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Enforcing the Thomas write rule only requires checking to see if the write timestamp of the object is greater than the time stamp of the transaction performing a write. If so, the write is discarded In the example above, if we call TS(T) the timestamp of transaction T, and WTS(O) the write timestamp of object O, then T2's write sets WTS(C) to ...
Many computer systems measure time and date using Unix time, an international standard for digital timekeeping. Unix time is defined as the number of seconds elapsed since 00:00:00 UTC on 1 January 1970 (an arbitrarily chosen time based on the creation of the first Unix system), which has been dubbed the Unix epoch. [6]
Note (9): Despite the lack of a date datatype, SQLite does include date and time functions, [83] which work for timestamps between 24 November 4714 B.C. and 1 November 5352. Note (10): Informix DATETIME type has adjustable range from YEAR only through 1/10000th second.
In this case, if the transaction's timestamp is after the object's read timestamp, the read timestamp is set to the transaction's timestamp. If a transaction wants to write to an object, 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 ...
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second. Timestamps do not have to be based on some absolute notion of time, however.
Reference Timestamp: 64 bits Time when the system clock was last set or corrected, in NTP timestamp format. Origin Timestamp (org): 64 bits Time at the client when the request departed, in NTP timestamp format. Receive Timestamp (rec): 64 bits Time at the server when the request arrived, in NTP timestamp format. Transmit Timestamp (xmt): 64 bits
Time::HiRes::time [41] 1 μs PHP: time() mktime() 1 s 1 January 1970 microtime() 1 μs PureBasic: Date() 1 s 1 January 1970 to 19 January 2038 Python: datetime.now().timestamp() 1 μs (*) 1 January 1970 RPG: CURRENT(DATE), %DATE CURRENT(TIME), %TIME: 1 s 1 January 0001 to 31 December 9999 CURRENT(TIMESTAMP), %TIMESTAMP: 1 μs Ruby: Time.now ...