MongoDB Database

6.

The Aggregation Framework

6.1.

Introduction to Data Aggregation

6.1.1.

Aggregation vs Simple Queries

6.1.2.

Aggregation vs MapReduce

6.1.3.

Use Cases for Aggregation

6.1.4.

Performance Characteristics

6.2.

The Aggregation Pipeline

6.2.1.

Pipeline Concept and Architecture

6.2.2.

Stage-by-Stage Processing

6.2.3.

Document Flow Through Pipeline

6.2.4.

Pipeline Syntax and Structure

6.2.5.

Pipeline Optimization

6.3.

Common Pipeline Stages

6.3.1.

6.3.1.1.

Document Filtering

6.3.1.2.

Query Operator Usage

6.3.1.3.

Early Filtering Benefits

6.3.2.

6.3.2.1.

Field Selection and Exclusion

6.3.2.2.

Field Transformation

6.3.2.3.

Computed Fields

6.3.2.4.

Nested Field Handling

6.3.3.

6.3.3.1.

Grouping Documents by Fields

6.3.3.2.

Accumulator Expressions

6.3.3.3.

Group Key Specifications

6.3.3.4.

Memory Usage Considerations

6.3.4.

6.3.4.1.

Document Ordering

6.3.4.2.

Sort Key Specifications

6.3.4.3.

Index Usage in Sorting

6.3.4.4.

Memory Limitations

6.3.5.

6.3.5.1.

Result Set Limitation

6.3.5.2.

Pagination Strategies

6.3.5.3.

Performance Optimization

6.3.6.

6.3.6.1.

Document Skipping

6.3.6.2.

Pagination Implementation

6.3.6.3.

Offset Considerations

6.3.7.

6.3.7.1.

Array Deconstruction

6.3.7.2.

Preserving Empty Arrays

6.3.7.3.

Index Preservation

6.3.8.

6.3.8.1.

Left Outer Join Operations

6.3.8.2.

Cross-Collection References

6.3.8.3.

Pipeline-Based Lookups

6.3.8.4.

Performance Considerations

6.3.9.

6.3.9.1.

Writing Results to Collections

6.3.9.2.

Collection Replacement Behavior

6.3.9.3.

Atomicity Guarantees

6.3.10.

6.3.10.1.

Flexible Output Options

6.3.10.2.

Upsert and Update Behaviors

6.3.10.3.

Target Collection Handling

6.4.

Advanced Pipeline Stages

6.4.1.

$addFields Stage

6.4.2.

$replaceRoot Stage

6.4.3.

6.4.4.

6.4.5.

$bucketAuto Stage

6.4.6.

6.4.7.

6.5.

Aggregation Expressions and Accumulators

6.5.1.

Arithmetic Expressions

6.5.2.

String Expressions

6.5.3.

Date Expressions

6.5.4.

Conditional Expressions

6.5.5.

Array Expressions

6.5.6.

Accumulator Operators

6.5.6.1.

6.5.6.2.

6.5.6.3.

6.5.6.4.

6.5.6.5.

6.5.6.6.

6.5.6.7.

6.5.6.8.

6.5.6.9.

6.5.6.10.

6.6.

Building and Optimizing Aggregation Pipelines

6.6.1.

Pipeline Design Principles

6.6.2.

Stage Order Optimization

6.6.3.

Index Usage in Aggregation

6.6.4.

Memory Management

6.6.5.

Handling Large Data Sets

6.6.6.

Pipeline Performance Tuning

6.6.7.

Aggregation Explain Plans

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7. Transactions