book

Practical MongoDB Aggregations

Name: Practical MongoDB Aggregations
Author: Paul Done
ISBN: 9781835080641

by Paul Done

September 2023

Intermediate to advanced

312 pages

5h 38m

English

Packt Publishing

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First edition
Acknowledgements
Foreword
Preface
How will this book help you?Who this book is forWhat this book coversTo get the most out of this bookDownload the example code filesConventions usedGet in touchDownload a free PDF copy of this book
Chapter 1: MongoDB Aggregations Explained
What is the MongoDB aggregation framework?What is the MongoDB aggregation language?What do developers use the aggregation framework for?A short history of MongoDB aggregationsAggregation capabilities in MongoDB server releasesGetting goingSetting up your environmentDatabaseClient toolGetting further helpSummary
Part 1: Guiding Tips and Principles
Chapter 2: Optimizing Pipelines for Productivity
Embrace composability for increased productivityGuiding principles to promote composabilityUsing macro functionsSo, what's the best way of factoring out code?Better alternatives for a projection stageWhen to use $set and $unsetWhen to use $projectThe hidden danger of $projectKey projection takeawaysSummary
Chapter 3: Optimizing Pipelines for Performance
Using explain plans to identify performance bottlenecksViewing an explain planUnderstanding the explain planGuidance for optimizing pipeline performanceBe cognizant of streaming vs blocking stages orderingAvoid unwinding and regrouping documents just to process each array's elementsEncourage match filters to appear early in the pipelineSummary
Chapter 4: Harnessing the Power of Expressions
Aggregation expressions explainedWhat do expressions produce?Chaining operator expressions togetherCan all stages use expressions?What is using $expr inside $match all about?Restrictions when using expressions within $matchAdvanced use of expressions for array processingif-else conditional comparisonThe power array operatorsfor-each looping to transform an arrayfor-each looping to compute a summary value from an arrayfor-each looping to locate an array elementReproducing $map behavior using $reduceAdding new fields to existing objects in an arrayRudimentary schema reflection using arraysSummary
Chapter 5: Optimizing Pipelines for Sharded Clusters
A brief summary of MongoDB sharded clustersSharding implications for pipelinesSharded aggregation constraintsWhere does a sharded aggregation run?Pipeline splitting at runtimeExecution of the split pipeline shardsExecution of the merger part of the split pipelineDifference in merging behavior for grouping versus sortingPerformance tips for sharded aggregationsSummary

Part 2: Aggregations by Example
Chapter 6: Foundational Examples: Filtering, Grouping, and Unwinding
Filtered top subsetScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultsPipeline observationsGroup and totalScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsUnpack arrays and group differentlyScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultsPipeline observationsDistinct list of valuesScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 7: Joining Data Examples
One-to-one joinScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsMulti-field join and one-to-manyScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 8: Fixing and Generating Data Examples
Strongly typed conversionScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsConverting incomplete date stringsScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsGenerating mock test dataScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 9: Trend Analysis Examples
Faceted classificationScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsLargest graph networkScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsIncremental analyticsScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 10: Securing Data Examples
Redacted viewScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsMask sensitive fieldsScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsRole programmatic restricted viewScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 11: Time-Series Examples
IoT power consumptionScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsState change boundariesScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 12: Array Manipulation Examples
Summarizing arrays for first, last, minimum, maximum, and average valuesScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsPivoting array items by a keyScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsArray sorting and percentilesScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsArray element groupingScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsArray fields joiningScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsComparison of two arraysScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsJagged array condensingScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Chapter 13: Full-Text Search Examples
What is Atlas Search?Compound text search criteriaScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsFacets and counts text searchScenarioPopulating the sample dataDefining the aggregation pipelineExecuting the aggregation pipelineExpected pipeline resultPipeline observationsSummary
Appendix
Create an Atlas Search index
Afterword
Index
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Content preview from Practical MongoDB Aggregations

7 Joining Data Examples

This chapter offers guidance on joining together data from two collections. Contrary to what you may have heard, MongoDB is quite capable of performing these joins. The method of data manipulation will differ depending on whether you're executing a one-to-one or one-to-many join. You will explore solutions for both scenarios.

This chapter will cover the following:

Implementing one-to-one joins
Implementing one-to-many joins
Dealing with multiple fields on each side of the join

One-to-one join

Sometimes, you need to join data between two collections, where one document in the first collection maps to one, and only one, document in the second collection. This section provides an example of performing this one-to-one join ...

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Practical MongoDB Aggregations

by Paul Done

7

Joining Data Examples

One-to-one join

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