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| <div class="collapse" id="collapse_background"> |
| <li><a href="/docs/Background/TheChallenge.html">•The Challenge</a></li> |
| <li><a href="/docs/Background/SketchOrigins.html">•Sketch Origins</a></li> |
| <li><a href="/docs/Background/SketchElements.html">•Sketch Elements</a></li> |
| <li><a href="/docs/Background/Presentations.html">•Presentations</a></li> |
| <li><a href="https://github.com/apache/datasketches-website/tree/master/docs/pdf/DataSketches_deck.pdf">•Overview Slide Deck</a></li> |
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| <li><a href="/docs/Architecture/MajorSketchFamilies.html">•The Major Sketch Families</a></li> |
| <li><a href="/docs/Architecture/LargeScale.html">•Large Scale Computing</a></li> |
| <li><a href="/docs/Architecture/KeyFeatures.html">•Key Features</a></li> |
| <li><a href="/docs/Architecture/SketchFeaturesMatrix.html">•Sketch Features Matrix</a></li> |
| <li><a href="/docs/Architecture/Components.html">•Components</a></li> |
| <li><a href="/docs/Architecture/SketchesByComponent.html">•Sketches by Component</a></li> |
| <li><a href="/docs/Architecture/SketchCriteria.html">•Sketch Criteria</a></li> |
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| <p id="memory-component"> |
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| <li><a href="/docs/Memory/MemoryComponent.html">•Memory Component</a></li> |
| <li><a href="/docs/Memory/MemoryPerformance.html">•Memory Component Performance</a></li> |
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| <li><a href="/docs/Architecture/OrderSensitivity.html">•Notes on Order Sensitivity</a></li> |
| <li><a href="/docs/Architecture/Concurrency.html">•Notes on Concurrency</a></li> |
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| <li><a href="/docs/DistinctCountFeaturesMatrix.html">•Features Matrix</a></li> |
| <li><a href="/docs/DistinctCountMeritComparisons.html">•Figures-of-Merit Comparison</a></li> |
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| <p id="cpc-sketches"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_cpc_sketches">CPC Sketches</a> |
| </p> |
| <div class="collapse" id="collapse_cpc_sketches"> |
| <li><a href="/docs/CPC/CPC.html">•CPC Sketch</a></li> |
| <li><a href="/docs/CPC/CpcPerformance.html">•CPC Sketch Performance</a></li> |
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| <a data-toggle="collapse" class="menu collapsed" href="#collapse_cpc_examples">CPC Examples</a> |
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| <li><a href="/docs/CPC/CpcJavaExample.html">•CPC Sketch Java Example</a></li> |
| <li><a href="/docs/CPC/CpcCppExample.html">•CPC Sketch C++ Example</a></li> |
| <li><a href="/docs/CPC/CpcPigExample.html">•CPC Sketch Pig UDFs</a></li> |
| <li><a href="/docs/CPC/CpcHiveExample.html">•CPC Sketch Hive UDFs</a></li> |
| </div> |
| </div> |
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| <p id="hyperloglog-sketches"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_hyperloglog_sketches">HyperLogLog Sketches</a> |
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| <li><a href="/docs/HLL/HLL.html">•HLL Sketch</a></li> |
| <li><a href="/docs/HLL/HllMap.html">•HLL Map Sketch</a></li> |
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| <p id="hll-examples"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_hll_examples">HLL Examples</a> |
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| <li><a href="/docs/HLL/HllJavaExample.html">•HLL Sketch Java Example</a></li> |
| <li><a href="/docs/HLL/HllCppExample.html">•HLL Sketch C++ Example</a></li> |
| <li><a href="/docs/HLL/HllPigUDFs.html">•HLL Sketch Pig UDFs</a></li> |
| <li><a href="/docs/HLL/HllHiveUDFs.html">•HLL Sketch Hive UDFs</a></li> |
| </div> |
