Prepare for the Leap Second
A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1. Please refer to https://en.wikipedia.org/wiki/Leap_second for more information.
From our immediate perspective, next leap second insert will be June 30th 2015 will be one second longer and “June 30, 2015 23:59:60″ will be a valid and correct time. This could cause some issues around various solutions and applications depending on the technologies being used.
The good news is Microsoft SQL Server databases have no risk but may expose minor application issues on data granularity and error handling based on how your application is designed. So it is always good idea to be aware on this upcoming event and to be prepared accordingly. Please refer to https://support.microsoft.com/en-us/kb/909614?utm_content=bufferf43f4&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer for Microsoft’s official response to the question “How the Windows Time service treats a leap second”.
However many other Operating Systems and RDBMS solutions are exposed to various degree of risks. For example, Java programs are at risk of generating endless error loops (which can cause issues like hung CPU etc) unless your system is patched before hand. This means Open source databases should be reviewed before June 30th 2015 and patches must be applied as deemed suitable.
Please refer to http://www.pythian.com/blog/prepare-for-the-leap-second/ for an excellent comprehensive guidance and analysis which will help everyone to be prepared for the Leap Second.