[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"me":3,"catalog:en:database\u002Fmongodb":4,"config":214},null,{"field_key":5,"field_name":6,"seniority":7,"topic_key":7,"topic_name":7,"spec_key":8,"spec_name":9,"locale":10,"cell_total":11,"field_total":12,"seniorities":13,"topics":17,"specs":118,"samples":129},"database","Database","","mongodb","MongoDB","en",450,2475,[14,15,16],"junior","mid","senior",[18,22,25,28,31,34,37,40,43,46,49,52,55,58,61,64,67,70,73,76,79,82,85,88,91,94,97,100,103,106,109,112,115],{"key":19,"name":20,"count":21},"backup-recovery","Backup Recovery",75,{"key":23,"name":24,"count":21},"data-modeling","Data Modeling",{"key":26,"name":27,"count":21},"indexing","Indexing",{"key":29,"name":30,"count":21},"mongodb-aggregation","Mongodb Aggregation",{"key":32,"name":33,"count":21},"mongodb-indexes-queries","Mongodb Indexes Queries",{"key":35,"name":36,"count":21},"mongodb-operations","Mongodb Operations",{"key":38,"name":39,"count":21},"mongodb-replication-sharding","Mongodb Replication Sharding",{"key":41,"name":42,"count":21},"mongodb-schema-modeling","Mongodb Schema Modeling",{"key":44,"name":45,"count":21},"mongodb-transactions-consistency","Mongodb Transactions Consistency",{"key":47,"name":48,"count":21},"mysql-indexes","Mysql Indexes",{"key":50,"name":51,"count":21},"mysql-innodb-transactions","Mysql Innodb Transactions",{"key":53,"name":54,"count":21},"mysql-operations","Mysql Operations",{"key":56,"name":57,"count":21},"mysql-query-optimization","Mysql Query Optimization",{"key":59,"name":60,"count":21},"mysql-replication-scaling","Mysql Replication Scaling",{"key":62,"name":63,"count":21},"mysql-types-constraints","Mysql Types Constraints",{"key":65,"name":66,"count":21},"nosql-models","Nosql Models",{"key":68,"name":69,"count":21},"performance-tuning","Performance Tuning",{"key":71,"name":72,"count":21},"pg-indexes","Pg Indexes",{"key":74,"name":75,"count":21},"pg-mvcc-vacuum","Pg Mvcc Vacuum",{"key":77,"name":78,"count":21},"pg-operations","Pg Operations",{"key":80,"name":81,"count":21},"pg-query-planning","Pg Query Planning",{"key":83,"name":84,"count":21},"pg-transactions-locking","Pg Transactions Locking",{"key":86,"name":87,"count":21},"pg-types-constraints","Pg Types Constraints",{"key":89,"name":90,"count":21},"query-optimization","Query Optimization",{"key":92,"name":93,"count":21},"redis-cluster-sharding","Redis Cluster Sharding",{"key":95,"name":96,"count":21},"redis-data-structures","Redis Data Structures",{"key":98,"name":99,"count":21},"redis-expiration-eviction","Redis Expiration Eviction",{"key":101,"name":102,"count":21},"redis-persistence","Redis Persistence",{"key":104,"name":105,"count":21},"redis-replication-sentinel","Redis Replication Sentinel",{"key":107,"name":108,"count":21},"redis-transactions-scripting","Redis Transactions Scripting",{"key":110,"name":111,"count":21},"replication-scaling","Replication Scaling",{"key":113,"name":114,"count":21},"security-access","Security Access",{"key":116,"name":117,"count":21},"transactions-isolation","Transactions Isolation",[119,120,123,126],{"key":8,"name":9,"count":11},{"key":121,"name":122,"count":11},"mysql","MySQL",{"key":124,"name":125,"count":11},"postgresql","PostgreSQL",{"key":127,"name":128,"count":11},"redis","Redis",[130,148,161,175,188,201],{"id":131,"topic":30,"difficulty":132,"body":133,"options":134,"correct_key":139,"explanation":147},"019f87c2-bcd1-7940-b05c-61d3ddd80dd0",1,"In MongoDB, what is an aggregation pipeline?",[135,138,141,144],{"key":136,"text":137},"a","A single query operator that replaces `find()` entirely",{"key":139,"text":140},"b","An ordered sequence of stages, where each stage's output feeds the next stage's input",{"key":142,"text":143},"c","A background thread that pre-computes indexes for faster reads",{"key":145,"text":146},"d","A stored procedure written in JavaScript and executed on the client","An aggregation pipeline is an array of stages (e.g. `$match`, `$group`, `$project`) passed to `aggregate()`; documents flow through the stages in order, each stage transforming the output of the previous one. It doesn't replace `find()` (a) — `find()` still exists for simple queries — it isn't an index-building thread (c), and it isn't a stored procedure (d).",{"id":149,"topic":30,"difficulty":132,"body":150,"options":151,"correct_key":136,"explanation":160},"019f87c2-bcd5-742d-a71f-97886173c475","What does the `$match` stage do in an aggregation pipeline?",[152,154,156,158],{"key":136,"text":153},"Filters