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| <p id="hll-studies"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_hll_studies">HLL Studies</a> |
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| <div class="collapse" id="collapse_hll_studies"> |
| <li><a href="/docs/HLL/HllPerformance.html">•HLL Sketch Performance</a></li> |
| <li><a href="/docs/HLL/Hll_vs_CS_Hllpp.html">•HLL vs Clearspring HLL++</a></li> |
| <li><a href="/docs/HLL/HllSketchVsDruidHyperLogLogCollector.html">•HLL Sketch vs Druid HyperLogLogCollector</a></li> |
| </div> |
| </div> |
| |
| <p id="theta-sketches"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_theta_sketches">Theta Sketches</a> |
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| <div class="collapse" id="collapse_theta_sketches"> |
| <li><a href="/docs/Theta/ThetaSketchFramework.html">•Theta Sketch Framework</a></li> |
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| <p id="theta-examples"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_theta_examples">Theta Examples</a> |
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| <div class="collapse" id="collapse_theta_examples"> |
| <li><a href="/docs/Theta/ConcurrentThetaSketch.html">•Concurrent Theta Sketch</a></li> |
| <li><a href="/docs/Theta/ThetaJavaExample.html">•Theta Sketch Java Example</a></li> |
| <li><a href="/docs/Theta/ThetaSparkExample.html">•Theta Sketch Spark Example</a></li> |
| <li><a href="/docs/Theta/ThetaPigUDFs.html">•Theta Sketch Pig UDFs</a></li> |
| <li><a href="/docs/Theta/ThetaHiveUDFs.html">•Theta Sketch Hive UDFs</a></li> |
| </div> |
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| <p id="kmv-tutorial"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_kmv_tutorial">KMV Tutorial</a> |
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| <div class="collapse" id="collapse_kmv_tutorial"> |
| <li><a href="/docs/Theta/InverseEstimate.html">•The Inverse Estimate</a></li> |
| <li><a href="/docs/Theta/KMVempty.html">•Empty Sketch</a></li> |
| <li><a href="/docs/Theta/KMVfirstEst.html">•First Estimator</a></li> |
| <li><a href="/docs/Theta/KMVbetterEst.html">•Better Estimator</a></li> |
| <li><a href="/docs/Theta/KMVrejection.html">•Rejection Rules</a></li> |
| <li><a href="/docs/Theta/KMVupdateVkth.html">•Update V(kth) Rule</a></li> |
| </div> |
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| <p id="set-operations-and-p-sampling"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_set_operations_and_p-sampling">Set Operations and P-sampling</a> |
| </p> |
| <div class="collapse" id="collapse_set_operations_and_p-sampling"> |
| <li><a href="/docs/Theta/ThetaSketchSetOps.html">•Set Operations</a></li> |
| <li><a href="/docs/Theta/ThetaSetOpsCornerCases.html">•Model & Test Set Operations</a></li> |
| <li><a href="/docs/Theta/ThetaPSampling.html">•<i>p</i>-Sampling</a></li> |
| </div> |
| |
| <p id="accuracy"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_accuracy">Accuracy</a> |
| </p> |
| <div class="collapse" id="collapse_accuracy"> |
| <li><a href="/docs/Theta/ThetaAccuracy.html">•Basic Accuracy</a></li> |
| <li><a href="/docs/Theta/ThetaAccuracyPlots.html">•Accuracy Plots</a></li> |
| <li><a href="/docs/Theta/ThetaErrorTable.html">•Relative Error Table</a></li> |
| <li><a href="/docs/Theta/ThetaSketchSetOpsAccuracy.html">•SetOp Accuracy</a></li> |
| <li><a href="/docs/Theta/AccuracyOfDifferentKUnions.html">•Unions With Different k</a></li> |
| </div> |
| |
| <p id="size"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_size">Size</a> |
| </p> |
| <div class="collapse" id="collapse_size"> |
| <li><a href="/docs/Theta/ThetaSize.html">•Theta Sketch Size</a></li> |
| </div> |
| |
| <p id="speed"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_speed">Speed</a> |
| </p> |
