--- title: "repeat" slug: "dev-database-reference-sql-functions-string-repeat" updated: 2026-10-30T18:18:56Z published: 2026-10-30T18:18:56Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-string-repeat" --- > ## 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. # repeat *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Text basics](/develop/docs/dev-database-reference-sql-functions-string-text-basics) › Changing text.* Returns a string, a `BLOB` or a list repeated a number of times, joined end to end. `repeat` has no aliases. ## Syntax ``` repeat(s, count) ``` | Argument | Type | Description | | --- | --- | --- | | `s` | `VARCHAR`, `BLOB` or a list | The value to repeat. | | `count` | `BIGINT` | How many times to repeat it. An integer literal such as `2`, or an `INTEGER` column, works. 0 or less gives an empty value of the type of `s`. | **Returns:** the type of `s`: `VARCHAR`, `BLOB`, or a list of the same element type. **Aliases:** none. ## 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_repeat`. 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 four tasks in an outline: each has a depth, a list of tags and a marker byte string. The last row 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_repeat"' 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}.tasks" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, title VARCHAR, depth BIGINT, tags VARCHAR[], marker BLOB)") run(f"INSERT INTO {TABLE} VALUES " "(1, 'Plan the release', 0, ['planning'], '\\xAA'::BLOB), " "(2, 'Write the notes', 1, ['docs', 'release'], '\\x00\\xFF'::BLOB), " "(3, 'Review the notes', 2, [], ''::BLOB), " "(4, NULL, NULL, NULL, NULL)") ``` ``` [] [] [(4,)] ``` ## What it does `repeat` joins `count` copies of `s` end to end. It has one form for each type of `s`: | Type of `s` | Example | Result | | --- | --- | --- | | `VARCHAR` | `repeat('Hello', 2)` | `'HelloHello'` | | `BLOB` | `repeat('\xAA'::BLOB, 2)` | `b'\xaa\xaa'` (two bytes) | | List | `repeat([1, 2], 2)` | `[1, 2, 1, 2]` | | List | `repeat(['a', 'b'], 2)` | `['a', 'b', 'a', 'b']` | On a list, `repeat` repeats the elements, not the list: the result is one flat list, not a list of lists. A `count` of 0 or less returns an empty value of the same type: `''`, an empty `BLOB` or an empty list (`repeat([1, 2], 0)` and `repeat([1], -1)` both return `[]`). An empty list or an empty `BLOB` stays empty. The result can be large: `repeat('ab', 1000000)` returns a string of 2,000,000 characters. `repeat` used in a `FROM` clause is a different function with the same name: a table function that returns a value in a number of rows. See [Table functions](/develop/docs/dev-database-reference-sql-functions-table-functions-repeat). ## NULLs and edge cases | Input | Call | Result | | --- | --- | --- | | `s` is `NULL` | `repeat(NULL, 2)` | `NULL` | | `count` is `NULL` | `repeat('ab', NULL)` | `NULL` | | `''` (empty string) | `repeat('', 2)`, `repeat('', 5)` | `''`, whatever the count | | `count` is 0 | `repeat('ab', 0)` | `''` | | `count` is negative | `repeat('ab', -1)` | `''` | | Type of an untyped `NULL` | `typeof(repeat(NULL, 2))` | `'BLOB'`: an untyped `NULL` picks the `BLOB` form | | Type of a `VARCHAR` `NULL` | `typeof(repeat(CAST(NULL AS VARCHAR), 2))` | `'VARCHAR'` | | A `BLOB` | `repeat('\xAA'::BLOB, 2)` | `b'\xaa\xaa'` | | A list of integers | `repeat([1, 2], 2)` | `[1, 2, 1, 2]` | | A list of strings | `repeat(['a', 'b'], 2)` | `['a', 'b', 'a', 'b']` | | A large count | `length(repeat('ab', 1000000))` | `2000000` | | `count` is a decimal, such as `2.6` | `repeat('ab', 2.6)` | Error: `No function matches the given name and argument types` | | A number as `s` | `repeat(123, 2)` | Error: `No function matches the given name and argument types` | 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-string-repeat#set-up-the-examples): ``` run("SELECT repeat(NULL, 2), repeat('ab', NULL), repeat('', 2), repeat('', 5), repeat('ab', 0), repeat('ab', -1)") run("SELECT typeof(repeat(NULL, 2)), typeof(repeat(CAST(NULL AS VARCHAR), 2))") run("SELECT repeat('\\xAA'::BLOB, 2), repeat([1, 2], 2), repeat(['a', 'b'], 2), length(repeat('ab', 1000000))") run("SELECT repeat('ab', 2.6)") run("SELECT repeat(123, 2)") ``` ``` [(None, None, '', '', '', '')] [('BLOB', 'VARCHAR')] [(b'\xaa\xaa', [1, 2, 1, 2], ['a', 'b', 'a', 'b'], 2000000)] InternalError: Binder Error: No function matches the given name and argument types 'repeat(STRING_LITERAL, DECIMAL(2,1))'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'repeat(INTEGER_LITERAL, INTEGER_LITERAL)'. You might need to add explicit type casts. ``` ## Examples Indent each title by its depth, two dots per level. A depth of 0 