Re: %TIMESTAMP question

[Vern Hamberg <vhamberg@xxxxxxxxxxxxxxx>]

This uniqueness thing, and the 12-digits setting, have been intriguing. 
I have had reason to work with the MI function MATTOD - Materialize Time 
of Day. This returns an 8-byte value, the most left-hand bits contain a 
count of the ticks of the system clock. Now in an article, at 
https://www.ibm.com/support/pages/difference-between-time-opcode-rpg-and-mi-instruction-mattod, 
last modified in July, 2021, it says that the system clock resolution  
is +/- 8 microseconds. In the TOD value, the right-hand bits provide 
uniqueness - as that article says, "Note:  On more powerful IBM i 
models, the MATTOD instruction can run fast enough that multiple 
invocations of it completes within the same 8-microsecond window, 
therefore, returning identical timestamps."

Since 7.1, at least, I think the resolution is now +/- 1 microsecond - 
the number of bits in that TOD, which used to be the count of 
8-microsecond ticks, has been changed. Now since it changed, it is the 
#51 bit from the left, counting from 0. All the remaining bits are a 
uniqueness value. There will likely be someone to confirm this, the 
recent MI C/C++ manual says it is a count of microseconds.

Anyhow, why do I mention all this? Because of the recent uniqueness 
stuff in the timestamp data type. I don't know that the uniqueness comes 
from those bits in the TOD value - that is 12 bits, and the largest 
value in 12 bits is 4096, right? In the datatype, the uniqueness digits 
are 6, so up to 999999, right?

Still, when Barbara says that the true resolution is still microseconds, 
that does match what I understand of that current TOD structure.

OK, enough rambling while watching the Gophers beating Michigan State in 
hockey!!
Regards
Vern

On 2/4/2022 5:27 PM, Barbara Morris wrote:
> On 2022-02-03 11:22 p.m., Birgitta Hauser wrote:
> > If you need all 12 digits, you can use the SQL Timestamp, you can get 
> > all 12
> > digits:
> >
> > Exec SQL Set :YourTimestamp = Current_Timestamp(12);
>
> Current_Timestamp(12) is similar to %TIMESTAMP(*UNIQUE) in that the 
> returned timestamp has only microsecond precision. The last 6 digits 
> are "uniqueness" digits; they don't add any extra accuracy to the 
> timestamp.