documents so only those matching the given condition pass to the next stage",{"key":139,"text":155},"Renames every field in the document to the given target name",{"key":142,"text":157},"Joins the current collection with another collection by a shared field",{"key":145,"text":159},"Groups documents by a key and computes an accumulator per group","`$match` filters the input documents using query-like criteria, letting only matching documents continue down the pipeline — conceptually similar to a `WHERE` clause or `find()`'s query argument. Renaming fields is `$project`\u002F`$addFields` (b), joining is `$lookup` (c), and grouping is `$group` (d).",{"id":162,"topic":30,"difficulty":163,"body":164,"options":165,"correct_key":142,"explanation":174},"019f87c2-bcd5-7ea8-bae7-0ba61faa5ce6",2,"```js\ndb.orders.aggregate([\n  { $group: { _id: \"$status\", total: { $sum: \"$amount\" } } }\n])\n```\nWhat does the `_id` field inside `$group` control?",[166,168,170,172],{"key":136,"text":167},"It is optional metadata and can be omitted from a `$group` stage",{"key":139,"text":169},"It always refers to the original MongoDB `_id` field of each document",{"key":142,"text":171},"It defines the grouping key — here, one output document per distinct `status` value",{"key":145,"text":173},"It sets the name of the output collection where grouped results are stored","`$group`'s `_id` expression is mandatory and defines what documents are grouped by — here `\"$status\"` means one result document per distinct status, each carrying the computed `total`. It is required, not optional (a); it does not have to reference the document's original `_id` (b), and `$group` doesn't write to a collection by itself — that's `$out`\u002F`$merge` (d).",{"id":176,"topic":30,"difficulty":132,"body":177,"options":178,"correct_key":145,"explanation":187},"019f87c2-bcd7-7c38-9d8c-d9cf23fe53a6","What is the primary purpose of the `$project` stage?",[179,181,183,185],{"key":136,"text":180},"To permanently delete unwanted fields from the underlying collection on disk",{"key":139,"text":182},"To create a new index on the fields listed in the stage",{"key":142,"text":184},"To filter out documents that don't satisfy a boolean condition",{"key":145,"text":186},"To reshape documents — include, exclude, or compute fields for the output","`$project` reshapes each document: it can include existing fields, exclude them, rename them, or compute new fields from expressions — purely for the output of the pipeline. It never modifies the stored collection on disk (a), it doesn't create indexes (b, that's `createIndex`), and filtering documents is `$match`'s job (c).",{"id":189,"topic":30,"difficulty":163,"body":190,"options":191,"correct_key":139,"explanation":200},"019f87c2-bcd9-767f-9d49-3d680378a5c8","```js\n{ $group: { _id: \"$customerId\", orderCount: { $sum: 1 } } }\n```\nWhat does `{ $sum: 1 }` compute here?",[192,194,196,198],{"key":136,"text":193},"The sum of every numeric field found anywhere in the document",{"key":139,"text":195},"A count of documents in each group, since `1` is added once per document",{"key":142,"text":197},"The average order amount for each customer, expressed as an integer",{"key":145,"text":199},"The highest `_id` value observed among the grouped customer documents","`{ $sum: 1 }` adds the literal value `1` for every document that falls into a group, which is the standard idiom for counting documents per group — equivalent to `COUNT(*) ... GROUP BY`. It does not sum arbitrary numeric fields (a), it isn't an average (c, that's `$avg`), and it has nothing to do with `_id` magnitude (d).",{"id":202,"topic":30,"difficulty":132,"body":203,"options":204,"correct_key":136,"explanation":213},"019f87c2-bcda-715b-acf3-6e59b8911c47","What does the `$unwind` stage do to a document that has an array field?",[205,207,209,211],{"key":136,"text":206},"It deconstructs the array, outputting one document per array element",{"key":139,"text":208},"It sorts the array's elements in ascending order in place",{"key":142,"text":210},"It removes the array field entirely from every document",{"key":145,"text":212},"It merges the array into a single comma-separated string field","`$unwind` takes a document with an array field and outputs a separate document for each element of that array, with the field replaced by the single element value — useful before grouping or filtering on array contents. It doesn't sort in place (b), doesn't delete the field (c), and doesn't stringify the array (d).",{"fields":215,"seniorities":391,"interview_shapes":392,"locales":397,"oauth":399,"question_count":402,"coach_enabled":403,"jd_match_enabled":403},[216,241,261,278,302,315,324,343,365,372,378,385],{"key":217,"name_tr":218,"name_en":218,"sort":132,"specializations":219},"backend","Backend",[220,223,226,229,232,235,238],{"key":221,"name":222,"field":217},"general","Genel",{"key":224,"name":225,"field":217},"go","Go",{"key":227,"name":228,"field":217},"python","Python",{"key":230,"name":231,"field":217},"java","Java",{"key":233,"name":234,"field":217},"csharp","C#\u002F.NET",{"key":236,"name":237,"field":217},"nodejs","Node.js",{"key":239,"name":240,"field":217},"php","PHP",{"key":242,"name_tr":243,"name_en":243,"sort":163,"specializations":244},"frontend","Frontend",[245,246,249,252,255,258],{"key":221,"name":222,"field":242},{"key":247,"name":248,"field":242},"javascript","JavaScript",{"key":250,"name":251,"field":242},"typescript","TypeScript",{"key":253,"name":254,"field":242},"react","React",{"key":256,"name":257,"field":242},"vue","Vue",{"key":259,"name":260,"field":242},"angular","Angular",{"key":262,"name_tr":263,"name_en":263,"sort":264,"specializations":265},"fullstack","Fullstack",3,[266,267,268,269,270,271,272,273,274,275,276,277],{"key":221,"name":222,"field":262},{"key":224,"name":225,"field":217},{"key":227,"name":228,"field":217},{"key":230,"name":231,"field":217},{"key":233,"name":234,"field":217},{"key":236,"name":237,"field":217},{"key":239,"name":240,"field":217},{"key":247,"name":248,"field":242},{"key":250,"name":251,"field":242},{"key":253,"name":254,"field":242},{"key":256,"name":257,"field":242},{"key":259,"name":260,"field":242},{"key":279,"name_tr":280,"name_en":280,"sort":281,"specializations":282},"devops-cloud","DevOps \u002F Cloud",4,[283,284,287,290,293,296,299],{"key":221,"name":222,"field":279},{"key":285,"name":286,"field":279},"aws","AWS",{"key":288,"name":289,"field":279},"gcp","GCP",{"key":291,"name":292,"field":279},"azure","Azure",{"key":294,"name":295,"field":279},"kubernetes","Kubernetes",{"key":297,"name":298,"field":279},"terraform","Terraform",{"key":300,"name":301,"field":279},"linux","Linux",{"key":303,"name_tr":304,"name_en":304,"sort":305,"specializations":306},"ai-engineer","AI Engineer",5,[307,308,309,312],{"key":221,"name":222,"field":303},{"key":227,"name":228,"field":303},{"key":310,"name":311,"field":303},"llm-rag","LLM\u002FRAG",{"key":313,"name":314,"field":303},"mlops","MLOps",{"key":5,"name_tr":316,"name_en":6,"sort":317,"specializations":318},"Veritabanı",6,[319,320,321,322,323],{"key":221,"name":222,"field":5},{"key":124,"name":125,"field":5},{"key":121,"name":122,"field":5},{"key":8,"name":9,"field":5},{"key":127,"name":128,"field":5},{"key":325,"name_tr":326,"name_en":327,"sort":328,"specializations":329},"mobile","Mobil","Mobile",7,[330,331,334,337,340],{"key":221,"name":222,"field":325},{"key":332,"name":333,"field":325},"ios-swift","iOS (Swift)",{"key":335,"name":336,"field":325},"android-kotlin","Android (Kotlin)",{"key":338,"name":339,"field":325},"flutter","Flutter",{"key":341,"name":342,"field":325},"react-native","React Native",{"key":344,"name_tr":345,"name_en":346,"sort":347,"specializations":348},"security","Güvenlik","Security",8,[349,350,353,356,359,362],{"key":221,"name":222,"field":344},{"key":351,"name":352,"field":344},"appsec","AppSec",{"key":354,"name":355,"field":344},"offensive-pentest","Offensive \u002F Pentest",{"key":357,"name":358,"field":344},"cloud-security","Cloud Security",{"key":360,"name":361,"field":344},"devsecops","DevSecOps",{"key":363,"name":364,"field":344},"blue-team-incident","Blue Team \u002F Incident",{"key":366,"name_tr":367,"name_en":368,"sort":369,"specializations":370},"qa-test-automation","QA \u002F Test Otomasyonu","QA \u002F Test Automation",9,[371],{"key":221,"name":222,"field":366},{"key":373,"name_tr":374,"name_en":374,"sort":375,"specializations":376},"data-engineer","Data Engineer",10,[377],{"key":221,"name":222,"field":373},{"key":379,"name_tr":380,"name_en":381,"sort":382,"specializations":383},"game-dev","Oyun Geliştirme","Game Development",11,[384],{"key":221,"name":222,"field":379},{"key":386,"name_tr":387,"name_en":387,"sort":388,"specializations":389},"ml-engineer","ML Engineer",12,[390],{"key":221,"name":222,"field":386},[14,15,16],{"junior":393,"mid":395,"senior":396},{"questions":394,"median_sec":3},20,{"questions":394,"median_sec":3},{"questions":394,"median_sec":3},[398,10],"tr",[400,401],"google","github",21750,true]