--- title: "+ (add a date or interval)" slug: "dev-database-reference-sql-functions-date-time-plus" updated: 2026-10-30T18:19:01Z published: 2026-10-30T18:19:01Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-date-time-plus" --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.vastdata.com/llms.txt > Use this file to discover all available pages before exploring further. # + (add a date or interval) *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Date and time functions](/develop/docs/dev-database-reference-sql-functions-date-time) › Adding and interval arithmetic.* Moves a date, timestamp or time forward by an interval, adds a number of days to a date, joins a date and a time into a timestamp, or adds two intervals. `add(a, b)` is the same function, and [date_add](/develop/docs/dev-database-reference-sql-functions-date-time-date-add) is a shorthand for it. For adding numbers, see [+ (addition)](/develop/docs/dev-database-reference-sql-functions-operators-addition). ## Syntax ``` date + days days + date date + time value + interval interval + value interval + interval add(a, b) ``` | Argument | Type | Description | | --- | --- | --- | | `date` | `DATE` | A date. | | `days` | `INTEGER` or `SMALLINT` | A number of days; negative goes back. A `BIGINT` doesn't work: cast it to `INTEGER`. | | `time` | `TIME` | A time of day, joined to `date` to make a timestamp. | | `value` | `DATE`, `TIMESTAMP` (also `TIMESTAMP_NS` and `TIMESTAMP_MS`) or `TIME` | The value to move. | | `interval` | `INTERVAL` | The time to add, such as `INTERVAL 1 MONTH`, `INTERVAL '1 day 2 hours'` or `to_days(n)`. | **Returns:** | Expression | Result | | --- | --- | | `DATE + INTEGER`, `INTEGER + DATE` | `DATE` | | `DATE + TIME`, `TIME + DATE` | `TIMESTAMP` | | `DATE + INTERVAL`, `INTERVAL + DATE` | `TIMESTAMP`, also when the interval is whole days | | `TIMESTAMP + INTERVAL`, `INTERVAL + TIMESTAMP` | `TIMESTAMP`, for every timestamp precision | | `TIME + INTERVAL`, `INTERVAL + TIME` | `TIME`, wrapping past midnight | | `INTERVAL + INTERVAL` | `INTERVAL` | **Aliases:** `add(a, b)`. ## Set up the examples The examples connect with the ADBC driver, as in [VAST Query Engine (ADBC)](/develop/docs/dev-database-integrations-adbc), and work in a schema called `docs_sql_fn_date_time_plus`. Set `QE_ENDPOINT`, `AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY` and `VASTDB_BUCKET` ([SQL reference](/develop/docs/dev-database-reference-sql-index#example-connect-and-use-a-transaction)), 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 with a date (`d`), a timestamp (`ts`), a time of day (`t`) and a number of days (`n`, an `INTEGER`). Row 4 has no values: ``` 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_plus"' 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, "") 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, n INTEGER)") run(f"INSERT INTO {TABLE} VALUES " "(1, DATE '2026-02-28', TIMESTAMP '2026-02-28 23:15:00', TIME '23:15:00', 1), " "(2, DATE '2026-03-01', TIMESTAMP '2026-03-01 08:30:45.123456', TIME '08:30:45.123456', -2), " "(3, DATE '2024-12-30', TIMESTAMP '2024-12-30 12:00:00', TIME '12:00:00', 0), " "(4, NULL, NULL, NULL, NULL), " "(5, DATE '2024-02-29', TIMESTAMP '2024-02-29 00:00:00', TIME '00:00:00', 12)") ``` ``` [] [] [(5,)] ``` ## What it does An `INTERVAL` has three separate fields, months, days and time, and `+` applies them in that order: - **Months and