| <div class="collapse" id="collapse_speed"> |
| <li><a href="/docs/Theta/ThetaUpdateSpeed.html">•Update Speed</a></li> |
| <li><a href="/docs/Theta/ThetaMergeSpeed.html">•Merge Speed</a></li> |
| </div> |
| |
| <p id="theta-sketch-theory"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_theta_sketch_theory">Theta Sketch Theory</a> |
| </p> |
| <div class="collapse" id="collapse_theta_sketch_theory"> |
| <li><a href="https://github.com/apache/datasketches-website/tree/master/docs/pdf/ThetaSketchFramework.pdf">•Theta Sketch Framework (PDF)</a></li> |
| <li><a href="https://github.com/apache/datasketches-website/tree/master/docs/pdf/ThetaSketchEquations.pdf">•Theta Sketch Equations (PDF)</a></li> |
| <li><a href="https://github.com/apache/datasketches-website/tree/master/docs/pdf/DataSketches.pdf">•DataSketches (PDF)</a></li> |
| <li><a href="/docs/Theta/ThetaConfidenceIntervals.html">•Confidence Intervals Notes</a></li> |
| <li><a href="/docs/Theta/ThetaMergingAlgorithm.html">•Merging Algorithm Notes</a></li> |
| <li><a href="/docs/Theta/ThetaReferences.html">•Theta References</a></li> |
| </div> |
| </div> |
| |
| <p id="tuple-sketches"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_tuple_sketches">Tuple Sketches</a> |
| </p> |
| <div class="collapse" id="collapse_tuple_sketches"> |
| <li><a href="/docs/Tuple/TupleOverview.html">•Tuple Overview</a></li> |
| |
| <p id="tuple-examples"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_tuple_examples">Tuple Examples</a> |
| </p> |
| <div class="collapse" id="collapse_tuple_examples"> |
| <li><a href="/docs/Tuple/TupleJavaExample.html">•Tuple Java Example</a></li> |
| <li><a href="/docs/Tuple/TupleEngagementExample.html">•Tuple Engagement Example</a></li> |
| <li><a href="/docs/Tuple/TuplePigUDFs.html">•Tuple Pig UDFs</a></li> |
| <li><a href="/docs/Tuple/TupleHiveUDFs.html">•Tuple Hive UDFs</a></li> |
| </div> |
| </div> |
| </div> |
| |
| <p id="most-frequent"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_most_frequent">Most Frequent</a> |
| </p> |
| <div class="collapse" id="collapse_most_frequent"> |
| <li><a href="/docs/Frequency/FrequencySketchesOverview.html">•Frequency Sketches Overview</a></li> |
| |
| <p id="frequent-item-sketches"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_frequent_item_sketches">Frequent Item Sketches</a> |
| </p> |
| <div class="collapse" id="collapse_frequent_item_sketches"> |
| <li><a href="/docs/Frequency/FrequentItemsOverview.html">•Frequent Items Overview</a></li> |
| <li><a href="/docs/Frequency/FrequentItemsErrorTable.html">•Frequent Items Error Table</a></li> |
| <li><a href="/docs/Frequency/FrequentItemsReferences.html">•Frequent Items References</a></li> |
| <li><a href="/docs/Frequency/FrequentItemsPerformance.html">•Frequent Items Performance</a></li> |
| |
| <p id="most-frequent-examples"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_most_frequent_examples">Most Frequent Examples</a> |
| </p> |
| <div class="collapse" id="collapse_most_frequent_examples"> |
| <li><a href="/docs/Frequency/FrequentItemsJavaExample.html">•Frequent Items Java Example</a></li> |
| <li><a href="/docs/Frequency/FrequentItemsCppExample.html">•Frequent Items C++ Example</a></li> |
| <li><a href="/docs/Frequency/FrequentItemsPigUDFs.html">•Frequent Items Pig UDFs</a></li> |
| <li><a href="/docs/Frequency/FrequentItemsHiveUDFs.html">•Frequent Items Hive UDFs</a></li> |
| </div> |
| </div> |
| |
| <p id="frequent-distinct-sketches"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_frequent_distinct_sketches">Frequent Distinct Sketches</a> |
| </p> |
| <div class="collapse" id="collapse_frequent_distinct_sketches"> |
| <li><a href="/docs/Frequency/FrequentDistinctTuplesSketch.html">•Frequent Distinct Tuples Sketch</a></li> |
| </div> |
| </div> |
| |
