second

Applies to VAST Cluster 5.5.

Functions › Date and time functions › Parts of a date or time. Returns the whole second of a timestamp or time of day, from 0 to 59, or the whole seconds of an interval. The fraction of the second is dropped.

Syntax

second(value)

Returns: BIGINT.

Same as: date_part('second', value) and extract(second FROM value); see date_part.

Set up the examples

The examples connect with the ADBC driver, as in VAST Query Engine (ADBC), and work in a schema called docs_sql_fn_date_time_second. Set QE_ENDPOINT, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and VASTDB_BUCKET (SQL reference), and run the blocks in order in one Python session. Below each block is the output you should see.

This block connects, defines the run() and plan() helpers, and creates a table of five events. Each has a date (d), a timestamp (ts), a time of day (t) and a timestamp with nanoseconds (tns). Row 4 has no values, and row 5 is the last moment of 1969:

import os
import re

import adbc_driver_manager
import adbc_driver_manager.dbapi as dbapi
import adbc_driver_vastdb

BUCKET = os.environ["VASTDB_BUCKET"]
SCHEMA = f'"{BUCKET}/docs_sql_fn_date_time_second"'

conn = dbapi.connect(
    driver=adbc_driver_vastdb.get_driver_path(),
    db_kwargs={
        "vast.db.endpoint": os.environ["QE_ENDPOINT"],
        "vast.db.access_key": os.environ["AWS_ACCESS_KEY_ID"],
        "vast.db.secret_key": os.environ["AWS_SECRET_ACCESS_KEY"],
    },
    autocommit=True,
)

def server_message(e):
    """The server's message in a driver error, without the request ID or the echoed statement."""
    text = re.sub(r"\[req=0x[0-9a-f]+\]: ", "", str(e))
    found = (re.search(r'message: "(.*?)", request_id', text, re.S)
             or re.search(r"description: (.*)\)", text, re.S))
    message = found.group(1) if found else text.strip().splitlines()[-1]
    message = re.sub(r"^Plan query: '.*?' failed with: ", "", message, flags=re.S)
    message = re.split(r"\\n|\n", message)[0].replace('\\"', '"')
    return message.replace(BUCKET, "<bucket>")

def run(sql):
    """Run one statement. Print the rows it returns, or the error."""
    try:
        with conn.cursor() as cur:
            cur.execute(sql)
            rows = cur.fetchall() if cur.description else []
    except (adbc_driver_manager.Error, OSError) as e:
        print(f"{type(e).__name__}: {server_message(e)}")
    else:
        print(rows)

def plan(sql):
    """Print the plan without its ~N Rows lines: the table's row count, which can still be 0 just after an insert."""
    with conn.cursor() as cur:
        cur.execute("EXPLAIN " + sql)
        steps = cur.fetchall()[0][1]
    print("\n".join(line for line in steps.splitlines() if "Rows" not in line))

TABLE = f"{SCHEMA}.events"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, d DATE, ts TIMESTAMP, t TIME, tns TIMESTAMP_NS)")
run(f"INSERT INTO {TABLE} VALUES "
    "(1, DATE '2026-02-28', TIMESTAMP '2026-02-28 23:15:00', TIME '23:15:00', "
    "CAST('2026-02-28 23:15:00.123456789' AS TIMESTAMP_NS)), "
    "(2, DATE '2026-03-01', TIMESTAMP '2026-03-01 08:30:45.123456', TIME '08:30:45.123456', "
    "CAST('2026-03-01 08:30:45.123456' AS TIMESTAMP_NS)), "
    "(3, DATE '2024-12-30', TIMESTAMP '2024-12-30 12:00:00', TIME '12:00:00', "
    "CAST('2024-12-30 12:00:00' AS TIMESTAMP_NS)), "
    "(4, NULL, NULL, NULL, NULL), "
    "(5, DATE '1969-12-31', TIMESTAMP '1969-12-31 23:59:59.999999', TIME '23:59:59.999999', "
    "CAST('1969-12-31 23:59:59.999999999' AS TIMESTAMP_NS))")

[]
[]
[(5,)]

What it does

second returns the whole second of a timestamp or time of day, and drops the fraction: second(TIMESTAMP '2024-02-29 13:45:30.123456') is 30, and second(TIME '00:00:59.999999') is 59. It works on every timestamp precision (TIMESTAMP, TIMESTAMP_NS, TIMESTAMP_MS, TIMESTAMP_S). A DATE has no time, so its second is always 0.

