What are phantom reads?

Can you explain what phantom reads are in database transactions?

Sure! Phantom reads occur when a transaction reads a set of rows that match a certain condition, but another transaction inserts or deletes rows that affect the result set before the first transaction is completed.

How do phantom reads differ from dirty reads and non-repeatable reads?

Great question! Dirty reads allow a transaction to read uncommitted changes from another transaction, while non-repeatable reads occur when a row is changed by another transaction after it has been read. Phantom reads specifically involve new rows being added or existing rows being removed.

What isolation level can prevent phantom reads?

To prevent phantom reads, you can use the Serializable isolation level, which ensures that transactions are completely isolated from one another.

Are there any performance trade-offs with using Serializable isolation?

Yes, using Serializable isolation can lead to decreased performance due to increased locking and potential for deadlocks, as it restricts concurrent access to data.