years** move the calendar month and keep the day of the month; when the day doesn't exist, the result is the month's last day. `DATE '2026-01-31' + INTERVAL 1 MONTH` is `2026-02-28`, and `DATE '2024-02-29' + INTERVAL 1 YEAR` is `2025-02-28`. - **Days** move whole days: `DATE '2026-01-30' + INTERVAL '1 month 1 day'` is `2026-02-28` plus one day, `2026-03-01`. - **Time** moves the clock: `TIMESTAMP '2024-02-29 23:59:59' + INTERVAL 1 SECOND` is `2024-03-01 00:00:00`. `INTERVAL '1.5 days'` is one day and twelve hours. On a `TIME`, only the time field counts and the result wraps: `TIME '23:30:00' + INTERVAL 1 HOUR` is `00:30:00`, and adding a day or a month leaves a time unchanged. There are no time zones, so there are no daylight-saving jumps: `TIMESTAMP '2026-03-29 01:30:00' + INTERVAL 1 HOUR` is `02:30:00`. `INTERVAL + INTERVAL` adds field by field and doesn't convert between them: `INTERVAL 1 MONTH + INTERVAL 30 DAY` is one month and 30 days. `+` is evaluated left to right, so `d + INTERVAL 1 MONTH + INTERVAL 1 MONTH` moves one month at a time (`2026-01-31` gives `2026-03-28`), while `d + INTERVAL 2 MONTH` gives `2026-03-31`. ## NULLs and edge cases | Input | Result | | --- | --- | | A NULL value (row 4), `NULL::DATE + 1`, `DATE '2026-01-01' + NULL`, `ts + NULL::INTERVAL` | `NULL` | | An untyped `NULL`: `NULL + INTERVAL 1 MONTH` | Error: `Could not choose a best candidate function for the function call "+("NULL", INTERVAL)"`; use `NULL::TIMESTAMP` | | `DATE 'infinity' + 1`, `DATE 'infinity' + INTERVAL 1 DAY` | `infinity` | | `DATE '9999-12-31' + 1` | `10000-01-01`, which Python's `datetime` can't hold: `CAST` it to `VARCHAR` | | A date or timestamp past the supported range: `DATE '2026-01-01' + 2147483647`, `ts + INTERVAL 300000 YEAR` | Error: `Date out of range`; `Date and time not in timestamp range` | | Intervals that overflow: `INTERVAL '2147483647 months' + INTERVAL 1 MONTH` | Error: `Overflow in addition of INT32 (2147483647 + 1)!` | | A `BIGINT` number of days: `d + id` | Error: `No function matches the given name and argument types '+(DATE, BIGINT)'`; use `d + CAST(id AS INTEGER)` | | A fraction of a day: `DATE '2026-01-01' + 1.5` | Error: `No function matches the given name and argument types '+(DATE, DECIMAL(2,1))'`; add `INTERVAL 36 HOUR` | | A number added to a `TIMESTAMP` or `TIME`: `ts + 1` | Error: `No function matches the given name and argument types '+(TIMESTAMP, INTEGER_LITERAL)'`; add an `INTERVAL` | | Two dates, two times, or a `TIMESTAMP` and a `TIME` | Error: `No function matches the given name and argument types`, for example `'+(DATE, DATE)'` | | A string: `DATE '2026-01-01' + '1'`, `'abc' + INTERVAL 1 MONTH` | Error: `Could not choose a best candidate function`; cast it | | Unary `+` on a date or an interval: `+INTERVAL 1 DAY` | Error: `No function matches the given name and argument types '+(INTERVAL)'` | The same cases, as the cluster returns them. They use the table and helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-date-time-plus#set-up-the-examples): ``` run(f"SELECT id, d + n, ts + INTERVAL 1 MONTH FROM {TABLE} WHERE id = 4") run("SELECT NULL::DATE + 1, DATE '2026-01-01' + NULL, TIMESTAMP '2026-01-01 00:00:00' + NULL::INTERVAL, " "CAST(DATE 'infinity' + 1 AS VARCHAR), CAST(DATE 'infinity' + INTERVAL 1 DAY AS VARCHAR), " "CAST(DATE '9999-12-31' + 1 AS VARCHAR)") run("SELECT NULL + INTERVAL 1 MONTH") run("SELECT DATE '2026-01-01' + 