span class="o">()</span> <span class="o">{</span>
<span class="c1">//populate market data somehow</span>
<span class="k">return</span> <span class="k">new</span> <span class="nc">HashMap</span><span class="o">&lt;&gt;();</span>
<span class="o">}</span>
<span class="nd">@Test</span>
<span class="kt">void</span> <span class="nf">streamVisitorExample</span><span class="o">()</span> <span class="o">{</span>
<span class="k">try</span> <span class="o">(</span><span class="nc">Ignite</span> <span class="n">ignite</span> <span class="o">=</span> <span class="nc">Ignition</span><span class="o">.</span><span class="na">start</span><span class="o">())</span> <span class="o">{</span>
<span class="nc">CacheConfiguration</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Double</span><span class="o">&gt;</span> <span class="n">mrktDataCfg</span> <span class="o">=</span> <span class="k">new</span> <span class="nc">CacheConfiguration</span><span class="o">&lt;&gt;(</span><span class="s">"marketData"</span><span class="o">);</span>
<span class="nc">CacheConfiguration</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Instrument</span><span class="o">&gt;</span> <span class="n">instCfg</span> <span class="o">=</span> <span class="k">new</span> <span class="nc">CacheConfiguration</span><span class="o">&lt;&gt;(</span><span class="s">"instruments"</span><span class="o">);</span>
<span class="c1">// Cache for market data ticks streamed into the system.</span>
<span class="nc">IgniteCache</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Double</span><span class="o">&gt;</span> <span class="n">mrktData</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">getOrCreateCache</span><span class="o">(</span><span class="n">mrktDataCfg</span><span class="o">);</span>
<span class="c1">// Cache for financial instruments.</span>
<span class="nc">IgniteCache</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Instrument</span><span class="o">&gt;</span> <span class="n">instCache</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">getOrCreateCache</span><span class="o">(</span><span class="n">instCfg</span><span class="o">);</span>
<span class="k">try</span> <span class="o">(</span><span class="nc">IgniteDataStreamer</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Double</span><span class="o">&gt;</span> <span class="n">mktStmr</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">dataStreamer</span><span class="o">(</span><span class="s">"marketData"</span><span class="o">))</span> <span class="o">{</span>
<span class="c1">// Note that we do not populate the 'marketData' cache (it remains empty).</span>
<span class="c1">// Instead we update the 'instruments' cache based on the latest market price.</span>
<span class="n">mktStmr</span><span class="o">.</span><span class="na">receiver</span><span class="o">(</span><span class="nc">StreamVisitor</span><span class="o">.</span><span class="na">from</span><span class="o">((</span><span class="n">cache</span><span class="o">,</span> <span class="n">e</span><span class="o">)</span> <span class="o">-&gt;</span> <span class="o">{</span>
<span class="nc">String</span> <span class="n">symbol</span> <span class="o">=</span> <span class="n">e</span><span class="o">.</span><span class="na">getKey</span><span class="o">();</span>
<span class="nc">Double</span> <span class="n">tick</span> <span class="o">=</span> <span class="n">e</span><span class="o">.</span><span class="na">getValue</span><span class="o">();</span>
<span class="nc">Instrument</span> <span class="n">inst</span> <span class="o">=</span> <span class="n">instCache</span><span class="o">.</span><span class="na">get</span><span class="o">(</span><span class="n">symbol</span><span class="o">);</span>
<span class="k">if</span> <span class="o">(</span><span class="n">inst</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span>
<span class="n">inst</span> <span class="o">=</span> <span class="k">new</span> <span class="nc">Instrument</span><span class="o">(</span><span class="n">symbol</span><span class="o">);</span>
<span class="c1">// Update instrument price based on the latest market tick.</span>
<span class="n">inst</span><span class="o">.</span><span class="na">high</span> <span class="o">=</span> <span class="nc">Math</span><span class="o">.</span><span class="na">max</span><span class="o">(</span><span class="n">inst</span><span class="o">.</span><span class="na">high</span><span class="o">,</span> <span class="n">tick</span><span class="o">);</span>
