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Operations of transactions in a schedule can interleave (i.e., transactions can be executed concurrently), but time orders between operations in each transaction must remain unchanged. The schedule is in partial order when the operations of transactions in a schedule interleave (i.e., when the schedule is conflict-serializable but not serial).
Also, typically recoverable data (i.e., data under transactions' control, e.g., database data; not to be confused with the recoverability property of a schedule) are directly accessed by a single transactional data manager component (also referred to as a resource manager) that handles local sub-transactions (the distributed transaction's ...
A schedule is conflict-serializable if and only if its precedence graph of committed transactions is acyclic. The precedence graph for a schedule S contains: A node for each committed transaction in S; An arc from T i to T j if an action of T i precedes and conflicts with one of T j 's actions. That is the actions belong to different ...
In concurrency control of databases, transaction processing (transaction management), and other transactional distributed applications, global serializability (or modular serializability) is a property of a global schedule of transactions. A global schedule is the unified schedule of all the individual database (and other transactional object ...
The transaction-related mechanisms typically constrain the database data access operations' timing (transaction schedules) to certain orders characterized as the serializability and recoverability schedule properties. Constraining database access operation execution typically means reduced performance (measured by rates of execution), and thus ...
In databases and transaction processing, two-phase locking (2PL) is a pessimistic concurrency control method that guarantees conflict-serializability. [1] [2] It is also the name of the resulting set of database transaction schedules (histories).
A database transaction is a unit of work, typically encapsulating a number of operations over a database (e.g., reading a database object, writing, acquiring lock, etc.), an abstraction supported in database and also other systems. Each transaction has well defined boundaries in terms of which program/code executions are included in that ...
2 Recoverable schedule. 1 comment. 3 References. 1 comment. 4 DBMS. 1 comment. 5 Commitment ordering. 1 comment. Toggle the table of contents. Talk: Database ...