--- title: "lower" slug: "dev-database-reference-sql-functions-string-lower" updated: 2026-10-30T18:18:56Z published: 2026-10-30T18:18:56Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-string-lower" --- > ## 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. # lower *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) › Case.* Returns a string with every upper-case letter converted to lower case, including accented, Greek and other non-ASCII letters. `lcase` is the same function. ## Syntax ``` lower(s) lcase(s) ``` | Argument | Type | Description | | --- | --- | --- | | `s` | `VARCHAR` | The string to convert. | **Returns:** `VARCHAR`. **Aliases:** `lcase`. ## 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_lower`. 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 accounts. `email` holds the address as the user typed it; `email_lower` holds the same address in lower case, written by the application when it stored the row. 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_lower"' 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}.accounts" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, email VARCHAR, email_lower VARCHAR, country VARCHAR)") run(f"INSERT INTO {TABLE} VALUES " "(1, 'Ada@Example.com', 'ada@example.com', 'GB'), " "(2, 'GRACE.HOPPER@EXAMPLE.COM', 'grace.hopper@example.com', 'US'), " "(3, 'JOSÉ@Example.COM', 'josé@example.com', 'CU'), " "(4, NULL, NULL, NULL)") ``` ``` [] [] [(4,)] ``` ## What it does `lower` maps each upper-case letter to its lower-case form, one character at a time, and leaves everything else (lower-case letters, digits, punctuation, spaces, emoji, combining marks) unchanged. It covers Unicode letters, not only ASCII: | Input | Result | Note | | --- | --- | --- | | `'ABC123!'` | `'abc123!'` | Digits and punctuation are unchanged. | | `'ÀÉÎ'` | `'àéî'` | Accented capitals become accented small letters. | | `'ẞ'` (capital sharp s, U+1E9E) | `'ß'` | | | `'İ'` (capital I with dot above, U+0130) | `'i'` | A plain ASCII `i`, without a dot mark. | | `'ΣΑΣ'` | `'σασ'` | Every Σ becomes σ, also at the end of a word, where Greek spelling uses ς. | | `'Dž'` (the title-case digraph, U+01C5) | `'dž'` (U+01C6) | | | `'e\u0301 🇫🇷'` (e and a combining accent, a flag) | `'e\u0301 🇫🇷'`, unchanged | The combining accent stays a separate code point: the result isn't normalized to é (U+00E9). | `lower` takes no language argument, so the mapping is the same for all text: `İ` becomes a plain `i`. If you need language-specific rules, such as Turkish, where `İ` pairs with `i` and `I` with `ı`, apply them in your code. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL` | `NULL` | | `''` (empty string) | `''` | | `'ẞ'` | `'ß'` | | `'İ'` | `'i'` | | `'ΣΑΣ'` | `'σασ'` | | `'ÀÉÎ'` | `'àéî'` | | `'ABC123!'` | `'abc123!'` | | `lcase('A')` | `'a'` | | `'e\u0301 🇫🇷'` | unchanged: `length` of the result is still `5` | | A `BLOB` | Error: `No function matches the given name and argument types 'lower(BLOB)'` | | A list, such as `['a', 'b']` | Error: `No function matches the given name and argument types 'lower(VARCHAR[])'` | | A number, date or boolean | Error: `No function matches the given name and argument types`, for example `'lower(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-string-lower#set-up-the-examples): ``` run("SELECT lower(NULL), lower(''), lower('ẞ'), lower('İ'), lower('ΣΑΣ'), lower('ÀÉÎ'), lower('ABC123!'), lcase('A')") run("SELECT lower('e\u0301 🇫🇷'), length(lower('e\u0301 🇫🇷'))") run("SELECT lower('\\xAA'::BLOB)") run("SELECT lower(['a', 'b'])") run("SELECT lower(123)") ``` ``` [(None, '', 'ß', 'i', 'σασ', 'àéî', 'abc123!', 'a')] [('é 🇫🇷', 5)] InternalError: Binder Error: No function matches the given name and argument types 'lower(BLOB)'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'lower(VARCHAR[])'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'lower(INTEGER_LITERAL)'. You might need to add explicit type casts. ``` ## Examples Each address in lower case, with `lcase` on the country code. `É` in row 3 becomes `é`: ``` run(f"SELECT id, lower(email), lcase(country) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'ada@example.com', 