<span class="n">inst</span><span class="o">.</span><span class="na">low</span> <span class="o">=</span> <span class="nc">Math</span><span class="o">.</span><span class="na">min</span><span class="o">(</span><span class="n">inst</span><span class="o">.</span><span class="na">low</span><span class="o">,</span> <span class="n">tick</span><span class="o">);</span>
<span class="n">inst</span><span class="o">.</span><span class="na">latest</span> <span class="o">=</span> <span class="n">tick</span><span class="o">;</span>
<span class="c1">// Update the instrument cache.</span>
<span class="n">instCache</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">symbol</span><span class="o">,</span> <span class="n">inst</span><span class="o">);</span>
<span class="o">}));</span>
<span class="c1">// Stream market data into the cluster.</span>
<span class="nc">Map</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Double</span><span class="o">&gt;</span> <span class="n">marketData</span> <span class="o">=</span> <span class="n">getMarketData</span><span class="o">();</span>
<span class="k">for</span> <span class="o">(</span><span class="nc">Map</span><span class="o">.</span><span class="na">Entry</span><span class="o">&lt;</span><span class="nc">String</span><span class="o">,</span> <span class="nc">Double</span><span class="o">&gt;</span> <span class="n">tick</span> <span class="o">:</span> <span class="n">marketData</span><span class="o">.</span><span class="na">entrySet</span><span class="o">())</span>
<span class="n">mktStmr</span><span class="o">.</span><span class="na">addData</span><span class="o">(</span><span class="n">tick</span><span class="o">);</span>
<span class="o">}</span>
<span class="o">}</span>
<span class="o">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C#/.NET'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="csharp"><span class="k">class</span> <span class="nc">Instrument</span>
<span class="p">{</span>
<span class="k">public</span> <span class="k">readonly</span> <span class="kt">string</span> <span class="n">Symbol</span><span class="p">;</span>
<span class="k">public</span> <span class="kt">double</span> <span class="n">Latest</span> <span class="p">{</span> <span class="k">get</span><span class="p">;</span> <span class="k">set</span><span class="p">;</span> <span class="p">}</span>
<span class="k">public</span> <span class="kt">double</span> <span class="n">High</span> <span class="p">{</span> <span class="k">get</span><span class="p">;</span> <span class="k">set</span><span class="p">;</span> <span class="p">}</span>
<span class="k">public</span> <span class="kt">double</span> <span class="n">Low</span> <span class="p">{</span> <span class="k">get</span><span class="p">;</span> <span class="k">set</span><span class="p">;</span> <span class="p">}</span>
<span class="k">public</span> <span class="nf">Instrument</span><span class="p">(</span><span class="kt">string</span> <span class="n">symbol</span><span class="p">)</span>
<span class="p">{</span>
<span class="k">this</span><span class="p">.</span><span class="n">Symbol</span> <span class="p">=</span> <span class="n">symbol</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">private</span> <span class="k">static</span> <span class="n">Dictionary</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">double</span><span class="p">&gt;</span> <span class="nf">getMarketData</span><span class="p">()</span>
<span class="p">{</span>
<span class="c1">//populate market data somehow</span>
<span class="k">return</span> <span class="k">new</span> <span class="n">Dictionary</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">double</span><span class="p">&gt;</span>
<span class="p">{</span>
<span class="p">[</span><span class="s">"foo"</span><span class="p">]</span> <span class="p">=</span> <span class="m">1.0</span><span class="p">,</span>
<span class="p">[</span><span class="s">"foo"</span><span class="p">]</span> <span class="p">=</span> <span class="m">2.0</span><span class="p">,</span>
<span class="p">[</span><span class="s">"foo"</span><span class="p">]</span> <span class="p">=</span> <span class="m">3.0</span>
<span class="p">};</span>
<span class="p">}</span>
<span class="k">public</span> <span class="k">static</span> <span class="k">void</span> <span class="nf">StreamVisitorDemo</span><span class="p">()</span>
<span class="p">{</span>
<span class="kt">var</span> <span class="n">ignite</span> <span class="p">=</span> <span class="n">Ignition</span><span class="p">.</span><span class="nf">Start</span><span class="p">(</span><span class="k">new</span> <span class="n">IgniteConfiguration</span>
