Aggregation Pipeline
Aggregation, pipeline, EK, ARRAY, OF, STAGES, hai — HAR, STAGE, DOCUMENTS, ko, TRANSFORM, karta hai, aur, RESULT, AGLE, STAGE, ko, PASS, karta hai. $match, $group, $sort, $project, JAISE, STAGES, COMBINE, kiye, ja, sakte, HAIN.
Simple, find() QUERIES, se, KAAFI, ZYAADA, POWERFUL, hai — COMPLEX, DATA, TRANSFORMATIONS, GROUPING, aur, ANALYTICS, ke, liye, USE, hota hai (jaise, SQL, ke, GROUP BY, aur, JOIN, ka, COMBINATION).
db.orders.aggregate([
{ $match: { status: "completed" } }, // stage 1: filter
{ $group: { // stage 2: group + sum
_id: "$customerId",
totalSpent: { $sum: "$amount" }
}},
{ $sort: { totalSpent: -1 } }, // stage 3: sort
{ $limit: 10 } // stage 4: top 10
]);- Aggregation pipeline = stages ka array, HAR, stage, documents, transform, karta hai
- $match, $group, $sort, $project = common, stages
- find() se, zyaada, powerful — complex, transformations/analytics, ke, liye
$project, stage, se, output, documents, ki, SHAPE, control, ki, ja, sakti, hai — sirf, fields, select, karne, ke, ALAWA, NAYE, computed, fields, bhi, banaye, ja, sakte, hain (jaise, fullName, first, aur, last, name, combine, karke).
{ $project: {
fullName: { $concat: ["$firstName", " ", "$lastName"] },
email: 1
}}$addFields, EXISTING, fields, ko, RAKHTE, hue, NAYE, fields, ADD, karta hai. $project, sirf, EXPLICITLY, specified, fields, hi, RAKHTA, hai — agar, TUMHE, sirf, EK, field, ADD, karni, hai, baaki, sab, waise, hi, rakhni, hai, $addFields, SIMPLER, hai.