'gb'), (2, 'grace.hopper@example.com', 'us'), (3, 'josé@example.com', 'cu'), (4, None, None)] ``` Look an address up without regard to how it was typed: ``` run(f"SELECT id, email FROM {TABLE} WHERE lower(email) = 'grace.hopper@example.com' ORDER BY id LIMIT 10") ``` ``` [(2, 'GRACE.HOPPER@EXAMPLE.COM')] ``` ## 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 `lower()` of a column is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine computes `lower()` for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes `lower()` and keeps the rows that match. No rows are skipped in storage. `lower()` of a constant is different: it's computed before the scan, so `email_lower = lower('Grace.Hopper@Example.com')` is a comparison of the raw column with a constant, and is pushed down. The plan of the lookup example shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE lower(email) = 'grace.hopper@example.com'") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (lower(email) = 'grace │ │ .hopper@example.com') │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ email │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Store a lower-case copy and compare it with a lower-case constant.** If you look up values without regard to case, write a lower-case column when you store the rows, and apply `lower()` to the value you search for instead of the column. The comparison is pushed down to VAST DataBase, so rows that don't match never leave storage. The plan has no `FILTER` step: ``` run(f"SELECT id, email FROM {TABLE} WHERE email_lower = lower('Grace.Hopper@Example.com') ORDER BY id LIMIT 10") plan(f"SELECT id FROM {TABLE} WHERE email_lower = lower('Grace.Hopper@Example.com')") ``` ``` [(2, 'GRACE.HOPPER@EXAMPLE.COM')] ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **`COLLATE nocase` is `lower()` too.** `email COLLATE nocase = '...'` is planned as a `lower(email)` filter, so it isn't faster; see [COLLATE nocase and noaccent](/develop/docs/dev-database-reference-sql-functions-string-collate). - **Combine it with a pushed-down condition.** In `country = 'US' AND lower(email) = '...'`, `country = 'US'` is still evaluated in VAST DataBase, so `lower()` runs only on the rows that pass it. ## Limitations and errors - **Strings only.** A number, a date, a boolean, a list or a `BLOB` fails with `No function matches the given name and argument types`; the error lists `lower(VARCHAR)` as the only form. - **No language rules.** `lower` takes no language argument; see [What it does](/develop/docs/dev-database-reference-sql-functions-string-lower#what-it-does). - **No title case.** `initcap` isn't available: it fails with `Scalar Function with name initcap does not exist!`. Capitalize words in your code. ``` run("SELECT initcap('ada lovelace')") ``` ``` InternalError: Catalog Error: Scalar Function with name initcap does not exist! ``` ## Similar functions | Function | What it does | Result for `'Straße'` (`lower` gives `'straße'`) | | --- | --- | --- | | `lcase` | the same function as `lower` | `'straße'` | | [upper](/develop/docs/dev-database-reference-sql-functions-string-upper) (also `ucase`) | converts to upper case | `'STRAẞE'` | | [COLLATE nocase](/develop/docs/dev-database-reference-sql-functions-string-collate) | compares two strings as `lower()` of each (in a plan, the constant side is already lower-cased) | `'Straße' COLLATE nocase = 'STRAẞE'` is `true` | | [strip_accents](/develop/docs/dev-database-reference-sql-functions-string-strip-accents) | removes accents, keeps case | see its page | | [ILIKE](/develop/docs/dev-database-reference-sql-functions-operators-and-predicates#like-and-ilike) | pattern match without regard to case | see its page | ``` run("SELECT lower('Straße'), lcase('Straße'), upper('Straße'), 'Straße' COLLATE nocase = 'STRAẞE'") ``` ``` [('straße', 'straße', 'STRAẞE', True)] ``` 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. - [upper](/develop/docs/dev-database-reference-sql-functions-string-upper) and [COLLATE nocase and noaccent](/develop/docs/dev-database-reference-sql-functions-string-collate). - [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.