2147483647") run("SELECT TIMESTAMP '2026-01-01 00:00:00' + INTERVAL 300000 YEAR") run("SELECT INTERVAL '2147483647 months' + INTERVAL 1 MONTH") run(f"SELECT id, d + id FROM {TABLE} ORDER BY id LIMIT 10") run(f"SELECT id, d + CAST(id AS INTEGER) FROM {TABLE} ORDER BY id LIMIT 10") run("SELECT DATE '2026-01-01' + 1.5") run("SELECT TIMESTAMP '2026-01-01 00:00:00' + 1") run("SELECT DATE '2026-01-01' + DATE '2026-01-01'") run("SELECT DATE '2026-01-01' + '1'") run("SELECT +INTERVAL 1 DAY") ``` ``` [(4, None, None)] [(None, None, None, 'infinity', 'infinity', '10000-01-01')] InternalError: Binder Error: Could not choose a best candidate function for the function call "+("NULL", INTERVAL)". In order to select one, please add explicit type casts. OSError: Date out of range OSError: Date and time not in timestamp range OSError: Overflow in addition of INT32 (2147483647 + 1)! InternalError: Binder Error: No function matches the given name and argument types '+(DATE, BIGINT)'. You might need to add explicit type casts. [(1, datetime.date(2026, 3, 1)), (2, datetime.date(2026, 3, 3)), (3, datetime.date(2025, 1, 2)), (4, None), (5, datetime.date(2024, 3, 5))] InternalError: Binder Error: No function matches the given name and argument types '+(DATE, DECIMAL(2,1))'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types '+(TIMESTAMP, INTEGER_LITERAL)'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types '+(DATE, DATE)'. You might need to add explicit type casts. InternalError: Binder Error: Could not choose a best candidate function for the function call "+(DATE, STRING_LITERAL)". In order to select one, please add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types '+(INTERVAL)'. You might need to add explicit type casts. ``` The month-end, leap-day, time and interval cases from [What it does](/develop/docs/dev-database-reference-sql-functions-date-time-plus#what-it-does): ``` run("SELECT DATE '2026-01-31' + INTERVAL 1 MONTH, DATE '2024-02-29' + INTERVAL 1 YEAR, " "DATE '2026-01-30' + INTERVAL '1 month 1 day', TIMESTAMP '2024-02-29 23:59:59' + INTERVAL 1 SECOND, " "TIMESTAMP '2026-03-01 00:00:00' + INTERVAL '1.5 days'") run("SELECT TIME '23:30:00' + INTERVAL 1 HOUR, TIME '23:59:59' + INTERVAL 1 DAY, TIME '08:00:00' + INTERVAL 1 MONTH, " "TIMESTAMP '2026-03-29 01:30:00' + INTERVAL 1 HOUR") run("SELECT INTERVAL 1 MONTH + INTERVAL 30 DAY, DATE '2026-01-31' + INTERVAL 1 MONTH + INTERVAL 1 MONTH, " "DATE '2026-01-31' + INTERVAL 2 MONTH") ``` ``` [(datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2025, 2, 28, 0, 0), datetime.datetime(2026, 3, 1, 0, 0), datetime.datetime(2024, 3, 1, 0, 0), datetime.datetime(2026, 3, 2, 12, 0))] [(datetime.time(0, 30), datetime.time(23, 59, 59), datetime.time(8, 0), datetime.datetime(2026, 3, 29, 2, 30))] [(MonthDayNano(months=1, days=30, nanoseconds=0), datetime.datetime(2026, 3, 28, 0, 0), datetime.datetime(2026, 3, 31, 0, 0))] ``` ## Examples The next day, `n` days later, and each date at its time of day: ``` run(f"SELECT id, d + 1, d + n, d + t FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, datetime.date(2026, 3, 1), datetime.date(2026, 3, 1), datetime.datetime(2026, 2, 28, 23, 15)), (2, datetime.date(2026, 3, 2), datetime.date(2026, 2, 27), datetime.datetime(2026, 3, 1, 8, 30, 45, 123456)), (3, datetime.date(2024, 12, 31), datetime.date(2024, 12, 30), datetime.datetime(2024, 12, 30, 12, 0)), (4, None, None, None), (5, datetime.date(2024, 