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The format can serialize PHP's primitive and compound types, and also properly serializes references. [1] The format was first introduced in PHP 4. [2] In addition to PHP, the format is also used by some third-party applications that are often integrated with PHP applications, for example by Lucene/Solr. [3]
For each transaction T x participating in schedule S, create a node labeled T i in the precedence graph. Thus the precedence graph contains T 1, T 2, T 3. For each case in S where T j executes a read_item(X) after T i executes a write_item(X), create an edge (T i → T j) in the precedence graph. This occurs nowhere in the above example, as ...
The following expressions illustrate the hierarchical (containment) relationships between serializability and recoverability classes: Serial ⊂ conflict-serializable ⊂ view-serializable ⊂ all schedules; Serial ⊂ strict ⊂ cascadeless (ACA) ⊂ recoverable ⊂ all schedules; The Venn diagram (below) illustrates the above clauses graphically.
For example, consider a database with 3 variables (A, B, C), and two atomic operations C := A (T1), and C := B (T2). Each transaction involves a read (A or B), and a write (C). The only conflict between these transactions is the write on C. The following is one possible schedule for the operations of these transactions:
^ PHP will unserialize any floating-point number correctly, but will serialize them to their full decimal expansion. For example, 3.14 will be serialized to 3.140 000 000 000 000 124 344 978 758 017 532 527 446 746 826 171 875. ^ XML data bindings and SOAP serialization tools provide type-safe XML serialization of programming data structures ...
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).
In databases, and transaction processing (transaction management), snapshot isolation is a guarantee that all reads made in a transaction will see a consistent snapshot of the database (in practice it reads the last committed values that existed at the time it started), and the transaction itself will successfully commit only if no updates it has made conflict with any concurrent updates made ...
Even if every local schedule of a single database is serializable, the global schedule of a whole system is not necessarily serializable. The massive communication exchanges of conflict information needed between databases to reach conflict serializability globally would lead to unacceptable performance, primarily due to computer and ...