Hello there, I’m studing from this book (Elmasri – Navathe, Fundamentals of Database Systems, 7th Ed), and I'm having problems understanding this definition:
A schedule S is recoverable if no transaction T in S commits until all transactions T′ that have written some item X that T reads have committed. A transaction T reads from transaction T′ in a schedule S if some item X is first written by T′ and later read by T. In addition, T′ should not have been aborted before T reads item X, and there should be no transactions that write X after T′ writes it and before T reads it (unless those transactions, if any, have aborted before T reads X).
Can someone please explain me the bold part of this definition? I mean, if T' aborts before T reads, what's the problem? Thanks!