3, 1), datetime.date(2024, 3, 12), datetime.datetime(2024, 2, 29, 0, 0))] ``` A month after each timestamp, a month and a day after it, and `n` days after it, with the interval built from the column in two ways: ``` run(f"SELECT id, ts + INTERVAL 1 MONTH, INTERVAL '1 month 1 day' + ts FROM {TABLE} ORDER BY id LIMIT 10") run(f"SELECT id, ts + INTERVAL (n) DAY, ts + to_days(n) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, datetime.datetime(2026, 3, 28, 23, 15), datetime.datetime(2026, 3, 29, 23, 15)), (2, datetime.datetime(2026, 4, 1, 8, 30, 45, 123456), datetime.datetime(2026, 4, 2, 8, 30, 45, 123456)), (3, datetime.datetime(2025, 1, 30, 12, 0), datetime.datetime(2025, 1, 31, 12, 0)), (4, None, None), (5, datetime.datetime(2024, 3, 29, 0, 0), datetime.datetime(2024, 3, 30, 0, 0))] [(1, datetime.datetime(2026, 3, 1, 23, 15), datetime.datetime(2026, 3, 1, 23, 15)), (2, datetime.datetime(2026, 2, 27, 8, 30, 45, 123456), datetime.datetime(2026, 2, 27, 8, 30, 45, 123456)), (3, datetime.datetime(2024, 12, 30, 12, 0), datetime.datetime(2024, 12, 30, 12, 0)), (4, None, None), (5, datetime.datetime(2024, 3, 12, 0, 0), datetime.datetime(2024, 3, 12, 0, 0))] ``` Ninety minutes after each time of day, and the same with `add()`: ``` run(f"SELECT id, t + INTERVAL 90 MINUTE, add(t, INTERVAL 90 MINUTE), add(d, n) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, datetime.time(0, 45), datetime.time(0, 45), datetime.date(2026, 3, 1)), (2, datetime.time(10, 0, 45, 123456), datetime.time(10, 0, 45, 123456), datetime.date(2026, 2, 27)), (3, datetime.time(13, 30), datetime.time(13, 30), datetime.date(2024, 12, 30)), (4, None, None, None), (5, datetime.time(1, 30), datetime.time(1, 30), datetime.date(2024, 3, 12))] ``` Keep only the events whose timestamp plus one hour is after 1 March 2026: ``` run(f"SELECT id FROM {TABLE} WHERE ts + INTERVAL 1 HOUR > TIMESTAMP '2026-03-01 00:00:00' ORDER BY id LIMIT 10") ``` ``` [(1,), (2,)] ``` ## 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 an expression on a column, so `+` on a column is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine adds to it for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes the sum and keeps the rows that match. No rows are skipped in storage. - **On constants only,** as in `TIMESTAMP '2026-01-15 00:00:00' + INTERVAL 1 DAY`, the sum is computed once, and a comparison of a column with it is pushed down. The plan of the `WHERE` example shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE ts + INTERVAL 1 HOUR > TIMESTAMP '2026-03-01 00:00:00'") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ((ts + '01:00:00': │ │ :INTERVAL) > '2026-03-01 │ │ 00:00:00'::TIMESTAMP) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ ts │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Move the interval to the constant side.** `ts > TIMESTAMP '2026-03-01 00:00:00' - INTERVAL 1 HOUR` keeps the same rows as `ts + INTERVAL 1 HOUR > TIMESTAMP '2026-03-01 00:00:00'`, and it's pushed down to VAST DataBase, so rows that don't match never leave storage. Its plan has no `FILTER` step: ``` run(f"SELECT id FROM {TABLE} WHERE ts > TIMESTAMP '2026-03-01 00:00:00' - INTERVAL 1 HOUR ORDER BY id LIMIT 10") plan(f"SELECT id FROM {TABLE} WHERE ts > TIMESTAMP '2026-03-01 00:00:00' - INTERVAL 1 HOUR") ``` ``` [(1,), (2,)] ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **The same for days on a date:** write `d > DATE '2026-02-28' - 1`, not `d + 1 > DATE '2026-02-28'`. A constant built with `+`, such as `TIMESTAMP '2026-01-15 00:00:00' + to_days(30)`, is pushed down as well: ``` plan(f"SELECT id FROM {TABLE} WHERE d > DATE '2026-02-28' - 1") plan(f"SELECT id FROM {TABLE} WHERE ts > TIMESTAMP '2026-01-15 00:00:00' + to_days(30)") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` ## Limitations and errors - **No time-zone support.