--- title: "date_add" slug: "dev-database-reference-sql-functions-date-time-date-add" updated: 2026-10-30T18:19:01Z published: 2026-10-30T18:19:01Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-date-time-date-add" --- > ## 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. # date_add *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.* Adds an interval to a date, timestamp or time, or a number of days to a date. `date_add(a, b)` is a shorthand for `a + b` and works exactly like the [+](/develop/docs/dev-database-reference-sql-functions-date-time-plus) operator: adding a month to the end of a month gives the end of the shorter month, so 31 January plus one month is 28 February. ## Syntax ``` date_add(value, interval) date_add(date, days) ``` | Argument | Type | Description | | --- | --- | --- | | `value` | `DATE`, `TIMESTAMP` (also `TIMESTAMP_NS` and `TIMESTAMP_MS`) or `TIME` | The value to add to. | | `interval` | `INTERVAL` | The time to add; it can be negative, and it can come from columns, as in `to_days(n)`. | | `date`, `days` | `DATE` and `INTEGER` | A number of days to add to a date; negative goes back. | The arguments can also be in the other order (`date_add(INTERVAL 1 DAY, d)`), or a `DATE` and a `TIME`, which gives the timestamp of that time on that day, as with [+](/develop/docs/dev-database-reference-sql-functions-date-time-plus). **Returns:** | Arguments | Result | | --- | --- | | `DATE`, `INTERVAL` | `TIMESTAMP`, also when the interval is whole days | | `TIMESTAMP` (any precision), `INTERVAL` | `TIMESTAMP` | | `TIME`, `INTERVAL` | `TIME`, wrapping past midnight | | `DATE`, `INTEGER` | `DATE` | | `DATE`, `TIME` | `TIMESTAMP` | | `INTERVAL`, `INTERVAL` | `INTERVAL` | ## 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_date_add`. 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_date_add"' 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 `date_add` adds the interval's months first, then its days, then its time: - **Months and years** move the calendar month and keep the day of the month. When that day doesn't exist in the new month, the result is the month's last day: `2026-01-31` plus one month is `2026-02-28`, `2024-01-31` plus one month is `2024-02-29`, and `2024-02-29` plus one year is `2025-02-28` (plus four years, `2028-02-29`). - **Days** move whole calendar days: `2026-01-31` plus `INTERVAL '1 month 1 day'` is `2026-02-28` plus one day, `2026-03-01`. - **Time** moves the clock. On a `TIME` it wraps: `TIME '23:30:00'` plus one hour is `00:30:00`. Add a total interval in one call rather than one month at a time: `date_add(DATE '2026-01-31', INTERVAL 2 MONTH)` is `2026-03-31`, but adding one month and then another gives `2026-03-28`, because the first step stops at 28 February. ## NULLs and edge cases | Input | Result | | --- | --- | | A NULL value (row 4), `NULL::DATE`, `NULL::INTERVAL` or a NULL number of days | `NULL` | | An untyped `NULL` value: `date_add(NULL, INTERVAL 1 MONTH)` | Error: `Could not choose a best candidate function for the function call "+("NULL", INTERVAL)"`; use `NULL::TIMESTAMP` | | A negative interval: `INTERVAL '-1 month'` on `DATE '2026-01-01'` | `2025-12-01` | | Mixed signs: `INTERVAL '1 month -1 day'` on `DATE '2026-03-01'` | `2026-03-31` | | A `TIMESTAMP_NS` value | A `TIMESTAMP`: the nanoseconds are dropped | | A date past the supported range: `date_add(DATE '2026-01-01', 2147483647)` | Error: `Date out of range` | | A fraction of a day: `date_add(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`: `date_add(ts, 1)` | Error: `No function matches the given name and argument types '+(TIMESTAMP, INTEGER_LITERAL)'`; add `INTERVAL 1 DAY` | | A string value, such as `'abc'` | Error: `Could not choose a best candidate function for the function call "+(STRING_LITERAL, INTERVAL)"`; cast it | | Three arguments, as in `date_add('day', 1, d)` | Error: `Macro function date_add(date, interval) requires 2 positional arguments, but 3 positional arguments were provided.