--- title: "rpad" slug: "dev-database-reference-sql-functions-string-rpad" updated: 2026-10-30T18:18:56Z published: 2026-10-30T18:18:56Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-string-rpad" --- > ## 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. # rpad *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Trimming and padding](/develop/docs/dev-database-reference-sql-functions-string-trimming-and-padding) › Trimming and padding.* `rpad(s, n, fill)` returns `s` padded on the right with `fill`, repeated as often as needed, until it is `n` characters long. A string longer than `n` is cut to its first `n` characters. ## Syntax ``` rpad(s, n, fill) ``` | Argument | Type | Description | | --- | --- | --- | | `s` | `VARCHAR` | The string to pad. | | `n` | `INTEGER` | The length of the result, in characters (Unicode code points). | | `fill` | `VARCHAR` | The characters to add on the right, repeated and cut to fit. | **Returns:** `VARCHAR`. ## 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_string_rpad`. 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 parts with a code and a label. 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_string_rpad"' 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}.parts" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, code VARCHAR, label VARCHAR)") run(f"INSERT INTO {TABLE} VALUES " "(1, '42', 'Bolt'), " "(2, '7', 'Nut'), " "(3, '123456', 'Washer'), " "(4, 'caf\u00e9', 'Caf\u00e9 table'), " "(5, NULL, NULL)") ``` ``` [] [] [(5,)] ``` ## What it does `rpad` measures `s` in characters (Unicode code points), then: | Case | What happens | Example | Result | | --- | --- | --- | --- | | `s` is shorter than `n` | `fill` is added on the right, repeated and cut so the result is exactly `n` characters | `rpad('abc', 8, 'xyz')` | `'abcxyzxy'` | | `s` is `n` characters | `s` unchanged | `rpad('abc', 3, '*')` | `'abc'` | | `s` is longer than `n` | `s` is cut to its first `n` characters | `rpad('abc', 2, '*')` | `'ab'` | | `n` is 0 or negative | an empty string | `rpad('abc', -1, '*')` | `''` | A character is a code point, not what a reader sees: `e` followed by a combining accent (U+0301) counts as two, and so does a flag emoji. A cut can split such a pair, in `s` or in `fill`, and leave a bare `e`. All three arguments are required; for spaces, pass `' '` as the fill. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL` as any argument | `NULL` | | `rpad('', 3, '0')` | `'000'` | | `rpad('abc', 5, '')` (empty fill, padding needed) | Error: `Insufficient padding in RPAD.` | | `rpad('abc', 3, '')`, `rpad('abc', 2, '')` (no padding needed) | `'abc'`, `'ab'` | | `rpad('é', 3, '*')` (precomposed) | `'é**'` | | `rpad('e\u0301', 3, '*')` (e and a combining accent) | `e` and the accent, then `'*'` | | `rpad('abc', 4, 'e\u0301')` (the fill is cut after `e`) | `'abce'` | | `rpad('abc', '5', '*')` (`n` as a string) | `'abc**'` | | `rpad('abc', 2.5, '*')` | Error: `No function matches the given name and argument types 'rpad(STRING_LITERAL, DECIMAL(2,1), STRING_LITERAL)'` | | `rpad(42, 5, '0')` (a number as `s`) | Error: `No function matches the given name and argument types 'rpad(INTEGER_LITERAL, INTEGER_LITERAL, STRING_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-string-rpad#set-up-the-examples): ``` run("SELECT rpad(NULL, 5, '*'), rpad('abc', NULL, '*'), rpad('abc', 5, NULL), rpad('', 3, '0')") run("SELECT rpad('abc', 5, '')") run("SELECT rpad('abc', 3, ''), rpad('abc', 2, '')") run("SELECT rpad('\u00e9', 3, '*'), rpad('e\u0301', 3, '*'), rpad('abc', 4, 'e\u0301'), rpad('abc', '5', '*')") run("SELECT rpad('abc', 2.5, '*')") run("SELECT rpad(42, 5, '0')") ``` ``` [(None, None, None, '000')] OSError: Insufficient padding in RPAD. [('abc', 'ab')] [('é**', 'é*', 'abce', 'abc**')] InternalError: Binder Error: No function matches the given name and argument types 'rpad(STRING_LITERAL, DECIMAL(2,1), STRING_LITERAL)'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'rpad(INTEGER_LITERAL, INTEGER_LITERAL, STRING_LITERAL)'. You might need to add explicit type casts. ``` ## Examples Pad each label with dots to a fixed width of 12, as in a table of contents, and each code with spaces to six characters. The `|` shows where each value ends: ``` run(f"SELECT id, rpad(label, 12, '.') || '|', rpad(code, 6, ' ') || '|' FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'Bolt........