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public/sql.md
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27 | 27 | ### [1] Why we (I) love relational databases |
28 | 28 | |
29 | 29 | * **ACID** |
30 | - * Atomicity (transactions [multiple operations can be "all or nothing"] - even with externalities such as power loss) |
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31 | - * Consistency (what's on disk is always acceptable as a state - including constraints, etc.) |
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32 | - * Isolation (no transaction affects another) |
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30 | + * Atomicity (if you cluster a number of operations as a "transaction," then they will all be executed or none will be executed - even with externalities such as power loss) |
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31 | + * Consistency (what's on disk is always acceptable - including constraints, etc. In other words, if you unplug the computer that has your database, the database stored on disk will work when the power is restored: The on-disk version will not be corrupted.) |
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32 | + * Isolation (no transaction affects another; so multiple users can all be running their separate transactions and they won't interfere with one another.) |
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33 | 33 | * Durability (if an insert completes, it is really written to disk) |
34 | 34 | * Do we need these? |
35 | 35 | * What apps don't need these things? |