A schedule becomes '''unrecoverable''' if a transaction <math>T_i</math> reads and relies on changes from another transaction <math>T_j</math>, and then <math>T_i</math> commits and <math>T_j</math> aborts.
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====Cascadeless====
Also'''Cascadeless schedules''' (a.k.a, "Avoiding Cascading Aborts (ACA) schedules") are schedules which avoid cascading aborts by disallowing dirty reads. Avoids'''Cascading thataborts''' aoccur singlewhen one transaction's abort leadscauses another transaction to aabort seriesbecause ofit transactionread rollbacks.and Arelied strategyon the first transaction's changes to preventan cascadingobject. abortsA is'''dirty toread''' disallowoccurs when a transaction fromreads readingdata from uncommitted changeswrite fromin another transaction.<ref>{{Cite inweb the|date=2019-08-06 same|title=Cascadeless schedulein DBMS |url=https://www.geeksforgeeks.org/cascadeless-in-dbms/ |access-date=2023-11-29 |website=GeeksforGeeks |language=en-US}}</ref>
The following examples are the same as the ones in the discussion on recoverable:
