What is a time stamp?
In the modern day, the usage of the word timestamp has expanded and is usually used in reference to the digital time and date that are attached to certain information related to any sort of digital data. So, the timestamp is basically a sequence of encoded information or characters that help in identifying the time of the occurrence of a certain event. A timestamp usually includes the date and time, but sometimes the timestamps are accurate so as to give the information about the millisecond too.
Hence, the computer records the current time of the occurrence of each event and the accuracy of the current time is maintained through mechanisms like Network Time Protocol (NTP) which calibrates the current time to minute fractions of a second. This precision makes it viable for applications and computers with networks to work and communicate effectively.
Uses of Timestamps
They have numerous uses. Some are mentioned below:
The mechanism of time stamp is mainly required for numerous synchronization purposes.
For example, in case of a multi-event transaction, timestamps are used to assign sequences so that in case of a failure, the transaction can be stopped.
Timestamps are also used for recording time in relation to particular starting points.
For example, in IP telephony the RTP or the real time protocol assigns timestamps in sequence to voice packets. This is turn enables the user to buffer, reassemble and deliver without any sort of error.
When programmers write programs, they are usually provided with an application program interface so that the operating systems can provide a timestamp for a program when it is being executed.
Timestamps are also required for tracking progress of different records over time. Accurate timestamps enable accurate comparisons.
The process in which actual data has timestamps recorded, is known as time-stamping.
What is UNIX time stamp?
Before we can start with what UNIX time is, it is essential to clarify what Unix Epoch is. Epoch is a term used in the field of chronology and is defined as an instant in time, which is chosen as the origin of a given particular era. So the UNIX epoch is January 1st 1970. Now the UNIX time stamp is a way in which time is tracked as a running total of seconds and this count has it's beginning from the UNIX epoch i.e. January, the first of 1970. So, the UNIX timestamp is the number of seconds between a date that we need to look up or mark and the UNIX epoch. This method of time stamping is very essential for computer systems to sort and date the information which is present in distributed and dynamic applications both online as well as on the client's side.
There are many timestamp formats that are commonly used. Log analysis by certain IT companies is capable of annotating a huge number of these timestamp formats. Time stamp annotations are also called date-time annotations and are constructed using two base formats-
A date format
A time format
The date-time annotations work in the following manner-
The date patterns are identified by an annotator in a text and are then annotated with date annotations.
The same process is repeated with time annotation by another annotator.
Finally, specific patterns in date and time are identified by the timestamp annotator in which the occurrence of date and time annotation contiguously is found in text.
The various time stamp formats are-
Binary format - 101100100000010111100001111100011011
Octal format - 13102714657
Hexadecimal formats - 590b99af
Hexatrigesimal format - opg5nz
Barcode format - the ones we see on the labels behind different products.
Human readable date can be converted to timestamps of various formats too.
The various types of timestamp formats can also be converted to human readable date.
The year 2038 problem
We know that the UNIX epoch is January 1st 1970, which is the point from which the Unix time stamps are calculated. However, on January 19th 2038, the Unix time stamp will stop working. This will happen due to a 32 bit overflow. Hence, before this moment two things can happen-
One, millions and millions of application will either need to find and adopt a new convention for time stamps.
Two, they migrate to 64 bit systems. This can buy a little more time before the time stamp expires.
Limitations of time stamps
One major limitation as we already discussed is the 2038 problem.
Secondly, timestamp values are stored as epoch seconds and hence the timestamp value of 1970-01-01-00:00:00 is reserved as the second #0 and represents 0000-00-00 00:00:00
Thirdly, previously there could be only one timestamp column per table in Maria DB 5.5 and this had the current timestamp defined as default value. This limit, however, does not apply anymore to MariaDB 10.0.
Disadvantages and advantages of Time stamps in SQL servers-
Timestamp as Datetime - The data type of a timestamp is merely an incrementing number and it actually doesn't preserve the date or time. A datetime data type is to be used in order to record a date and a time.
Timestamp as data base timestamp- there is a counter for each database that increments for each update operation or insert, which is performed on a table containing a timestamp column in the database. This is the database timestamp. This does not track the actual time but the relative time.
Timestamp as primary key- a timestamp column should not be considered as a primary key owing to the fact that the value is changing. Whenever an update is made to the row, the timestamp value changes.
Timestamp can be used as value changes identification.
Timestamps can be duplicated. However, Microsoft would definitely not recommend using the timestamp that way.
There are much more that we can talk about. The basic idea is that timestamp can be really useful but there are situations when it would be best to consider date and time instead of timestamp.