Define serializability in database transaction management, what is serializability, serializable schedules, when would we say that a schedule is serializable
Serializablity
As we know, we cannot execute all
transactions only in serial order as it will consume enormous amount of time
and resources. Hence, an RDBMS need to permit concurrent transactions
(transactions that are executed simultaneously).
Execution of a collection of multiple
transactions together is called as schedule. And, a schedule either should be serial
or serializable.
To ensure database consistency, a
database system must control execution of concurrent transactions. In other
words, the system must identify whether a schedule produces consistent database
or not.
How do we check whether a schedule
produces consistent database or not?
A schedule of concurrent
transactions ends in a consistent database if the schedule is equivalent to
some serial schedule.
If a schedule of concurrent
transactions can be converted into an equivalent serial schedule, then we say
that the schedule is serializable schedule. And this property is called
serializability.
The concept of serializability of
schedules is used to identify which schedules are correct when transaction
executions have interleaving of their operations in the schedules. There are
different notions of schedule equivalences. The following are two of the
important equivalence of schedules;
- View serializability
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