To keep the fraction, use millisecond or microsecond. They return the seconds part including the whole seconds, in smaller units:

On an INTERVAL, second returns the whole seconds within the minute of its time part:

NULLs and edge cases

The same cases, as the cluster returns them. They use the table and helpers from Set up the examples:

run(f"SELECT id, second(ts), second(t) FROM {TABLE} WHERE id = 4")
run("SELECT second(DATE 'infinity'), second(TIMESTAMP '-infinity'), second(DATE '2026-03-01'), "
    "second(TIME '00:00:59.999999'), second(TIMESTAMP '1969-12-31 23:59:59.999999'), "
    "second(TIMETZ '13:45:30.123456+02:30')")
run("SELECT second(INTERVAL '1 year 2 months 3 days 04:05:06.789'), second(INTERVAL '90 seconds'), "
    "second(INTERVAL '1.5 seconds'), second(INTERVAL '-0.5 seconds'), "
    "second(INTERVAL '-1 year -2 months -3 days -04:05:06.789')")
run("SELECT second(NULL)")
run("SELECT second('13:45:30')")
run("SELECT second(123)")

[(4, None, None)]
[(None, None, 0, 59, 59, 30)]
[(6, 30, 1, 0, -6)]
InternalError: Binder Error: Could not choose a best candidate function for the function call "second("NULL")". In order to select one, please add explicit type casts.
InternalError: Binder Error: Could not choose a best candidate function for the function call "second(STRING_LITERAL)". In order to select one, please add explicit type casts.
InternalError: Binder Error: No function matches the given name and argument types 'second(INTEGER_LITERAL)'. You might need to add explicit type casts.

Examples

The second of each event's timestamp and time of day, and the same with the fraction, in milliseconds:

run(f"SELECT id, second(ts), millisecond(ts), second(t) FROM {TABLE} ORDER BY id LIMIT 10")

[(1, 0, 0, 0), (2, 45, 45123, 45), (3, 0, 0, 0), (4, None, None, None), (5, 59, 59999, 59)]

Keep only the events that happened exactly on a minute (second 0):

run(f"SELECT id FROM {TABLE} WHERE second(ts) = 0 ORDER BY id LIMIT 10")

[(1,), (3,)]

How it runs in VAST

The Query Engine runs on the cluster's CNodes, and a query on a table starts with a scan in VAST DataBase (VAST_SCAN). VAST DataBase can evaluate a comparison of a column with a constant, but not a function of a column, so second() is always computed by the Query Engine:

• In the SELECT list, the scan reads the column and the Query Engine computes second() for each row it returns.
• In WHERE, the scan sends the column for every row, and a FILTER step in the Query Engine computes second() and keeps the rows that match. No rows are skipped in storage.

The plan of the WHERE example shows the FILTER step above the scan:

plan(f"SELECT id FROM {TABLE} WHERE second(ts) = 0")

┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│     ("second"(ts) = 0)    │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│             ts            │
│             id            │
│                           │
└───────────────────────────┘

Make it faster

• Combine it with a range on the raw column. In ts >= TIMESTAMP '2026-03-01 00:00:00' AND ts < TIMESTAMP '2026-03-02 00:00:00' AND second(ts) = 0, the range is still evaluated in VAST DataBase, so second() runs only on the rows of that day. The plan's FILTER step holds only the second() condition:

plan(f"SELECT id FROM {TABLE} WHERE ts >= TIMESTAMP '2026-03-01 00:00:00' AND ts < TIMESTAMP '2026-03-02 00:00:00' "
     "AND second(ts) = 0")

┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│     ("second"(ts) = 0)    │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│             ts            │
│             id            │
│                           │
└───────────────────────────┘

• Store the second if you filter on it often. Compute it when you write the rows and keep it in its own column: event_second = 0 is pushed down, second(ts) = 0 isn't.

Limitations and errors

• No time-zone support. On a TIMESTAMP WITH TIME ZONE value, such as now(), second fails with an Extension Autoloading Error. Cast the value to TIMESTAMP first; see time zones.
• Whole seconds only. second drops the fraction; it doesn't round. Use millisecond, microsecond or nanosecond for the fraction.
• No leap seconds. A time with second 60, such as TIMESTAMP '2016-12-31 23:59:60', isn't a valid value and fails with invalid timestamp field format.
• TIMESTAMP_NS just before 1970. Row 5's tns, 1969-12-31 23:59:59.999999999, gives 0, not 59. Store such values as TIMESTAMP if you need their second.

run(f"SELECT id, second(tns), second(ts) FROM {TABLE} ORDER BY id LIMIT 10")
run("SELECT TIMESTAMP '2016-12-31 23:59:60'")

[(1, 0, 0), (2, 45, 45), (3, 0, 0), (4, None, None), (5, 0, 59)]
OSError: invalid timestamp field format: "2016-12-31 23:59:60", expected format is (YYYY-MM-DD HH:MM:SS[.US][±HH:MM| ZONE])

Similar functions

run("SELECT second(TIMESTAMP '2024-02-29 13:45:30.123456'), millisecond(TIMESTAMP '2024-02-29 13:45:30.123456'), "
    "microsecond(TIMESTAMP '2024-02-29 13:45:30.123456'), minute(TIMESTAMP '2024-02-29 13:45:30.123456'), "
    "date_trunc('second', TIMESTAMP '2024-02-29 13:45:30.123456'), strftime(TIMESTAMP '2024-02-29 13:45:30.123456', '%S')")

[(30, 30123, 30123456, 45, datetime.datetime(2024, 2, 29, 13, 45, 30), '30')]

Clean up:

run(f"DROP TABLE IF EXISTS {TABLE}")
run(f"DROP SCHEMA IF EXISTS {SCHEMA}")
conn.close()

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See also

• date_part: any part of a value, by name.
• Date and time functions: all the date and time functions.
• Where filters run and pushdowns.
• EXPLAIN: how to read a plan.