--- title: "julian" slug: "dev-database-reference-sql-functions-date-time-julian" updated: 2026-10-30T18:19:01Z published: 2026-10-30T18:19:01Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-date-time-julian" --- > ## 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. # julian *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) › Names and calendar.* Returns the Julian day number of a date, as a `DOUBLE`. For a timestamp, the time of day is added as a fraction of a day. ## Syntax ``` julian(value) ``` | Argument | Type | Description | | --- | --- | --- | | `value` | `DATE` or `TIMESTAMP` (also `TIMESTAMP_NS`, `TIMESTAMP_MS`, `TIMESTAMP_S`) | The date or timestamp to convert. | **Returns:** `DOUBLE`. **Same as:** `date_part('julian', value)` and `extract(julian FROM value)`; see [date_part](/develop/docs/dev-database-reference-sql-functions-date-time-date-part). ## 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_julian`. 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 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_julian"' 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, 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 `julian` counts days from day 0, 24 November 4714 BC: `julian(DATE '2000-01-01')` is `2451545.0`, and `julian(DATE '1970-01-01')` is `2440588.0`. On a `DATE`, the result is a whole number. On a timestamp, the time of day is added as a fraction of a day that starts at midnight: `julian(TIMESTAMP '1970-01-01 12:00:00')` is `2440588.5`. This is half a day more than the astronomical Julian date, which starts each day at noon: `epoch(v) / 86400 + 2440587.5` gives that value. The result is a `DOUBLE`, so the fraction isn't exact to the microsecond: row 5's timestamp, one microsecond before 1970, gives `2440588.0`. Use [epoch_us](/develop/docs/dev-database-reference-sql-functions-date-time-epoch-us) when you need exact microseconds. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL`, or a NULL value (row 4) | `NULL` | | `DATE 'infinity'`, `TIMESTAMP '-infinity'` | `NULL` | | `DATE '0001-01-01'` | `1721426.0` | | `DATE '9999-12-31'` | `5373484.0` | | 44 BC: `CAST('0044-03-15 (BC)' AS DATE)` | `1705428.0` | | Day 0: `CAST('4714-11-24 (BC)' AS DATE)` | `0.0` | | `TIMESTAMP '1970-01-01 12:00:00'` | `2440588.5` | | A `TIME` | Error: `No function matches the given name and argument types 'julian(TIME)'` | | An `INTERVAL` | Error: `No function matches the given name and argument types 'julian(INTERVAL)'` | | A string | Error: `Could not choose a best candidate function`; cast it to `DATE` or `TIMESTAMP` first | | A number, boolean, `BLOB` or list | Error: `No function matches the given name and argument types`, for example `'julian(INTEGER_LITERAL)'` | 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-julian#set-up-the-examples): ``` run(f"SELECT id, julian(ts) FROM {TABLE} WHERE id = 4") run("SELECT julian(NULL), julian(DATE 'infinity'), julian(TIMESTAMP '-infinity')") run("SELECT julian(DATE '0001-01-01'), julian(DATE '9999-12-31'), julian(CAST('0044-03-15 (BC)' AS DATE)), " "julian(CAST('4714-11-24 (BC)' AS DATE)), julian(TIMESTAMP '1970-01-01 12:00:00')") run("SELECT julian(TIME '13:45:30')") run("SELECT julian(INTERVAL '1 day')") run("SELECT julian('2024-02-29')") run("SELECT julian(123)") ``` ``` [(4, None)] [(None, None, None)] [(1721426.0, 5373484.0, 1705428.0, 0.0, 2440588.5)] InternalError: Binder Error: No function matches the given name and argument types 'julian(TIME)'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'julian(INTERVAL)'. You might need to add explicit type casts. InternalError: Binder Error: Could not choose a best candidate function for the function call "julian(STRING_LITERAL)". In order to select one, please add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'julian(INTEGER_LITERAL)'. You might need to add explicit type casts. ``` ## Examples The Julian day of each event's date and timestamp: ``` run(f"SELECT id, julian(d), julian(ts) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 2461100.0, 2461100.96875), (2, 2461101.0, 2461101.354688929), (3, 2460675.0, 2460675.5), (4, None, None), (5, 2440587.0, 2440588.0)] ``` The number of days between two dates is the difference of their Julian days: ``` run("SELECT julian(DATE '2026-03-01') - julian(DATE '2024-02-29')") ``` ``` [(731.0,)] ``` Keep only the events after Julian day 2461000 (20 November 2025). This works, but [Make it faster](/develop/docs/dev-database-reference-sql-functions-date-time-julian#make-it-faster) has a faster way to write it: ``` run(f"SELECT id FROM {TABLE} WHERE julian(d) > 2461000 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 a function of a column, so `julian()` is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine computes `julian()` for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes `julian()` 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 julian(d) > 2461000") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (julian(d) > 2461000.0) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ d │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Compare the raw column with a date, not `julian()` with a number.** `d > DATE '2025-11-20'` returns the same rows as `julian(d) > 2461000`, and it's pushed down to VAST DataBase, so rows that don't match never leave storage. The plan has no `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE d > DATE '2025-11-20'") run(f"SELECT id FROM {TABLE} WHERE d > DATE '2025-11-20' ORDER BY id LIMIT 10") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ [(1,), (2,)] ``` - **Use `julian()` in the `SELECT` list,** where it doesn't stop a filter from being pushed down. ## Limitations and errors - **No time-zone support.** On a `TIMESTAMP WITH TIME ZONE` value, such as `now()`, `julian` fails with an `Extension Autoloading Error`. Cast the value to `TIMESTAMP` first: `julian(CAST(now() AS TIMESTAMP))`. See [time zones](/develop/docs/dev-database-reference-sql-functions-date-time-time-zones). - **Dates and timestamps only.** A `TIME` or an `INTERVAL` has no day number and fails with `No function matches the given name and argument types`. - **One argument.** `julian(ts, ts)` fails with `No function matches the given name and argument types 'julian(TIMESTAMP, TIMESTAMP)'`. ``` run(f"SELECT julian(ts, ts) FROM {TABLE} LIMIT 1") ``` ``` InternalError: Binder Error: No function matches the given name and argument types 'julian(TIMESTAMP, TIMESTAMP)'. You might need to add explicit type casts. ``` ## Similar functions | Function | Returns | Result for `DATE '2024-02-29'` (`julian` gives `2460370.0`) | | --- | --- | --- | | [date_part](/develop/docs/dev-database-reference-sql-functions-date-time-date-part) with `'julian'` (or `'jd'`), `extract(julian FROM ...)` | The same value | `2460370.0` | | [epoch](/develop/docs/dev-database-reference-sql-functions-date-time-epoch) | Seconds since 1970-01-01; `epoch(v) / 86400 + 2440588` is the same day count | `2460370.0` | | [dayofyear](/develop/docs/dev-database-reference-sql-functions-date-time-dayofyear) | The day within the year | `60` | | [date_diff](/develop/docs/dev-database-reference-sql-functions-date-time-date-diff) with `'day'` | Whole days between two values | (two arguments) | ``` run("SELECT julian(DATE '2024-02-29'), date_part('julian', DATE '2024-02-29'), extract(julian FROM DATE '2024-02-29'), " "epoch(DATE '2024-02-29') / 86400 + 2440588, dayofyear(DATE '2024-02-29')") ``` ``` [(2460370.0, 2460370.0, 2460370.0, 2460370.0, 60)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [date_part](/develop/docs/dev-database-reference-sql-functions-date-time-date-part): any part of a value, by name. - [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.