--- title: "normalized_interval" slug: "dev-database-reference-sql-functions-date-time-normalized-interval" updated: 2026-10-30T18:19:01Z published: 2026-10-30T18:19:01Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-date-time-normalized-interval" --- > ## 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. # normalized_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.* Returns the same interval with whole days carried out of its time and whole months carried out of its days, counting 24 hours to a day and 30 days to a month. ## Syntax ``` normalized_interval(i) ``` | Argument | Type | Description | | --- | --- | --- | | `i` | `INTERVAL` | The interval to normalize. A string is converted to an `INTERVAL`. | **Returns:** `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_normalized_interval`. 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. A table can't have an `INTERVAL` column, so the examples build intervals from two timestamps: `closed - opened` is an interval of days and time. This block connects, defines the `run()` and `plan()` helpers, and creates a table of five support tickets. 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_normalized_interval"' 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}.tickets" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, opened TIMESTAMP, closed TIMESTAMP)") run(f"INSERT INTO {TABLE} VALUES " "(1, TIMESTAMP '2026-01-01 00:00:00', TIMESTAMP '2026-02-10 06:00:00'), " "(2, TIMESTAMP '2026-03-01 08:00:00', TIMESTAMP '2026-03-02 20:00:00'), " "(3, TIMESTAMP '2026-03-01 08:00:00', TIMESTAMP '2026-03-01 08:00:59'), " "(4, NULL, NULL), " "(5, TIMESTAMP '2026-03-10 00:00:00', TIMESTAMP '2026-01-29 00:00:00')") ``` ``` [] [] [(5,)] ``` ## What it does An interval has three fields: months, days, and a time (stored in nanoseconds). Arithmetic can leave more than a day in the time field or more than a month in the days field: the difference of two timestamps, for example, is in days and time and never has months. `normalized_interval` carries the excess over, counting **24 hours to a day and 30 days to a month**: - `INTERVAL '40 days 30 hours'` becomes 1 month 11 days 6 hours. - `INTERVAL '1 year 400 days'` becomes 25 months 10 days (a year is 12 months). - `INTERVAL '29 days 24 hours'` becomes 1 month. Fields with opposite signs are combined: `INTERVAL '1 month -45 days'` becomes -15 days, and `INTERVAL '-1 day 25 hours'` becomes 1 hour. A negative interval stays negative in every field: `INTERVAL '-40 days'` becomes -1 month -10 days. The interval keeps its length as the Query Engine measures it: `normalized_interval(INTERVAL 1 MONTH)` equals `normalized_interval(INTERVAL 30 DAY)`. Normalizing changes what the part functions read from it: `hour(INTERVAL '36 hours')` is `36`, and `hour(normalized_interval(INTERVAL '36 hours'))` is `12`. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL` | `NULL` | | `INTERVAL 59 SECOND` | Unchanged: 59 seconds | | `INTERVAL '1000000 hours'` | 1388 months 26 days 16 hours | | `'40 days'` (a string) | 1 month 10 days | | `'abc'` | Error: `Could not convert string 'abc' to INTERVAL` | | A `DATE`, `TIMESTAMP`, `TIME` or number | Error: `No function matches the given name and argument types`, for example `'normalized_interval(DATE)'` | The same cases, as the cluster returns them, with the examples from [What it does](/develop/docs/dev-database-reference-sql-functions-date-time-normalized-interval#what-it-does). They use the helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-date-time-normalized-interval#set-up-the-examples): ``` run("SELECT normalized_interval(INTERVAL '40 days 30 hours'), normalized_interval(INTERVAL '1 year 400 days'), " "normalized_interval(INTERVAL '29 days 24 hours')") run("SELECT normalized_interval(INTERVAL '1 month -45 days'), normalized_interval(INTERVAL '-1 day 25 hours'), " "normalized_interval(INTERVAL '-40 days')") run("SELECT normalized_interval(INTERVAL 1 MONTH) = normalized_interval(INTERVAL 30 DAY), " "hour(INTERVAL '36 hours'), hour(normalized_interval(INTERVAL '36 hours'))") run("SELECT normalized_interval(NULL), normalized_interval(INTERVAL 59 SECOND), " "normalized_interval(INTERVAL '1000000 hours'), normalized_interval('40 days')") run("SELECT normalized_interval('abc')") run("SELECT normalized_interval(DATE '2026-01-01')") ``` ``` [(MonthDayNano(months=1, days=11, nanoseconds=21600000000000), MonthDayNano(months=25, days=10, nanoseconds=0), MonthDayNano(months=1, days=0, nanoseconds=0))] [(MonthDayNano(months=0, days=-15, nanoseconds=0), MonthDayNano(months=0, days=0, nanoseconds=3600000000000), MonthDayNano(months=-1, days=-10, nanoseconds=0))] [(True, 36, 12)] [(None, MonthDayNano(months=0, days=0, nanoseconds=59000000000), MonthDayNano(months=1388, days=26, nanoseconds=57600000000000), MonthDayNano(months=1, days=10, nanoseconds=0))] OSError: Could not convert string 'abc' to INTERVAL InternalError: Binder Error: No function matches the given name and argument types 'normalized_interval(DATE)'. You might need to add explicit type casts. ``` ## Examples How long each