خطوط التجميع (Aggregation Pipelines)

في هذا الدرس

compute summaries in the database.

الموضوعات المخطط لها

• A pipeline is a list of stages; each passes documents to the next: $match, $group, $sort, $project, $lookup.
• Put $match first so it can use an index and shrink the data.
• $group with $avg and $sum computes counts and averages.
• Do the work in the database instead of loading documents into Java.
• $lookup is a join; use sparingly, it is not a relational join engine.