List clock-ins

Marks inside a window of days, oldest first.

The window is required and capped at 90 days. This is the largest table in the product; an unbounded read of it has no plan that finishes. date_from and date_to are plain dates matched against the clock the mark was stamped with, not against an instant — a day means the same thing here as it does to the person who worked it.

datetime is the moment as it was recorded, offset included — the stored wall clock read in the stored zone, never shifted anywhere else. It is one field because it is one fact: the wall clock is the value without its offset, and the zone is the offset. On the rare row whose zone cannot be read it comes back with no offset at all, which is how you see that the zone was not known.

status is in, out or break, not the integer the column keeps.

Late arrivals are the one thing to plan for: a device that was offline uploads what it recorded earlier, so a mark can appear inside a window you have already read. Re-read the last few days with overlap rather than paging strictly forward and never looking back.