Yes, the precision of calls to the system clock is typically significantly better than milliseconds, and the "maximum possible precision" would be even more digits than `YYYY-MM-SSTHH:MM:SS.SSS` . Details depend of course on the hardware. A format like YYYY-MM-SSTHH:MM:SS.SSS suggests to me as a physicist that it is an absolute time value, and I expect the number of digits to roughly represent the accuracy of this value. For time differences (where precision rather than accuracy is the issue) it is a rather clumsy format. For example, in Sqlite `julianday('now')` would be suitable for differences. But I guess that this is even less standard than CURRENT_TIMESTAMP across different database systems.