What are phantom reads in SQL?

Can you explain what phantom reads are in SQL?

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 that 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 changes to the set of rows returned by a query.

What isolation level can prevent phantom reads?

To prevent phantom reads, you can use the Serializable isolation level. This level ensures that no other transactions can insert or delete rows that would affect the results of your transaction.

Are there any performance implications of using Serializable isolation?

Yes, using Serializable isolation can lead to decreased performance due to increased locking and potential contention between transactions. It's important to balance data integrity with performance needs.