We just argued that storing timestamp in sqlserver in microsoft does guarantee uniqueness, but im a little bit doubful about mysql/mariadb, because we are using parallel execution when inserting to the mysql/mariadb database.

So, Is using timestamp as primary key good idea - mysql/mariadb?

PS: There is always an PK and status but its important if we are using timestamp as the where clause in getting the actual remaining records to be archived/removed (so that it is efficient in querying the records).So its important its unique

  • Please provide the reference about SQL Server. I am very dubious. – Rick James Mar 31 '17 at 3:48
  • I would not trust even microsecond-resolution to be unique. Might work on a single machine today, but what about tomorrow's machine(s), etc. – Rick James Mar 31 '17 at 3:51

IMO it's bad because of several reasons. First, blindly assigning a generated p.k. for every relation is bad practice. At least try to identify what candidate keys there are in each relation. A surregate p.k. may be the smartest choice in some situations, but it is definitely not so in all possible situations. Good properties for candidate keys are:

  • Unique
  • Irreducible
  • Non-complex
  • Stable
  • Familiar

Often there is a conflict between these criteria and you have to sacrifice one for another.

Second, if the best choice is a surrogate identifier I'll say that timestamp is a poor choice. Especially in MySQL/MariaDB before (MySQL) 5.6.4 where the resolution is seconds. Using a timestamp as a p.k in these DBMS means that you cannot insert more than one row / second (as long as the timestamp should reflect the time of insert).

  • are you considering the timestamp data type in mysql/mariadb right? timestamp is a poor choice is also my answer too thanks for enlightening me, – david Mar 28 '17 at 9:05
  • Yes, it was the timestamp I had in mind. In MySQL/MariaDB timestamp is not the same type as in other DBMS:s, it deviates from the standard in several aspects. Choosing another datetime type does not help either since the maximum resolution is second there as well. – Lennart Mar 28 '17 at 10:14

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