Compound Indexes
Compound, index, MULTIPLE, FIELDS, ko, EK, SAATH, INDEX, karta hai — FIELD, ORDER, MATTER, karta hai. "ESR" (Equality, Sort, Range) RULE, EK, GOOD, GUIDELINE, hai, FIELD, ORDER, DECIDE, karne, ke, liye.
"Prefix" RULE — EK, COMPOUND, INDEX, {a: 1, b: 1, c: 1}, QUERIES, ko, SUPPORT, karta hai, JO, {a}, {a, b}, YA, {a, b, c}, PAR, FILTER/SORT, karti, hain — LEKIN, {b}, ya, {c}, ALONE, PAR, NAHI (INDEX, USE, NAHI, HOGA).
// Compound index — status PEHLE, phir, createdAt:
db.orders.createIndex({ status: 1, createdAt: -1 });
// Ye query, index, USE, karti hai:
db.orders.find({ status: "completed" }).sort({ createdAt: -1 });
// Ye query, index, USE, NAHI, karegi (prefix rule violate):
db.orders.find({ createdAt: { $gt: someDate } });- Compound index = multiple fields, ek, saath, — field, ORDER, matter, karta, hai
- "Prefix rule" — index, ke, LEFTMOST, fields, ke, queries, hi, index, use, kar, sakti, hain
- ESR (Equality-Sort-Range) rule, field, order, decide, karne, mein, HELP, karta hai
MongoDB, KABHI-KABHI, MULTIPLE, single-field, indexes, ko, "intersect" kar, sakta hai, EK, query, ke, liye — LEKIN, YE, generally, EK, WELL-DESIGNED, compound, index, se, KAM, EFFICIENT, hai. Query, patterns, ke, hisaab, se, compound, indexes, PLAN, karna, BEHTAR, hai.
Agar, EK, query, ke, saare, fields, (filter, sort, aur, projection, mein) EK, index, mein, HI, present, hain, MongoDB, ko, ACTUAL, document, fetch, karne, ki, ZAROORAT, nahi, PADТI — YE, EK, "covered, query" hai aur, extremely, FAST, hai.
db.users.createIndex({ email: 1, name: 1 });
// Covered query — sirf, index, se, hi, answer, mil, jaata, hai:
db.users.find({ email: "a@b.com" }, { name: 1, _id: 0 });