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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 ...
^ 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 ...
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:
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).
However, some extensions which use the PHP extension framework do not expose an API to the PHP developer. The PDO MySQL driver extension, for example, does not expose an API to the PHP developer, but provides an interface to the PDO layer above it. MySQLi is an improved version of the older PHP MySQL driver, offering various benefits. [3]
but the transaction started before the object's read timestamp it means that something has had a look at the object, and we assume it took a copy of the object's data. So we can't write to the object as that would make any copied data invalid, so the transaction is aborted and must be restarted.