| <p id="quantiles-and-histograms"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_quantiles_and_histograms">Quantiles And Histograms</a> |
| </p> |
| <div class="collapse" id="collapse_quantiles_and_histograms"> |
| <li><a href="/docs/Quantiles/SketchingQuantilesAndRanksTutorial.html">•Quantiles and Ranks Tutorial</a></li> |
| <li><a href="/docs/Quantiles/QuantilesOverview.html">•Quantiles Overview</a></li> |
| <li><a href="/docs/KLL/KLLSketch.html">•KLL Floats sketch</a></li> |
| <li><a href="/docs/KLL/KLLAccuracyAndSize.html">•KLL Sketch Accuracy and Size</a></li> |
| <li><a href="/docs/REQ/ReqSketch.html">•REQ Floats sketch</a></li> |
| <li><a href="/docs/Quantiles/OrigQuantilesSketch.html">•Original QuantilesSketch</a></li> |
| |
| <p id="quantiles-examples"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_quantiles_examples">Quantiles Examples</a> |
| </p> |
| <div class="collapse" id="collapse_quantiles_examples"> |
| <li><a href="/docs/Quantiles/QuantilesJavaExample.html">•Quantiles Sketch Java Example</a></li> |
| <li><a href="/docs/KLL/KLLCppExample.html">•KLL Quantiles Sketch C++ Example</a></li> |
| <li><a href="/docs/Quantiles/QuantilesPigUDFs.html">•Quantiles Sketch Pig UDFs</a></li> |
| <li><a href="/docs/Quantiles/QuantilesHiveUDFs.html">•Quantiles Sketch Hive UDFs</a></li> |
| </div> |
| |
| <p id="quantiles-studies"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_quantiles_studies">Quantiles Studies</a> |
| </p> |
| <div class="collapse" id="collapse_quantiles_studies"> |
| <li><a href="/docs/QuantilesStudies/DruidApproxHistogramStudy.html">•Druid Approximate Histogram</a></li> |
| <li><a href="/docs/QuantilesStudies/MomentsSketchStudy.html">•Moments Sketch Study</a></li> |
| <li><a href="/docs/QuantilesStudies/QuantilesStreamAStudy.html">•Quantiles StreamA Study</a></li> |
| <li><a href="/docs/QuantilesStudies/ExactQuantiles.html">•Exact Quantiles for Studies</a></li> |
| </div> |
| |
| <p id="quantiles-sketch-theory"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_quantiles_sketch_theory">Quantiles Sketch Theory</a> |
| </p> |
| <div class="collapse" id="collapse_quantiles_sketch_theory"> |
| <li><a href="https://github.com/apache/datasketches-website/tree/master/docs/pdf/Quantiles_KLL.pdf">•Optimal Quantile Approximation in Streams</a></li> |
| <li><a href="/docs/Quantiles/QuantilesReferences.html">•Quantiles References</a></li> |
| </div> |
| </div> |
| |
| <p id="sampling"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_sampling">Sampling</a> |
| </p> |
| <div class="collapse" id="collapse_sampling"> |
| <li><a href="/docs/Sampling/ReservoirSampling.html">•Reservoir Sampling</a></li> |
| <li><a href="/docs/Sampling/ReservoirSamplingPerformance.html">•Reservoir Sampling Performance</a></li> |
| <li><a href="/docs/Sampling/VarOptSampling.html">•VarOpt Sampling</a></li> |
| |
| <p id="sampling-examples"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_sampling_examples">Sampling Examples</a> |
| </p> |
| <div class="collapse" id="collapse_sampling_examples"> |
| <li><a href="/docs/Sampling/ReservoirSamplingJava.html">•Reservoir Sampling Java Example</a></li> |
| <li><a href="/docs/Sampling/ReservoirSamplingPigUDFs.html">•Reservoir Sampling Pig UDFs</a></li> |
| <li><a href="/docs/Sampling/VarOptSamplingJava.html">•VarOpt Sampling Java Example</a></li> |
| <li><a href="/docs/Sampling/VarOptPigUDFs.html">•VarOpt Sampling Pig UDFs</a></li> |
| </div> |
| </div> |
| </div> |
| |
| <p id="system-integrations"> |
| <a data-toggle="collapse" class="menu collapsed" href="#collapse_system_integrations">System Integrations</a> |
| </p> |
| <div class="collapse" id="collapse_system_integrations"> |
| <li><a href="/docs/SystemIntegrations/ApacheDruidIntegration.html">•Using Sketches in ApacheDruid</a></li> |