<span class="p">{</span>
<span class="n">DiscoverySpi</span> <span class="p">=</span> <span class="k">new</span> <span class="n">TcpDiscoverySpi</span>
<span class="p">{</span>
<span class="n">LocalPort</span> <span class="p">=</span> <span class="m">48500</span><span class="p">,</span>
<span class="n">LocalPortRange</span> <span class="p">=</span> <span class="m">20</span><span class="p">,</span>
<span class="n">IpFinder</span> <span class="p">=</span> <span class="k">new</span> <span class="n">TcpDiscoveryStaticIpFinder</span>
<span class="p">{</span>
<span class="n">Endpoints</span> <span class="p">=</span> <span class="k">new</span><span class="p">[]</span>
<span class="p">{</span>
<span class="s">"127.0.0.1:48500..48520"</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="kt">var</span> <span class="n">mrktDataCfg</span> <span class="p">=</span> <span class="k">new</span> <span class="nf">CacheConfiguration</span><span class="p">(</span><span class="s">"marketData"</span><span class="p">);</span>
<span class="kt">var</span> <span class="n">instCfg</span> <span class="p">=</span> <span class="k">new</span> <span class="nf">CacheConfiguration</span><span class="p">(</span><span class="s">"instruments"</span><span class="p">);</span>
<span class="c1">// Cache for market data ticks streamed into the system</span>
<span class="kt">var</span> <span class="n">mrktData</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetOrCreateCache</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">double</span><span class="p">&gt;(</span><span class="n">mrktDataCfg</span><span class="p">);</span>
<span class="c1">// Cache for financial instruments</span>
<span class="kt">var</span> <span class="n">instCache</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetOrCreateCache</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="n">Instrument</span><span class="p">&gt;(</span><span class="n">instCfg</span><span class="p">);</span>
<span class="k">using</span> <span class="p">(</span><span class="kt">var</span> <span class="n">mktStmr</span> <span class="p">=</span> <span class="n">ignite</span><span class="p">.</span><span class="n">GetDataStreamer</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">double</span><span class="p">&gt;(</span><span class="s">"marketData"</span><span class="p">))</span>
<span class="p">{</span>
<span class="c1">// Note that we do not populate 'marketData' cache (it remains empty).</span>
<span class="c1">// Instead we update the 'instruments' cache based on the latest market price.</span>
<span class="n">mktStmr</span><span class="p">.</span><span class="n">Receiver</span> <span class="p">=</span> <span class="k">new</span> <span class="n">StreamVisitor</span><span class="p">&lt;</span><span class="kt">string</span><span class="p">,</span> <span class="kt">double</span><span class="p">&gt;((</span><span class="n">cache</span><span class="p">,</span> <span class="n">e</span><span class="p">)</span> <span class="p">=&gt;</span>
<span class="p">{</span>
<span class="kt">var</span> <span class="n">symbol</span> <span class="p">=</span> <span class="n">e</span><span class="p">.</span><span class="n">Key</span><span class="p">;</span>
<span class="kt">var</span> <span class="n">tick</span> <span class="p">=</span> <span class="n">e</span><span class="p">.</span><span class="n">Value</span><span class="p">;</span>
<span class="n">Instrument</span> <span class="n">inst</span> <span class="p">=</span> <span class="n">instCache</span><span class="p">.</span><span class="nf">Get</span><span class="p">(</span><span class="n">symbol</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="n">inst</span> <span class="p">==</span> <span class="k">null</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">inst</span> <span class="p">=</span> <span class="k">new</span> <span class="nf">Instrument</span><span class="p">(</span><span class="n">symbol</span><span class="p">);</span>
<span class="p">}</span>
<span class="c1">// Update instrument price based on the latest market tick.</span>
<span class="n">inst</span><span class="p">.</span><span class="n">High</span> <span class="p">=</span> <span class="n">Math</span><span class="p">.</span><span class="nf">Max</span><span class="p">(</span><span class="n">inst</span><span class="p">.</span><span class="n">High</span><span class="p">,</span> <span class="n">tick</span><span class="p">);</span>
