databases/
Tables, queries, indexes, transactions, storage engines and caching.
4 results
databases/transactions-why-a-money-transfer-must-save-both-changes-or-neither.md
Transactions: why a money transfer must save both changes or neither
Sending £50 between two accounts takes two changes to a database. If the power fails between them, the money vanishes. A transaction groups…
databases/sql-indexes-why-finding-one-row-among-200-000-takes-about-18-steps.md
SQL indexes: why finding one row among 200,000 takes about 18 steps
A database with 200,000 customers can answer "find this email" by reading every row, or by reading about 18 entries. The difference is an…
databases/database-transactions-why-moving-money-is-all-or-nothing.md
Database transactions: why moving money is all or nothing
Paying someone is really two changes in a database: take money from one account, add it to another. If the power dies between them, money…
databases/what-is-a-database-index-find-one-row-without-reading-them-all.md
What is a database index? Find one row without reading them all
Ask a database for one person among a million rows and it could read every row until it finds them. That is slow. An index is the…