| <li><a href="/docs/SystemIntegrations/ApacheHiveIntegration.html">•Using Sketches in Apache Hive</a></li> |
| <li><a href="/docs/SystemIntegrations/ApachePigIntegration.html">•Using Sketches in Apache Pig</a></li> |
| <li><a href="/docs/SystemIntegrations/PostgreSQLIntegration.html">•Using Sketches in PostgreSQL</a></li> |
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| <li><a href="/docs/Community/NewCommitterProcess.html">•Committer Process</a></li> |
| <li><a href="/docs/Community/ReleaseProcessForCppComponents.html">•Release Process For CPP Components</a></li> |
| <li><a href="/docs/Community/ReleaseProcessForJavaComponents.html">•Release Process For Java Components</a></li> |
| <li><a href="/docs/Community/Transitioning.html">•Transitioning from prior GitHub Site</a></li> |
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| <h2 id="designed-for-large-scale-computing-systems">Designed for Large-scale Computing Systems</h2> |
| |
| <h3 id="multiple-languages">Multiple Languages</h3> |
| |
| <ul> |
| <li>The DataSketches library is now available in three languages, Java, C++, and Python. A fourth language, Go, is in development.</li> |
| </ul> |
| |
| <h3 id="compatibility-across-languages-software-versions-and-binary-serialization-versions">Compatibility Across Languages, Software Versions And Binary Serialization Versions</h3> |
| <p>Large-scale computing environments may have a mix of various platforms utilizing different programming languages each with the possiblity of using different Software Versions of our DataSketches library. Cross version compatibility of software is a challenge that all platforms face in general, and it is up to the platform maintainers to keep their software up-to-date. This not new and not different with the DataSketches library.</p> |
| |
| <p>Nonetheless, it our goal to strive to make it as easy as practically possible to serialize our sketches in one of our supported languages on one platform and to be deserialized in a different supported language, potentially on a different, even remote platform, and perhaps much later in time.</p> |
| |
| <p>With this goal in mind, here are some of the key strategic decisions we have made in the development of the DataSketches library.</p> |
| |
| <h4 id="two-levels-of-versioning">Two levels of versioning.</h4> |
| |
| <ul> |
| <li> |
| <p><strong>Software Version:</strong> This is the release version, published via Apache.org and specified in the POM file or equivalent. This can change relatively frequently based on bug fixes and introduction of new capabilities. We follow the principles of <em>Semantic Versioning</em> as specified by <a href="https://semver.org">semver.org</a>.</p> |
| </li> |
| <li> |
| <p><strong>Serialization Version:</strong> (<em>SerVer</em>) This is a small integer placed in the preamble of the serialized byte array that indicates the version of the serialized structure for the sketch. This is very similar to Java’s <a href="https://en.wikipedia.org/wiki/Java_class_file"><em>Class File Format Version</em></a>. A single <em>SerVer</em> may represent multiple structures all based on the same sketch when stored in different states, e.g., <em>Single Item</em>, <em>Compact</em>, <em>Updatable</em>, etc). This <em>SerVer</em> changes very rarely, if at all. Of all of our sketches, only a few, e.g., Theta, KLL and Sampling, have had more than one <em>SerVer</em> over time. There are and will be many <em>Software Versions</em> of the same sketch that still use the same <em>SerVer</em>. When we have to update the <em>SerVer</em>, we provide the capability in the <em>Software Version</em> of the code associated with the new <em>SerVer</em> the ability to read and convert the old <em>SerVer</em> to the new <em>SerVer</em>. This is why our newest <em>Software Versions</em> can still read and interpret older <em>SerVer</em> serialized sketches that go back to when our project was started at Yahoo (2012), and before we went open-source (2015). Technically speaking this can be described as <em>Backward-Transient</em> compatibility <a href="https://docs.confluent.io/platform/current/schema-registry/fundamentals/schema-evolution.html">Schema Evolution and Compatibility</a> and <a href="https://en.wikipedia.org/wiki/Schema_evolution">Schema Evolution</a>.</p> |