|', '42 |'), (2, 'Nut.........|', '7 |'), (3, 'Washer......|', '123456|'), (4, 'Café table..|', 'café |'), (5, None, None)] ``` Cut every label to its first four characters. `rpad` cuts a longer string, so with a width shorter than every value it works like [left](/develop/docs/dev-database-reference-sql-functions-string-left), except that it also pads the shorter ones: ``` run(f"SELECT id, rpad(label, 4, '_'), left(label, 4) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'Bolt', 'Bolt'), (2, 'Nut_', 'Nut'), (3, 'Wash', 'Wash'), (4, 'Café', 'Café'), (5, None, None)] ``` ## 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 `rpad()` is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine pads each value it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes `rpad()` and keeps the rows that match. The plan of a padded comparison shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE rpad(code, 5, '0') = '42000'") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (rpad(code, 5, '0') = │ │ '42000') │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ code │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Compare the raw column.** `code = '42'` is pushed down to VAST DataBase, so rows that don't match never leave storage; `rpad(code, 5, '0') = '42000'` isn't. The plan has no `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE code = '42'") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **Pad at load time if you filter on the padded form.** Store the padded value in its own column, and compare that column with a constant. - **Combine it with a pushed-down condition.** In `id > 100 AND rpad(code, 5, '0') = '42000'`, `id > 100` is still evaluated in VAST DataBase, so `rpad()` runs only on the rows that pass it. ## Limitations and errors - **Strings only.** A number, a date, a boolean, a `BLOB` or a list as `s` fails with `No function matches the given name and argument types`; the error lists the one form, `rpad(VARCHAR, INTEGER, VARCHAR) -> VARCHAR`. Cast the value to `VARCHAR` first. - **The fill is required.** `rpad(s, n)` fails with `No function matches the given name and argument types 'rpad(STRING_LITERAL, INTEGER_LITERAL)'`. - **`n` is an `INTEGER`.** A decimal such as `2.5`, or a literal larger than an `INTEGER` such as `9223372036854775807`, fails with `No function matches the given name and argument types`. - **An empty fill fails when padding is needed,** with `Insufficient padding in RPAD.`. That includes a fill that comes from a column: one empty value fails the whole query. ``` run("SELECT rpad('a', 3)") run("SELECT rpad('a', 3, ' ') || '|', rpad(CAST(42 AS VARCHAR), 5, '0')") ``` ``` InternalError: Binder Error: No function matches the given name and argument types 'rpad(STRING_LITERAL, INTEGER_LITERAL)'. You might need to add explicit type casts. [('a |', '42000')] ``` ## Similar functions | Function | Pads | Result for `'42'` to five characters | Cuts a longer string | | --- | --- | --- | --- | | [lpad](/develop/docs/dev-database-reference-sql-functions-string-lpad)`('42', 5, '0')` | on the left | `'00042'` | yes, to the first `n` characters | | [printf](/develop/docs/dev-database-reference-sql-functions-string-printf)`('%-5s', '42')` | on the right, with spaces | `'42 '` | | | [printf](/develop/docs/dev-database-reference-sql-functions-string-printf)`('%05d', 42)` | a number, on the left with zeros | `'00042'` | no | | [left](/develop/docs/dev-database-reference-sql-functions-string-left)`('abcdef', 3)` | (cuts only) | | `'abc'` | ``` run("SELECT rpad('42', 5, '0'), lpad('42', 5, '0'), printf('%-5s|', '42'), printf('%05d', 42)") run("SELECT rpad('abcdef', 3, '*'), lpad('abcdef', 3, '*'), left('abcdef', 3), printf('%3s', 'abcdef')") ``` ``` [('42000', '00042', '42 |', '00042')] [('abc', 'abc', 'abc', 'abcdef')] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Trimming and padding](/develop/docs/dev-database-reference-sql-functions-string-trimming-and-padding): all the trimming and padding functions, including [trim](/develop/docs/dev-database-reference-sql-functions-string-trim), [ltrim](/develop/docs/dev-database-reference-sql-functions-string-ltrim) and [rtrim](/develop/docs/dev-database-reference-sql-functions-string-rtrim). - [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.