` | 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-date-add#set-up-the-examples): ``` run(f"SELECT id, date_add(d, INTERVAL 1 MONTH), date_add(d, n) FROM {TABLE} WHERE id = 4") run("SELECT date_add(NULL::DATE, INTERVAL 1 DAY), date_add(DATE '2026-01-01', NULL::INTERVAL), " "date_add(DATE '2026-01-01', INTERVAL '-1 month'), date_add(DATE '2026-03-01', INTERVAL '1 month -1 day'), " "CAST(date_add(TIMESTAMP_NS '2026-01-01 00:00:00.000000001', INTERVAL 1 DAY) AS VARCHAR)") run("SELECT date_add(NULL, INTERVAL 1 MONTH)") run("SELECT date_add(DATE '2026-01-01', 2147483647)") run("SELECT date_add(DATE '2026-01-01', 1.5)") run("SELECT date_add(TIMESTAMP '2026-01-01 00:00:00', 1)") run("SELECT date_add('abc', INTERVAL 1 MONTH)") run("SELECT date_add('day', 1, DATE '2026-01-01')") ``` ``` [(4, None, None)] [(None, None, datetime.datetime(2025, 12, 1, 0, 0), datetime.datetime(2026, 3, 31, 0, 0), '2026-01-02 00:00:00')] 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 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: Could not choose a best candidate function for the function call "+(STRING_LITERAL, INTERVAL)". In order to select one, please add explicit type casts. InternalError: Binder Error: Macro function date_add(date, interval) requires 2 positional arguments, but 3 positional arguments were provided. ``` The month-end and leap-day cases from [What it does](/develop/docs/dev-database-reference-sql-functions-date-time-date-add#what-it-does), and adding a total against adding one month at a time: ``` run("SELECT date_add(DATE '2026-01-31', INTERVAL 1 MONTH), date_add(DATE '2024-01-31', INTERVAL 1 MONTH), " "date_add(DATE '2026-05-31', INTERVAL 1 MONTH), date_add(DATE '2024-02-29', INTERVAL 1 YEAR), " "date_add(DATE '2024-02-29', INTERVAL 4 YEAR), date_add(DATE '2026-01-31', INTERVAL '1 month 1 day')") run("SELECT date_add(DATE '2026-01-31', INTERVAL 2 MONTH), date_add(DATE '2026-01-31', INTERVAL 1 MONTH + INTERVAL 1 MONTH), " "DATE '2026-01-31' + INTERVAL 1 MONTH + INTERVAL 1 MONTH, date_add(TIME '23:30:00', INTERVAL 1 HOUR)") ``` ``` [(datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2024, 2, 29, 0, 0), datetime.datetime(2026, 6, 30, 0, 0), datetime.datetime(2025, 2, 28, 0, 0), datetime.datetime(2028, 2, 29, 0, 0), datetime.datetime(2026, 3, 1, 0, 0))] [(datetime.datetime(2026, 3, 31, 0, 0), datetime.datetime(2026, 3, 31, 0, 0), datetime.datetime(2026, 3, 28, 0, 0), datetime.time(0, 30))] ``` ## Examples One month after each date, and `n` days after it: ``` run(f"SELECT id, date_add(d, INTERVAL 1 MONTH), date_add(d, n) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, datetime.datetime(2026, 3, 28, 0, 0), datetime.date(2026, 3, 1)), (2, datetime.datetime(2026, 4, 1, 0, 0), datetime.date(2026, 2, 27)), (3, datetime.datetime(2025, 1, 30, 0, 0), datetime.date(2024, 12, 30)), (4, None, None), (5, datetime.datetime(2024, 3, 29, 0, 0), datetime.date(2024, 3, 12))] ``` Ninety minutes after each timestamp and an hour after each time of day; then `n` days after each timestamp, with the interval built from the column: ``` run(f"SELECT id, date_add(ts, INTERVAL 90 MINUTE), date_add(t, INTERVAL 1 HOUR) FROM {TABLE} ORDER BY id LIMIT 10") run(f"SELECT id, date_add(ts, to_days(n)) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, datetime.datetime(2026, 3, 1, 0, 45), datetime.time(0, 15)), (2, datetime.datetime(2026, 3, 1, 10, 0, 45, 123456), datetime.time(9, 30, 45, 123456)), (3, datetime.datetime(2024, 12, 30, 13, 30), datetime.time(13, 0)), (4, None, None), (5, datetime.datetime(2024, 2, 29, 1, 30), datetime.time(1, 0))] [(1, datetime.datetime(2026, 3, 1, 23, 15)), (2, datetime.datetime(2026, 2, 27, 8, 30, 45, 123456)), (3, datetime.datetime(2024, 12, 30, 12, 0)), (4, None), (5, datetime.datetime(2024, 3, 12, 0, 0))] ``` Each date at its time of day, as one timestamp: ``` run(f"SELECT id, date_add(d, t) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, datetime.datetime(2026, 2, 28, 23, 15)), (2, datetime.datetime(2026, 3, 1, 8, 30, 45, 123456)), (3, datetime.datetime(2024, 12, 30, 12, 0)), (4, None), (5, datetime.datetime(2024, 2, 29, 0, 0))] ``` Keep only the events whose next day starts after 1 March 2026: ``` run(f"SELECT id FROM {TABLE} WHERE date_add(d, INTERVAL 1 DAY) > TIMESTAMP '2026-03-01 00:00:00' ORDER BY id LIMIT 10") ``` ``` [(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 `date_add()` on a column is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine computes `date_add()` for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes `date_add()` 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 date_add(d, INTERVAL 1 DAY) > TIMESTAMP '2026-03-01 00:00:00'") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ((d + '1 day'::INTERVAL) >│ │ '2026-03-01 00:00:00': │ │ :TIMESTAMP) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ d │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Move the arithmetic to the constant side.