| </li> |
| </ul> |
| |
| <p>From the user’s perspective, as long as the <em>SerVer</em> is the same, older <em>Software Versions</em> should be able to read sketch images created by newer <em>Software Versions</em>. But the APIs may be different, obviously. An older <em>Software Version</em> will not be able to take advantage of new features introduced in new <em>Software Versions</em>, but it should be able to do what it did before. In other words, there will be no loss of access to the serialized sketch and the older <em>Software Version</em> capabilities. A user should not need to access the <em>SerVer</em>, nonetheless it is always stored in index one of the serialized image. If a sketch is presented with a <em>SerVer</em> that it is not compatible with, the sketch should throw an exception and say what the problem is, just like Java does with its <em>Class File Format Versions</em>.</p> |
| |
| <p>Sketches requiring user-written custom serialize/deserialize code rely on users to port that custom code themselves for cross-version, cross-language, and cross-platform compatibility.</p> |
| |
| <h4 id="the-serialized-image-of-a-sketch">The Serialized Image of a Sketch</h4> |
| <ul> |
| <li>The structure (or image) of a serialized sketch is independent of the language from which it was created.</li> |
| <li>The sketch image only contains little-endian primitives, such as int64, int32, int16, int8, double-64, float-32, UTF-8 strings, and simple array structures of those. While these serialized primitives between languages may not be strictly equal they can be interpreted to be logically equivalent. We do not support big-endian serialization.</li> |
| <li>The sketch image is unique for each type of sketch.</li> |
| <li>Simply speaking, a sketch image can be viewed as a blob of bytes, which is easily stored and easily transported using many different protocols, including Protobuf, Avro, Thrift, Byte64, etc.</li> |
| </ul> |
| |
| <p>As a result, sketches serialized in one supported language can be interpreted by a different supported language, with the caveat that due to language differences, availability of resources, and time to develop, not all sketches may be available in all languages at the same time.</p> |
| |
| <h3 id="easy-integration-with-minimal-dependencies">Easy Integration with Minimal Dependencies</h3> |
| <p>We strive to make our sketch library easy to integrate into larger systems by keeping the number of external dependencies at a minimum.</p> |
| |
| <ul> |
| <li><a href="https://datasketches.apache.org/docs/Community/Downloads.html">Java Core</a> |
| <ul> |
| <li>The Java core library (including Memory) has no dependencies outside of the Java JVM at runtime allowing simple integration into virtually any Java based system environment.</li> |
| <li>All of the Java components and artifacts are Maven Deployable and registered with <a href="https://search.maven.org/classic/#search%7Cga%7C1%7Cg%3A%22org.apache.datasketches%22">The Central Repository</a></li> |
| </ul> |
| </li> |
| <li><a href="https://datasketches.apache.org/docs/Community/Downloads.html">C++ Core</a> |
| <ul> |
| <li>The C++ core is written as all header files allowing easy integration into a wide range of operating system environments.</li> |
| </ul> |
| </li> |
