This reading introduces why single-user database assumptions break down in real-world multi-user environments, explaining the challenges that arise when many transactions execute simultaneously, and serves as a conceptual foundation for the rest of the module.
Topics
This module covers 7 topics. Open a topic to see its subtopics.
Module Content
16 items.
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This reading explains what a database transaction is, defines the four ACID properties (Atomicity, Consistency, Isolation, Durability), and illustrates how they protect data integrity across multi-step operations such as bank transfers or order placement, giving learners a framework for evaluating database reliability.
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This reading identifies and explains the classic concurrency problems—dirty reads, lost updates, non-repeatable reads, and phantom reads—that occur when transactions interfere with one another, helping learners recognize the specific failure modes they must design against.
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This reading covers how relational database engines use shared and exclusive locks to serialize access to shared data, explaining lock types, lock granularity, and how locking enforces transaction isolation, so learners understand the primary mechanism behind concurrency control.
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This reading explains what deadlocks are, why they occur when transactions compete for shared resources, and how database systems detect and resolve them, equipping learners to anticipate, prevent, and handle deadlock scenarios in their designs.
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This reading describes the standard SQL transaction isolation levels—Read Uncommitted, Read Committed, Repeatable Read, and Serializable—explaining what concurrency anomalies each level permits or prevents, so learners can choose the appropriate level for a given application's consistency and performance requirements.
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This reading surveys practical concurrency control strategies and design best practices—such as optimistic versus pessimistic locking and transaction scope management—giving learners actionable guidance for building database-backed systems that are both correct and performant under concurrent load.
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This reading surveys practical concurrency control strategies and design best practices—such as optimistic versus pessimistic locking and transaction scope management—giving learners actionable guidance for building database-backed systems that are both correct and performant under concurrent load.
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A reading that introduces multi-user database environments, using examples like web storefronts and campus registration systems to show why simultaneous access creates design challenges learners must plan for.
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A lesson defining database transactions and the ACID properties (atomicity, consistency, isolation, durability) through examples such as funds transfers, giving learners the vocabulary for reasoning about safe units of work.
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A reading that explains how interleaved reads and writes cause classic concurrency problems — dirty reads, lost updates, non-repeatable reads, and phantoms — so learners can recognize data conflicts in real systems.
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A lesson on locking as a concurrency mechanism, covering shared (read) versus exclusive (write) locks, lock granularity, and how databases arbitrate who may access data and when.
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A reading on deadlocks, showing how circular lock waits form between transactions and describing detection, timeout, victim selection, and prevention techniques for resolving them.
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A lesson on the four SQL isolation levels — Read Uncommitted, Read Committed, Repeatable Read, and Serializable — and the trade-off between the anomalies each permits and the performance each costs.
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A reading comparing pessimistic, optimistic, and multiversion concurrency control strategies, with best practices for choosing an approach and designing applications that scale under contention.
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A consolidated module page compiling all lessons on multi-user environments, transactions and ACID, concurrency problems, locking, deadlocks, isolation levels, and control strategies for single-sitting review or printing.