** `d > DATE '2026-03-01' - 1` keeps the same rows as `date_add(d, INTERVAL 1 DAY) > TIMESTAMP '2026-03-01 00:00:00'`, and it's pushed down to VAST DataBase, so rows that don't match never leave storage. The constant side is computed once. Its plan has no `FILTER` step: ``` run(f"SELECT id FROM {TABLE} WHERE d > DATE '2026-03-01' - 1 ORDER BY id LIMIT 10") plan(f"SELECT id FROM {TABLE} WHERE d > DATE '2026-03-01' - 1") ``` ``` [(2,)] ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **For timestamps, subtract the interval from the constant:** `ts > TIMESTAMP '2026-03-01 00:00:00' - INTERVAL 1 HOUR` is pushed down, `date_add(ts, INTERVAL 1 HOUR) > ...` isn't ([-](/develop/docs/dev-database-reference-sql-functions-date-time-minus#make-it-faster)). ## Limitations and errors - **Write a negative interval in quotes, or negate it.** `INTERVAL -1 DAY` is a syntax error (`syntax error at or near "DAY"`). Write `INTERVAL '-1 day'` or `-INTERVAL 1 DAY`. - **Days only on a `DATE`.** A number of days works with a `DATE`; for a `TIMESTAMP` or a fraction of a day, add an `INTERVAL`. - **No time-zone support.** On a `TIMESTAMP WITH TIME ZONE` value, such as `now()`, `date_add` fails with `No function matches the given name and argument types '+(TIMESTAMP WITH TIME ZONE, INTERVAL)'`. Cast the value to `TIMESTAMP` first; see [time zones](/develop/docs/dev-database-reference-sql-functions-date-time-time-zones). - **Other SQL dialects' names and forms aren't available.** `dateadd` fails with `Scalar Function with name dateadd does not exist!`, and `date_add('day', 1, d)` with three arguments fails too. Use `date_add(d, INTERVAL 1 DAY)` or `d + INTERVAL 1 DAY`. ``` run("SELECT date_add(DATE '2026-03-01', INTERVAL -1 DAY)") run("SELECT date_add(DATE '2026-03-01', INTERVAL '-1 day'), date_add(DATE '2026-03-01', -INTERVAL 1 DAY)") run("SELECT date_add(now(), INTERVAL 1 DAY)") run("SELECT date_add(CAST(now() AS TIMESTAMP), INTERVAL 1 DAY) > CAST(now() AS TIMESTAMP)") run("SELECT dateadd('day', 1, DATE '2026-03-01')") ``` ``` InternalError: Parse query: 'SELECT date_add(DATE '2026-03-01', INTERVAL -1 DAY)' failed with: Parser Error: syntax error at or near "DAY" [(datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 2, 28, 0, 0))] 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: Catalog Error: Scalar Function with name dateadd does not exist! ``` ## Similar functions | Function or operator | Result for `DATE '2026-01-31'` and one month | | --- | --- | | [+](/develop/docs/dev-database-reference-sql-functions-date-time-plus), `add()` | The same: `d + INTERVAL 1 MONTH` is `2026-02-28 00:00:00` | | [-](/develop/docs/dev-database-reference-sql-functions-date-time-minus), `subtract()` | Goes back: `d - INTERVAL 1 MONTH`; the same as `date_add(d, -INTERVAL 1 MONTH)` | | [to_months](/develop/docs/dev-database-reference-sql-functions-date-time-to-months) and the other interval constructors | Build the interval from a number or a column: `d + to_months(1)` | | [time_bucket](/develop/docs/dev-database-reference-sql-functions-date-time-time-bucket), [date_trunc](/develop/docs/dev-database-reference-sql-functions-date-time-date-trunc) | Round a value down instead of moving it | ``` run("SELECT date_add(DATE '2026-01-31', INTERVAL 1 MONTH), DATE '2026-01-31' + INTERVAL 1 MONTH, " "add(DATE '2026-01-31', INTERVAL 1 MONTH), DATE '2026-01-31' + to_months(1), DATE '2026-01-31' + INTERVAL 30 DAY") run("SELECT DATE '2026-03-31' - INTERVAL 1 MONTH, date_add(DATE '2026-03-31', -INTERVAL 1 MONTH)") ``` ``` [(datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 2, 28, 0, 0), datetime.datetime(2026, 3, 2, 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. - [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.