Backend & Data

The territory

30 core terms mapped for this field, ranked by how often builders reach for them. Each one is a future entry. Want to bust one? One entry, one file, one pull request.

• primary keycolumn or columns uniquely identifying each table row"the id column" · "what makes each row unique"
• foreign keycolumn referencing another table's row, enforcing relational integrity"this order belongs to that customer" · "linking two tables"
• indexprecomputed lookup structure making queries fast on chosen columns"why is my query slow on a big table" · "the thing that makes searching fast"
• schema migrationversioned, repeatable script that changes database structure safely"the file that adds a column without breaking prod" · "how do I change my database after launch"
• joinquery operation combining related rows from multiple tables"combine two tables in one query" · "pull the user's name alongside their orders"
• N+1 queryloop firing one query per row instead of one batched query"it hits the database once per item in the list" · "hundreds of tiny queries in my logs"
• database transactiongroup of writes that all succeed or all roll back"either both updates happen or neither" · "money left one account but never arrived"
• ORMlibrary mapping database rows to objects in your language"writing database stuff without SQL" · "the thing that turns tables into code objects"
• cachefast intermediate store holding results to avoid recomputation"remember the answer so we don't ask again" · "Redis in front of the database" · "caching layer"
• connection poolreusable set of open database connections shared across requests"too many connections error" · "why serverless kills my database"
• job queuelist of background tasks workers pull and process asynchronously"do the slow thing after the response" · "a to-do list my server works through"
• workerlong-running process consuming jobs off a queue"the background process that does the slow jobs" · "a second server that drains the queue"
• cron jobtask that runs automatically on a fixed time schedule"run this every night at 2am" · "scheduled script"
• idempotencyrepeating the same operation produces no additional effect"clicking submit twice shouldn't double-charge" · "safe to retry"
• race conditionoutcome depends on unpredictable ordering of concurrent operations"two people bought the last one at once" · "it breaks only under load"
• normalizationsplitting data into tables so each fact is stored once"stop copy-pasting the same data everywhere" · "one source of truth per field"
• denormalizationdeliberately duplicating data to make reads faster"store the count on the row so I don't count every time" · "copy it for speed"
• soft deletemarking rows deleted instead of removing them"hide it but keep it recoverable" · "trash can instead of shredder"
• cursor paginationpaging by pointer rather than offset, stable under inserts"load more without repeating or skipping items" · "paging that doesn't break when new rows arrive"
• audit logappend-only record of who changed what and when"history of every edit" · "who touched this record"
• row-level securitydatabase rules restricting which rows each user can see"users should only see their own data" · "multi-tenant data isolation"
• seed datastarter records loaded so a fresh database is usable"fake data to develop against" · "prefill the empty database"
• backfillone-time job populating a new field across existing rows"fill in the column I just added for old data" · "catch up historical records"
• point-in-time recovery (PITR)restoring the database to any past moment"rewind the database to yesterday" · "undo after someone dropped a table" · "backup and restore"
• full-text searchindexed search over natural language content with ranking"a real search bar over my content" · "search inside the text"
• object storagebucket-based store for files, cheap and infinitely scalable"where uploaded files live" · "S3-style file dumping ground"
• document databasedatabase of nested JSON-like records without fixed schema"store JSON documents instead of rows" · "MongoDB-style database" · "document store"
• vector databasestore optimized for similarity search over embeddings"search by meaning not keywords" · "where AI memory lives"
• event-driven architectureservices react to published events instead of direct calls"something happened, let other parts react" · "fire and forget notifications between services"
• data pipelinestaged flow extracting, transforming, loading data between systems"move data from A to B and clean it" · "nightly sync job" · "ETL job"

Deeper in the field

• unique constraint database rule preventing duplicate values in selected columns
• database constraint rule enforcing valid values and relationships within stored data
• one-to-many relationship one record relates to several records in another table
• many-to-many relationship records on both sides relate through a junction table
• upsert insert a row or update it when already present
• ACID guarantees governing reliable and consistent database transactions
• transaction isolation rules controlling what concurrent transactions can observe
• database lock temporary restriction preventing conflicting concurrent data changes
• optimistic locking version check prevents overwriting someone else's concurrent edit
• query plan / EXPLAIN database analysis showing how a query will execute
• database view named query exposed like a virtual table
• materialized view stored, refreshable result of an expensive query
• stored procedure logic saved and executed inside the database itself
• database trigger automatic action fired on insert, update, or delete
• write-ahead log (WAL) durability log recording changes before applying them
• message broker infrastructure routing asynchronous messages between producers and consumers
• dead letter queue holding pen for jobs that failed repeatedly
• stateless service server keeping no per-user memory between requests
• read replica copy of the database serving reads to reduce primary load
• replication lag delay before a replica reflects the primary's writes
• eventual consistency replicas converge to same state after a short delay
• sharding splitting one dataset horizontally across multiple databases
• change data capture (CDC) streaming database changes out as an event feed
• time-series database store optimized for timestamped metric data
• key-value store simplest database: fetch a blob by its key
• graph database store optimized for traversing relationships between entities
• data warehouse analytics-optimized store separate from production database
• columnar storage data laid out by column for fast analytical scans
• schema-on-read vs schema-on-write validate structure when reading versus when storing
• identifier strategy random unique identifiers versus sequential numeric keys