Language reference
SECOND (extract second)
Syntax
SECOND(<time-or-timestamp>)
π id, SECOND(captured_at) → sec (Samples)Description
SECOND pulls the seconds part (0–59) out of a time or timestamp — the finest whole-second component.
Technical Description
SECOND(t) → NUMBER (0–59). Accepts a TIME or TIMESTAMP (read at UTC); other types are an evaluation error. NULL input returns NULL. PURE, DETERMINISTIC.
Examples
Readings captured exactly on the minute (a sign of a scheduled, not sampled, feed):
σ SECOND(captured_at) = 0 (Samples)SELECT SECOND(captured_at) = 0 (Samples)Spot a burst — how many events landed in each second of a minute:
γ SECOND(occurred_at) → sec, COUNT(id) → hits (Events)GROUP SECOND(occurred_at) -> sec, COUNT(id) -> hits (Events)Pushdown
SQL: folds to EXTRACT(SECOND FROM <col>) on every dialect but SQLite, which has no date type to extract from. On SQL Server, which has no EXTRACT, it is DATEPART(SECOND, SWITCHOFFSET(<col>, '+00:00')) — the value switched to UTC first, so a DATETIMEOFFSET is read at UTC as the engine reads it. MongoDB: folds to {"$second": "$<col>"} inside a $project stage (requires alias).
Limitations
Argument must be a TIME or TIMESTAMP. Returns whole seconds 0–59 (no fractional part). TIMESTAMP at UTC. NULL in → NULL out.