ticket stayed open, as the difference of the timestamps and normalized. Ticket 1 was open 40 days 6 hours, which normalizes to 1 month 10 days 6 hours; ticket 5 was closed before it was opened, so its interval is negative: ``` run(f"SELECT id, closed - opened, normalized_interval(closed - opened) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, MonthDayNano(months=0, days=40, nanoseconds=21600000000000), MonthDayNano(months=1, days=10, nanoseconds=21600000000000)), (2, MonthDayNano(months=0, days=1, nanoseconds=43200000000000), MonthDayNano(months=0, days=1, nanoseconds=43200000000000)), (3, MonthDayNano(months=0, days=0, nanoseconds=59000000000), MonthDayNano(months=0, days=0, nanoseconds=59000000000)), (4, None, None), (5, MonthDayNano(months=0, days=-40, nanoseconds=0), MonthDayNano(months=-1, days=-10, nanoseconds=0))] ``` The months, days and hours of each normalized interval, with [month](/develop/docs/dev-database-reference-sql-functions-date-time-month), [day](/develop/docs/dev-database-reference-sql-functions-date-time-day) and [hour](/develop/docs/dev-database-reference-sql-functions-date-time-hour): ``` run(f"SELECT id, month(normalized_interval(closed - opened)), day(normalized_interval(closed - opened)), " f"hour(normalized_interval(closed - opened)) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 1, 10, 6), (2, 0, 1, 12), (3, 0, 0, 0), (4, None, None, None), (5, -1, -10, 0)] ``` ## 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 columns, so `normalized_interval()` is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the columns and the Query Engine computes the interval and normalizes it for each row it returns. - **In `WHERE`,** the scan sends the columns for every row, and a `FILTER` step in the Query Engine computes `normalized_interval()` and keeps the rows that match. No rows are skipped in storage. The plan of a filter on the normalized interval shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE month(normalized_interval(closed - opened)) >= 1") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #2 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ("month" │ │ (normalized_interval( │ │ (closed - opened))) >= 1) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ closed │ │ opened │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Don't normalize to compare.** Intervals compare by length, with 30 days to a month and 24 hours to a day, so `INTERVAL '40 days 30 hours' = INTERVAL '1 month 11 days 6 hours'` is already true. Write `closed - opened > INTERVAL 30 DAY` rather than a test on the normalized fields. - **Normalize in the `SELECT` list,** where it doesn't stop a filter from being pushed down. - **Store the duration if you filter on it often.** Compute it when you write the rows, for example as whole seconds in a `BIGINT` column: a comparison of that column with a constant is pushed down to VAST DataBase. ``` run("SELECT INTERVAL '40 days 30 hours' = INTERVAL '1 month 11 days 6 hours'") run(f"SELECT id FROM {TABLE} WHERE closed - opened > INTERVAL 30 DAY ORDER BY id LIMIT 10") ``` ``` [(True,)] [(1,)] ``` ## Limitations and errors - **A month is 30 days.** `normalized_interval` doesn't know which months the interval spans: 40 days is always 1 month 10 days, whether it ran through February or through July. - **Intervals only.** A date, timestamp, time or number fails with `No function matches the given name and argument types`. A string must be a valid interval: `'abc'` fails with `Could not convert string 'abc' to INTERVAL`. - **Other SQL dialects' names aren't available.** `justify_interval` fails with `Scalar Function with name justify_interval does not exist!`; use `normalized_interval`. ``` run("SELECT justify_interval(INTERVAL '40 days')") ``` ``` InternalError: Catalog Error: Scalar Function with name justify_interval does not exist! ``` ## Similar functions | Function | Does | Result for `INTERVAL '40 days 30 hours'` | | --- | --- | --- | | `normalized_interval` | Carries hours into days and days into months | 1 month 11 days 6 hours | | [date_trunc](/develop/docs/dev-database-reference-sql-functions-date-time-date-trunc) with `'day'` | Drops the time field, without carrying it into days | 40 days | | [epoch](/develop/docs/dev-database-reference-sql-functions-date-time-epoch) | The whole length in seconds, as a `DOUBLE` | `3564000.0` | ``` run("SELECT normalized_interval(INTERVAL '40 days 30 hours'), date_trunc('day', INTERVAL '40 days 30 hours'), " "epoch(INTERVAL '40 days 30 hours')") ``` ``` [(MonthDayNano(months=1, days=11, nanoseconds=21600000000000), MonthDayNano(months=0, days=40, nanoseconds=0), 3564000.0)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [/ (divide an interval)](/develop/docs/dev-database-reference-sql-functions-date-time-divide) and [* (multiply)](/develop/docs/dev-database-reference-sql-functions-date-time-multiply): interval arithmetic, field by field. - [- (minus)](/develop/docs/dev-database-reference-sql-functions-date-time-minus): the difference of two timestamps. - [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).