In database transactions theory, what is the difference between a strict schedule and a schedule that is merely secured against cascade aborts? Could you give an example of a schedule that is secured against cascade aborts but is not strict?I found these slides that give definitions but it's still not clear to me where is the difference (they just seem differently worded).
What is the difference between strict schedule and cascadeless schedule?
database theory
On a cascadeless schedule a transaction $T_2$ cannot read a value $a$ if a transaction $T_1$ wrote $a$ before that and didn't commit. On a strict schedule $T_2$ also wouldn't be able to write $a$ after $T_1$ wrote it (even if it read $a$ before $T_1$ wrote it).If you read carefully, the definition of strict says not read or overwritten. That's the difference.I reproduce here an example of cascadeless but not strict schedule, from the Wikipedia page on the subject: