--- title: "generate_series (table function)" slug: "dev-database-reference-sql-functions-table-functions-generate-series" updated: 2026-10-30T18:18:46Z published: 2026-10-30T18:18:46Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-table-functions-generate-series" --- > ## 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. # generate_series (table function) *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Table functions](/develop/docs/dev-database-reference-sql-functions-table-functions) › Series of numbers and timestamps.* In `FROM`, `generate_series` returns rows: integers, or timestamps, from `start` to `stop` included, `step` apart. [range](/develop/docs/dev-database-reference-sql-functions-table-functions-range) is the same but stops before `stop`. In the `SELECT` list, `generate_series` returns the same values as one list instead: see [generate_series (list function)](/develop/docs/dev-database-reference-sql-functions-lists-generate-series). ## Syntax ``` generate_series(stop) generate_series(start, stop) generate_series(start, stop, step) generate_series(start_ts, stop_ts, interval) ``` | Argument | Type | Description | | --- | --- | --- | | `start` | `BIGINT` (any integer) | The first value. Leave it out to start at 0. | | `stop` | `BIGINT` (any integer) | The last value. It's returned if a step lands on it. | | `step` | `BIGINT` (any integer) | The distance between values; negative to count down. Default 1. | | `start_ts`, `stop_ts` | `TIMESTAMP` (a `DATE` is converted) | The first and the last timestamp. | | `interval` | `INTERVAL` | The distance between timestamps. Required for timestamps. | **Returns:** one column named `generate_series`, of type `BIGINT` for integers or `TIMESTAMP` for timestamps. Name it with an alias: `FROM generate_series(3) t(x)`. ## 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_table_functions_generate_series`. 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 an empty table of time slots, which an example fills from `generate_series`: ``` 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_table_functions_generate_series"' 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 estimated row count.""" 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).replace(BUCKET, "")) TABLE = f"{SCHEMA}.slots" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, at TIMESTAMP)") ``` ``` [] [] ``` ## What it does `generate_series` counts from `start` (0 if you leave it out) by `step` (1 if you leave it out), up to and including `stop` when a step lands on it. Each value is one row: | Call | Rows | | --- | --- | | `generate_series(3)` | `0`, `1`, `2`, `3` | | `generate_series(2, 5)` | `2`, `3`, `4`, `5` | | `generate_series(0, 10, 3)` | `0`, `3`, `6`, `9` (10 isn't a step from 0) | | `generate_series(10, 0, -3)` | `10`, `7`, `4`, `1` | Integer arguments of any size give `BIGINT` rows. To stop before `stop`, use [range](/develop/docs/dev-database-reference-sql-functions-table-functions-range). **Timestamps.** With two timestamps and an `INTERVAL`, `generate_series` returns the timestamps from `start_ts`, `interval` apart, up to and including `stop_ts`. A `DATE` is converted to a `TIMESTAMP` at midnight. A month step is added to the previous value: from January 31, `INTERVAL 1 MONTH` gives February 28, then March 28 and April 28. ## NULLs and edge cases | Input | Result | | --- | --- | | Any argument NULL | No rows | | `generate_series(0)` | One row, `0` | | `generate_series(2, 2)` | One row, `2` | | `generate_series(-2)`, `generate_series(5, 2)` | Error: `start is bigger than end, but increment is positive: cannot generate infinite series` | | `generate_series(0, 10, -1)` | Error: `start is smaller than end, but increment is negative: cannot generate infinite series` | | A step of 0, or `INTERVAL 0 DAY` | Error: `interval cannot be 0!` | | A decimal or a string, such as `generate_series(1, 3, 0.5)` or `generate_series('3')` | Error: `No function matches the given name and argument types` | | `generate_series(9223372036854775807, 9223372036854775807)` | One row, `9223372036854775807` | The same cases, as the cluster returns them. They use the helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-table-functions-generate-series#set-up-the-examples): ``` run("SELECT * FROM generate_series(1, NULL)") run("SELECT * FROM generate_series(0)") run("SELECT * FROM generate_series(2, 2)") run("SELECT * FROM generate_series(-2)") run("SELECT * FROM generate_series(5, 2)") run("SELECT * FROM generate_series(0, 10, -1)") run("SELECT * FROM generate_series(0, 10, 0)") run("SELECT * FROM generate_series(1, 3, 0.5)") run("SELECT * FROM generate_series('3')") run("SELECT * FROM generate_series(9223372036854775807, 9223372036854775807)") ``` ``` [] [(0,)] [(2,)] OSError: start is bigger than end, but increment is positive: cannot generate infinite series OSError: start is bigger than end, but increment is positive: cannot generate infinite series OSError: start is smaller than end, but increment is negative: cannot generate infinite series OSError: interval cannot be 0! InternalError: Binder Error: No function matches the given name and argument types 'generate_series(INTEGER, INTEGER, DECIMAL(2,1))'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'generate_series(VARCHAR)'. You might need to add explicit type casts. [(9223372036854775807,)] ``` ## Examples Name the column with an alias, and compute other columns from it: ``` run("SELECT x, x * x, 'id-' || x FROM generate_series(1, 4) t(x)") ``` ``` [(1, 1, 'id-1'), (2, 4, 'id-2'), (3, 9, 'id-3'), (4, 16, 'id-4')] ``` Every 20 minutes of an hour, both ends included, and every day of a short period: ``` run("SELECT * FROM generate_series(TIMESTAMP '2026-10-01 00:00', TIMESTAMP '2026-10-01 01:00', INTERVAL 20 MINUTE)") run("SELECT * FROM generate_series(DATE '2026-10-01', DATE '2026-10-04', INTERVAL 1 DAY)") ``` ``` [(datetime.datetime(2026, 10, 1, 0, 0),), (datetime.datetime(2026, 10, 1, 0, 20),), (datetime.datetime(2026, 10, 1, 0, 40),), (datetime.datetime(2026, 10, 1, 1, 0),)] [(datetime.datetime(2026, 10, 1, 0, 0),), (datetime.datetime(2026, 10, 2, 0, 0),), (datetime.datetime(2026, 10, 3, 0, 0),), (datetime.datetime(2026, 10, 4, 0, 0),)] ``` Fill a table with one slot per hour of a day, both midnights included (25 rows), numbering them with `row_number()`. `INSERT ... SELECT` creates the rows on the cluster: ``` run(f"INSERT INTO {TABLE} SELECT row_number() OVER (), ts " "FROM generate_series(TIMESTAMP '2026-10-01', TIMESTAMP '2026-10-02', INTERVAL 1 HOUR) t(ts)") run(f"SELECT count(*), min(id), max(id), min(at), max(at) FROM {TABLE}") ``` ``` [(25,)] [(25, 1, 25, datetime.datetime(2026, 10, 1, 0, 0), datetime.datetime(2026, 10, 2, 0, 0))] ``` An aggregate over a series, which has 100,001 rows because `stop` is included, and the first rows of a series too large to list: ``` run("SELECT count(*), min(x), max(x) FROM generate_series(100000) t(x)") run("SELECT * FROM generate_series(1000000000) t(x) LIMIT 3") ``` ``` [(100001, 0, 100000)] [(0,), (1,), (2,)] ``` ## How it runs in VAST The Query Engine runs on the cluster's CNodes. A query on a table starts with a scan in VAST DataBase (`VAST_SCAN`); `generate_series` replaces that scan. It produces its rows in the Query Engine, and the plan shows a `GENERATE_SERIES` step where `VAST_SCAN` would be. Nothing is read from storage, so a `WHERE` condition on the rows runs in a `FILTER` step above it: ``` plan("SELECT x FROM generate_series(10) t(x) WHERE x > 5") ``` ``` ┌───────────────────────────┐ │ FILTER │ │ ──────────────────── │ │ (x > 5) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ GENERATE_SERIES │ │ ──────────────────── │ │ Function: │ │ GENERATE_SERIES │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Put the bounds in the arguments, not in `WHERE`.** `generate_series(5, 10)` generates six rows; `generate_series(10)` with `WHERE x >= 5` generates eleven, and the `FILTER` step drops five of them. - **Generate test data on the cluster.** One `INSERT INTO t SELECT ... FROM generate_series(...)` statement creates the rows in the Query Engine instead of sending them from your client. - **Use the step for regular samples.** `generate_series(0, 1000, 10)` gives every tenth value directly, instead of `WHERE x % 10 = 0` on a longer series. ## Limitations and errors - **`ORDER BY` needs a `LIMIT`.** Without one it fails with `The operator 'ORDER_BY' type=1 is currently not supported for this usage.` - **One source per query.** `generate_series` can't be joined with a table or with another table function: a join fails with `The operator 'HASH_JOIN' type=32 is currently not supported.`, two table functions in `FROM` with `The operator 'CROSS_PRODUCT' type=33 is currently not supported.`, and `generate_series(col)` with a table's column with `The operator 'HASH_GROUP_BY' type=9 is currently not supported.` `UNION ALL` of two series works. - **No `GROUP BY`.** It fails with `The operator 'HASH_GROUP_BY' type=9 is currently not supported.` An aggregate over the whole series works. - **No time-zone timestamps.** `TIMESTAMP WITH TIME ZONE` bounds fail with `No function matches the given name and argument types 'generate_series(TIMESTAMP WITH TIME ZONE, TIMESTAMP WITH TIME ZONE, INTERVAL)'`. Use `TIMESTAMP` values. `TIME` values aren't accepted either. - **Timestamps need an interval.** `generate_series(ts1, ts2)` fails; add the step, such as `INTERVAL 1 DAY`. ``` run("SELECT x FROM generate_series(5) t(x) ORDER BY x DESC") run("SELECT x FROM generate_series(5) t(x) ORDER BY x DESC LIMIT 3") run(f"SELECT id, x FROM {TABLE} JOIN generate_series(3) r(x) ON id = x") run("SELECT x % 3 AS k, count(*) FROM generate_series(10) t(x) GROUP BY k ORDER BY k LIMIT 20") run("SELECT * FROM generate_series(TIMESTAMPTZ '2026-10-09 12:34:56+00', TIMESTAMPTZ '2026-10-11 12:34:56+00', INTERVAL 1 DAY)") run("SELECT * FROM generate_series(TIMESTAMP '2026-10-09 12:34:56', TIMESTAMP '2026-10-11 12:34:56', INTERVAL 1 DAY)") run("SELECT * FROM generate_series(TIMESTAMP '2026-10-01', TIMESTAMP '2026-10-04')") ``` ``` InternalError: The operator 'ORDER_BY' type=1 is currently not supported for this usage. [(5,), (4,), (3,)] InternalError: The operator 'HASH_JOIN' type=32 is currently not supported. InternalError: The operator 'HASH_GROUP_BY' type=9 is currently not supported. InternalError: Binder Error: No function matches the given name and argument types 'generate_series(TIMESTAMP WITH TIME ZONE, TIMESTAMP WITH TIME ZONE, INTERVAL)'. You might need to add explicit type casts. [(datetime.datetime(2026, 10, 9, 12, 34, 56),), (datetime.datetime(2026, 10, 10, 12, 34, 56),), (datetime.datetime(2026, 10, 11, 12, 34, 56),)] InternalError: Binder Error: No function matches the given name and argument types 'generate_series(TIMESTAMP, TIMESTAMP)'. You might need to add explicit type casts. ``` ## Similar functions | Function | Includes `stop` | `(1, 4)` | `(0)` | | --- | --- | --- | --- | | `generate_series` in `FROM` | yes | rows `1`, `2`, `3`, `4` | one row, `0` | | [range](/develop/docs/dev-database-reference-sql-functions-table-functions-range) in `FROM` | no | rows `1`, `2`, `3` | no rows | | [generate_series (list function)](/develop/docs/dev-database-reference-sql-functions-lists-generate-series), in the `SELECT` list | yes | the list `[1, 2, 3, 4]` | `[0]` | ``` run("SELECT * FROM generate_series(1, 4)") run("SELECT * FROM range(1, 4)") run("SELECT generate_series(1, 4), generate_series(0)") ``` ``` [(1,), (2,), (3,), (4,)] [(1,), (2,), (3,)] [([1, 2, 3, 4], [0])] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Table functions](/develop/docs/dev-database-reference-sql-functions-table-functions): all the table functions. - [range](/develop/docs/dev-database-reference-sql-functions-table-functions-range), [unnest](/develop/docs/dev-database-reference-sql-functions-table-functions-unnest) and [generate_series (list function)](/develop/docs/dev-database-reference-sql-functions-lists-generate-series). - [SELECT](/develop/docs/dev-database-reference-sql-select) and [INSERT](/develop/docs/dev-database-reference-sql-insert). - [EXPLAIN](/develop/docs/dev-database-reference-sql-explain): how to read a plan.