23 lines
1.2 KiB
Markdown
23 lines
1.2 KiB
Markdown
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+++
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noatcards = True
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isdraft = False
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+++
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# Database
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[ ](https://camo.githubusercontent.com/15a7553727e6da98d0de5e9ca3792f6d2b5e92d4/687474703a2f2f692e696d6775722e636f6d2f586b6d3543587a2e706e67)
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_[Source: Scaling up to your first 10 million users](https://www.youtube.com/watch?v=vg5onp8TU6Q) _
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### Relational database management system (RDBMS)
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A relational database like SQL is a collection of data items organized in tables.
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ACID is a set of properties of relational database [transactions](https://en.wikipedia.org/wiki/Database_transaction) .
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- Atomicity - Each transaction is all or nothing
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- Consistency - Any tranaction will bring the database from one valid state to another
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- Isolation - Excuting transactions concurrently has the same results as if the transactions were executed serially
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- Durability - Once a transaction has been committed, it will remain so
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There are many techniques to scale a relational database: master-slave replication, master-master replication, federation, sharding, denormalization, and SQL tuning.
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