Database Management Systems · Transactions and concurrency

Concurrency anomalies

The specific bad things that can happen when two transactions run at the same time: dirty, non-repeatable, and phantom reads.

Also known as: dirty read, non-repeatable read, phantom read.

Start a lesson on Concurrency anomalies

Learn first

• Transactions and ACID properties: The four guarantees (atomicity, consistency, isolation, durability) that make a transaction feel like one indivisible unit.

Leads to

• Isolation levels: How much of those concurrency anomalies a database is willing to allow, chosen as a tradeoff against speed.
• Conflict-serializability: Checking whether an interleaved schedule of transactions could have happened in some one-at-a-time order instead.

Related topics

• Isolation levels: How much of those concurrency anomalies a database is willing to allow, chosen as a tradeoff against speed.
• Conflict-serializability: Checking whether an interleaved schedule of transactions could have happened in some one-at-a-time order instead.