<span class="n">inst</span><span class="p">.</span><span class="n">Low</span> <span class="p">=</span> <span class="n">Math</span><span class="p">.</span><span class="nf">Min</span><span class="p">(</span><span class="n">inst</span><span class="p">.</span><span class="n">Low</span><span class="p">,</span> <span class="n">tick</span><span class="p">);</span>
<span class="n">inst</span><span class="p">.</span><span class="n">Latest</span> <span class="p">=</span> <span class="n">tick</span><span class="p">;</span>
<span class="p">});</span>
<span class="kt">var</span> <span class="n">marketData</span> <span class="p">=</span> <span class="nf">getMarketData</span><span class="p">();</span>
<span class="k">foreach</span> <span class="p">(</span><span class="kt">var</span> <span class="n">tick</span> <span class="k">in</span> <span class="n">marketData</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">mktStmr</span><span class="p">.</span><span class="nf">AddData</span><span class="p">(</span><span class="n">tick</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">mktStmr</span><span class="p">.</span><span class="nf">Flush</span><span class="p">();</span>
<span class="n">Console</span><span class="p">.</span><span class="nf">Write</span><span class="p">(</span><span class="n">instCache</span><span class="p">.</span><span class="nf">Get</span><span class="p">(</span><span class="s">"foo"</span><span class="p">));</span>
<span class="p">}</span>
<span class="p">}</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C++' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C++.</code></pre>
</div>
</div></code-tab></code-tabs>
</div>
</div>
</div>
<div class="sect1">
<h2 id="configuring-data-streamer-thread-pool-size">Configuring Data Streamer Thread Pool Size</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The data streamer thread pool is dedicated to process batches coming from the data streamers.</p>
</div>
<div class="paragraph">
<p>The default pool size is <code>max(8, total number of cores)</code>.
Use <code>IgniteConfiguration.setDataStreamerThreadPoolSize(&#8230;&#8203;)</code> to change the pool size.</p>
</div>
<code-tabs><code-tab data-tab='XML'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="xml"><span class="nt">&lt;bean</span> <span class="na">class=</span><span class="s">"org.apache.ignite.configuration.IgniteConfiguration"</span><span class="nt">&gt;</span>
<span class="nt">&lt;property</span> <span class="na">name=</span><span class="s">"dataStreamerThreadPoolSize"</span> <span class="na">value=</span><span class="s">"10"</span><span class="nt">/&gt;</span>
<span class="c">&lt;!-- other properties --&gt;</span>
<span class="nt">&lt;/bean&gt;</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="nc">IgniteConfiguration</span> <span class="n">cfg</span> <span class="o">=</span> <span class="k">new</span> <span class="nc">IgniteConfiguration</span><span class="o">();</span>
<span class="n">cfg</span><span class="o">.</span><span class="na">setDataStreamerThreadPoolSize</span><span class="o">(</span><span class="mi">10</span><span class="o">);</span>
<span class="nc">Ignite</span> <span class="n">ignite</span> <span class="o">=</span> <span class="nc">Ignition</span><span class="o">.</span><span class="na">start</span><span class="o">(</span><span class="n">cfg</span><span class="o">);</span></code></pre>
</div>
</div></code-tab><code-tab data-tab='C#/.NET' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C#/.NET. You can use XML configuration.</code></pre>
</div>
</div></code-tab><code-tab data-tab='C++' data-unavailable='true'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code>This API is not presently available for C++. You can use XML configuration.</code></pre>
</div>
</div></code-tab></code-tabs>
</div>
</div>
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© 2024 The Apache Software Foundation.<br/>
Apache, Apache Ignite, the Apache feather and the Apache Ignite logo are either registered trademarks or trademarks of The Apache Software Foundation.
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<li><a href="#overview">Overview</a></li>
<li><a href="#usage">Usage</a></li>
<li><a href="#limitations">Limitations</a></li>
<li><a href="#receivers">Streamer receivers.</a></li>
<li><a href="#overwritting">Overwritting data.</a>
<ul class="sectlevel2">
<li><a href="#transfomer">Stream Transformer</a></li>
<li><a href="#visitor">Stream Visitor</a></li>
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