isoyear

Applies to VAST Cluster 5.5.

Functions › Date and time functions › Weeks and days of the week. Returns the ISO 8601 year of a date or timestamp: the year that its ISO week belongs to. Near New Year it can differ from the calendar year.

Syntax

isoyear(value)

Returns: BIGINT.

Same as: date_part('isoyear', 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_isoyear. 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 seven 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, row 6 is the last moment of 1969, and row 7 is a Sunday early in January 2027:

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_isoyear"'

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 '2024-02-29', TIMESTAMP '2024-02-29 00:00:00', TIME '00:00:00', "
    "CAST('2024-02-29 00:00:00' AS TIMESTAMP_NS)), "
    "(6, 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)), "
    "(7, DATE '2027-01-03', TIMESTAMP '2027-01-03 00:00:00.5', TIME '00:00:00.000001', "
    "CAST('2027-01-03 00:00:00.5' AS TIMESTAMP_NS))")

[]
[]
[(7,)]

What it does

ISO 8601 weeks start on Monday, and week 1 of a year is the week that holds the year's first Thursday. Every day belongs to exactly one ISO week, and isoyear returns the year of that week. For most of the year it's the calendar year; in the first and last days of a year it can be one more or one less:

Use isoyear together with week, which is the ISO week number: week alone can't tell week 1 of 2025 from week 1 of 2024. yearweek gives both as one number.

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, isoyear(ts) FROM {TABLE} WHERE id = 4")
run("SELECT isoyear(DATE '2024-12-30'), isoyear(DATE '2021-01-01'), isoyear(DATE '2027-01-03'), "
    "isoyear(DATE '2027-01-04')")
run("SELECT isoyear(DATE 'infinity'), isoyear(TIMESTAMP '-infinity'), isoyear(DATE '0001-01-01'), "
    "isoyear(DATE '9999-12-31'), isoyear(CAST('0044-03-15 (BC)' AS DATE)), "
    "isoyear(TIMESTAMP '1969-12-31 23:59:59.999999')")
run("SELECT isoyear(NULL)")
run("SELECT isoyear(INTERVAL '1 year 2 months 3 days')")
run("SELECT isoyear(TIME '13:45:30')")
run("SELECT isoyear('2026-03-01')")
run("SELECT isoyear(123)")

[(4, None)]
[(2025, 2020, 2026, 2027)]
[(None, None, 1, 9999, -43, 1970)]
InternalError: Binder Error: Could not choose a best candidate function for the function call "isoyear("NULL")". In order to select one, please add explicit type casts.
OSError: interval units "isoyear" not recognized
InternalError: Binder Error: No function matches the given name and argument types 'isoyear(TIME)'. You might need to add explicit type casts.
InternalError: Binder Error: Could not choose a best candidate function for the function call "isoyear(STRING_LITERAL)". In order to select one, please add explicit type casts.
InternalError: Binder Error: No function matches the given name and argument types 'isoyear(INTEGER_LITERAL)'. You might need to add explicit type casts.

Examples

The calendar year and the ISO year of each event. They differ for rows 3, 6 and 7:

run(f"SELECT id, d, year(d), isoyear(d) FROM {TABLE} ORDER BY id LIMIT 10")

[(1, datetime.date(2026, 2, 28), 2026, 2026), (2, datetime.date(2026, 3, 1), 2026, 2026), (3, datetime.date(2024, 12, 30), 2024, 2025), (4, None, None, None), (5, datetime.date(2024, 2, 29), 2024, 2024), (6, datetime.date(1969, 12, 31), 1969, 1970), (7, datetime.date(2027, 1, 3), 2027, 2026)]

The ISO year and week of each event, for weekly reports:

run(f"SELECT id, isoyear(d), week(d) FROM {TABLE} ORDER BY id LIMIT 10")

[(1, 2026, 9), (2, 2026, 9), (3, 2025, 1), (4, None, None), (5, 2024, 9), (6, 1970, 1), (7, 2026, 53)]

Keep only the events whose ISO year isn't their calendar year:

run(f"SELECT id FROM {TABLE} WHERE isoyear(d) <> year(d) ORDER BY id LIMIT 10")

[(3,), (6,), (7,)]

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 isoyear() is always computed by the Query Engine:

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

The plan of a filter on the ISO year shows the FILTER step above the scan:

plan(f"SELECT id FROM {TABLE} WHERE isoyear(d) = 2025")

┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│    (isoyear(d) = 2025)    │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│             d             │
│             id            │
│                           │
└───────────────────────────┘

Make it faster

• For one ISO year, filter on a range of the raw column. ISO year 2025 runs from Monday 30 December 2024 to Sunday 28 December 2025, so d >= DATE '2024-12-30' AND d < DATE '2025-12-29' selects the same rows as isoyear(d) = 2025. The range is pushed down to VAST DataBase, so rows outside it never leave storage. The plan for the range has no FILTER step:

plan(f"SELECT id FROM {TABLE} WHERE d >= DATE '2024-12-30' AND d < DATE '2025-12-29'")

┌───────────────────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│      Projections: id      │
│                           │
└───────────────────────────┘

• Store the ISO year if you filter on it often. Compute it when you write the rows and keep it in its own column: iso_year = 2025 is pushed down, isoyear(d) = 2025 isn't.

Limitations and errors

• No time-zone support. On a TIMESTAMP WITH TIME ZONE value, such as now(), isoyear fails with an Extension Autoloading Error. Cast the value to TIMESTAMP first; see time zones.
• Not for TIME or INTERVAL. The error for an INTERVAL lists isoyear(INTERVAL) among the candidates, but running it fails with interval units "isoyear" not recognized. date_part('isoyear', ...) on a TIME fails with "time" units "isoyear" not recognized.

run("SELECT date_part('isoyear', TIME '13:45:30')")

OSError: "time" units "isoyear" not recognized

Similar functions

run("SELECT isoyear(DATE '2024-12-30'), year(DATE '2024-12-30'), week(DATE '2024-12-30'), "
    "yearweek(DATE '2024-12-30'), strftime(DATE '2024-12-30', '%G'), date_part('isoyear', DATE '2024-12-30')")

[(2025, 2024, 1, 202501, '2025', 2025)]

Clean up:

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

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See also

• week and yearweek: the ISO week.
• Date and time functions: all the date and time functions.
• Where filters run and pushdowns.
• EXPLAIN: how to read a plan.