gives an empty indent, and the row with no values gives `NULL`: ``` run(f"SELECT id, repeat('..', depth) || title FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'Plan the release'), (2, '..Write the notes'), (3, '....Review the notes'), (4, None)] ``` Repeat a list and a `BLOB` column. Each result keeps the type of its column: a list of `VARCHAR` and a `BLOB`: ``` run(f"SELECT id, repeat(tags, 2), repeat(marker, 3) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, ['planning', 'planning'], b'\xaa\xaa\xaa'), (2, ['docs', 'release', 'docs', 'release'], b'\x00\xff\x00\xff\x00\xff'), (3, [], b''), (4, None, None)] ``` Keep the tasks whose indent is two levels deep. [Make it faster](/develop/docs/dev-database-reference-sql-functions-string-repeat#make-it-faster) shows a cheaper way to write this filter: ``` run(f"SELECT id, title FROM {TABLE} WHERE repeat('..', depth) = '....' ORDER BY id LIMIT 10") ``` ``` [(3, 'Review the notes')] ``` ## 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 `repeat()` is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the columns and the Query Engine computes `repeat()` for each row it returns. - **In `WHERE`,** the scan sends the columns for every row, and a `FILTER` step in the Query Engine computes `repeat()` 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 repeat('..', depth) = '....'") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (repeat('..', depth) = '..│ │ ..') │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ depth │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Filter on the count, not on the repeated value.** `repeat('..', depth) = '....'` keeps the same rows as `depth = 2`, but only the second is a comparison of a raw column with a constant, which is pushed down to VAST DataBase, so rows that don't match never leave storage. Its plan has no `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE depth = 2") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **Mind the size of the result.** The result is `count` times the size of `s`, for every row. A large count on a long column makes every returned row that much larger. ## Limitations and errors - **Strings, `BLOB` values and lists only.** A number, a date or a boolean fails with `No function matches the given name and argument types`. Cast it to `VARCHAR` first. - **An integer count.** A decimal count, such as `2.6`, fails with `No function matches the given name and argument types`. Cast it to `BIGINT` first; the cast rounds, so `CAST(2.6 AS BIGINT)` repeats 3 times. - **An untyped `NULL` gives a `BLOB`.** `repeat(NULL, 2)` uses the `BLOB` form. Cast the `NULL` if the type matters: `repeat(CAST(NULL AS VARCHAR), 2)`. - **`space` isn't available.** `space(n)` fails with `Scalar Function with name space does not exist!`. Use `repeat(' ', n)`. ``` run("SELECT repeat('ab', CAST(2.6 AS BIGINT)), repeat(' ', 3) || '|'") run("SELECT space(3)") ``` ``` [('ababab', ' |')] InternalError: Catalog Error: Scalar Function with name space does not exist! ``` ## Similar functions | Function | What it repeats | Call | Result | | --- | --- | --- | --- | | `repeat` on a string | the string | `repeat('ab', 2)` | `'abab'` | | `repeat` on a list | the elements of the list, in one flat list | `repeat([1, 2], 2)` | `[1, 2, 1, 2]` | | `repeat` on a `BLOB` | the bytes | `repeat('\xAA'::BLOB, 2)` | `b'\xaa\xaa'` | | [repeat (table function)](/develop/docs/dev-database-reference-sql-functions-table-functions-repeat) | a value, in rows | `SELECT * FROM repeat(42, 2)` | rows that hold `42` | The list and `BLOB` forms are also described in [List functions](/develop/docs/dev-database-reference-sql-functions-lists-and-structs) and [Binary functions](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-repeat). To pad a string to a given length, use [lpad and rpad](/develop/docs/dev-database-reference-sql-functions-string-lpad). [replace](/develop/docs/dev-database-reference-sql-functions-string-replace), [translate](/develop/docs/dev-database-reference-sql-functions-string-translate) and [reverse](/develop/docs/dev-database-reference-sql-functions-string-reverse) are the other functions that change text. ``` run("SELECT repeat('ab', 2), repeat([1, 2], 2), repeat('\\xAA'::BLOB, 2)") run("SELECT * FROM repeat(42, 2)") ``` ``` [('abab', [1, 2, 1, 2], b'\xaa\xaa')] [(42,), (42,)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Text basics](/develop/docs/dev-database-reference-sql-functions-string-text-basics): all the text functions. - [Table functions](/develop/docs/dev-database-reference-sql-functions-table-functions-repeat): `repeat` in `FROM`. - [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.