** `+` with a `TIMESTAMP WITH TIME ZONE` value, such as `now()`, fails with `No function matches the given name and argument types '+(TIMESTAMP WITH TIME ZONE, INTERVAL)'`. Cast the value to `TIMESTAMP` first: `CAST(now() AS TIMESTAMP) + INTERVAL 1 DAY`. See [time zones](/develop/docs/dev-database-reference-sql-functions-date-time-time-zones). - **Fractions in interval literals need quotes.** `INTERVAL 1.5 DAY` is a syntax error; write `INTERVAL '1.5 days'` or `INTERVAL 36 HOUR`. - **Nanoseconds are dropped.** `TIMESTAMP_NS` plus an interval is a `TIMESTAMP`, with microseconds. ``` run("SELECT now() + INTERVAL 1 DAY") run("SELECT CAST(now() AS TIMESTAMP) + INTERVAL 1 DAY > CAST(now() AS TIMESTAMP)") run("SELECT TIMESTAMP '2026-03-01 00:00:00' + INTERVAL 1.5 DAY") run("SELECT CAST(TIMESTAMP_NS '2026-01-01 00:00:00.000000001' + INTERVAL 1 DAY AS VARCHAR)") ``` ``` InternalError: Binder Error: No function matches the given name and argument types '+(TIMESTAMP WITH TIME ZONE, INTERVAL)'. You might need to add explicit type casts. [(True,)] InternalError: Parse query: 'SELECT TIMESTAMP '2026-03-01 00:00:00' + INTERVAL 1.5 DAY' failed with: Parser Error: syntax error at or near "1.5" [('2026-01-02 00:00:00',)] ``` ## Similar functions | Function or operator | What it does | Result for `DATE '2026-01-31'` | | --- | --- | --- | | `+ INTERVAL 1 MONTH` | Adds one calendar month | `2026-02-28 00:00:00` | | `+ INTERVAL 30 DAY` | Adds 30 days | `2026-03-02 00:00:00` | | `+ 1` | Adds one day, keeping a `DATE` | `2026-02-01` | | [date_add](/develop/docs/dev-database-reference-sql-functions-date-time-date-add), `add()` | The same as `+` | `2026-02-28 00:00:00` | | [-](/develop/docs/dev-database-reference-sql-functions-date-time-minus) | Goes back, or gives the time between two values | | | [to_months](/develop/docs/dev-database-reference-sql-functions-date-time-to-months), [to_days](/develop/docs/dev-database-reference-sql-functions-date-time-to-days) | Build an interval from a number or a column | `+ to_months(1)` is `2026-02-28 00:00:00` | ``` run("SELECT DATE '2026-01-31' + INTERVAL 1 MONTH, DATE '2026-01-31' + INTERVAL 30 DAY, DATE '2026-01-31' + 1, " "date_add(DATE '2026-01-31', INTERVAL 1 MONTH), add(DATE '2026-01-31', INTERVAL 1 MONTH), DATE '2026-01-31' + to_months(1)") ``` ``` [(datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 3, 2, 0, 0), datetime.date(2026, 2, 1), datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 2, 28, 0, 0))] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Date and time functions](/develop/docs/dev-database-reference-sql-functions-date-time): all the date and time functions. - [+ (addition)](/develop/docs/dev-database-reference-sql-functions-operators-addition): adding numbers. - [Where filters run](/develop/docs/dev-database-reference-sql-select#where-filters-run) and [pushdowns](/develop/docs/dev-database-reference-pushdowns). - [EXPLAIN](/develop/docs/dev-database-reference-sql-explain): how to read a plan.