| <li><a href="https://github.com/apache/datasketches-cpp/tree/master/python">Python</a> |
| <ul> |
| <li>The C++ Core is extended using the python binding library <a href="https://github.com/pybind/pybind11">pybind11</a> enabling high performance operation from Python.</li> |
| </ul> |
| </li> |
| </ul> |
| |
| <h3 id="speed">Speed</h3> |
| <ul> |
| <li> |
| <p>These single-pass, “one-touch” algorithms are <i>fast (<a href="https://datasketches.apache.org/docs/Theta/ThetaUpdateSpeed.html">see example</a>)</i> to enable real-time processing capability.</p> |
| </li> |
| <li> |
| <p>Sketches can be represented in an updatable or compact form. The compact form is smaller, immutable and faster to merge.</p> |
| </li> |
| <li> |
| <p>Some of the Java sketches have been designed to be instantiated and operated <i>off-heap</i>, whicn eliminates costly serialization and deserialization.</p> |
| </li> |
| <li> |
| <p>The sketch data structures are “additive” and embarrassingly parallelizable. Sketches can be merged without losing accuracy.</p> |
| </li> |
| </ul> |
| |
| <h3 id="system-integrations">System Integrations</h3> |
| <p>The following are system integrations that we have been involved with, but there are many more platform integrations out there that were performed by the individual platform teams.</p> |
| |
| <ul> |
| <li> |
| <p><a href="https://datasketches.apache.org/docs/SystemIntegrations/ApacheDruidIntegration.html">Druid Integration</a></p> |
| </li> |
| <li> |
| <p><a href="https://datasketches.apache.org/docs/SystemIntegrations/ApacheHiveIntegration.html">Apache Hive</a></p> |
| </li> |
| <li> |
| <p><a href="https://datasketches.apache.org/docs/SystemIntegrations/ApachePigIntegration.html">Apache Pig</a></p> |
| </li> |
| <li> |
| <p><a href="https://datasketches.apache.org/docs/SystemIntegrations/PostgreSQLIntegration.html">PostgreSQL</a></p> |
| </li> |
| <li> |
| <p><a href="https://datasketches.apache.org/docs/Theta/ThetaSparkExample.html">Spark Examples</a></p> |
| </li> |
| </ul> |
| |
| <h3 id="specific-sketch-features-for-large-data">Specific Sketch Features for Large Data</h3> |
| <ul> |
| <li> |
| <p><b>Hash Seed Handling</b>. Additional protection for managing hash seeds which is |
| particularly important when processing sensitive user identifiers. Available with Theta Sketches.</p> |
| </li> |
| <li> |
| <p><a href="/docs/Theta/ThetaPSampling.html">Pre-Sampling</a>. Built-in up-front sampling for cases where additional |
| contol is required to limit overall memory consumption when dealing with millions of sketches. Available with Theta Sketches.</p> |
| </li> |
| <li> |
| <p><a href="/docs/Memory/MemoryComponent.html">Memory Component</a>. |
| Large query systems often require their own heaps outside the JVM in order to better manage garbage collection latencies. |
| The Java sketches utilize this powerful component.</p> |
| </li> |
| <li> |
| <p>Built-in <b>Upper-Bound and Lower-Bound estimators</b>. |
| You are never in the dark about how good of an estimate the sketch is providing. |
| Nearly all the sketches are able to estimate the upper and lower bounds of the estimate given a |
| confidence level.</p> |
| </li> |
| <li> |
| <p>User configurable trade-offs of accuracy vs. storage space as well as other performance |
| tuning options.</p> |
| </li> |
| <li> |
| <p><b>Small Footprint Per Sketch</b>. The in-memory run-time and storage footprint for both |
| row and column oriented storage are minimized with compact binary representations, which are much smaller |
| than the raw input stream and with a well defined upper bound of size.</p> |
| </li> |
| </ul> |
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| Licensed under the Apache License, Version 2.0. All Rights Reserved. |
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