--- title: "list_contains" slug: "dev-database-reference-sql-functions-lists-list-contains" updated: 2026-10-30T18:19:06Z published: 2026-10-30T18:19:06Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-lists-list-contains" --- > ## 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. # list_contains *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [List, struct and map functions](/develop/docs/dev-database-reference-sql-functions-lists-and-structs) › Search a list.* Returns true if a list has an element equal to a value, false if it doesn't. `list_has`, `array_contains`, `array_has` and `contains` (with a list) are the same function. ## Syntax ``` list_contains(list, element) list_has(list, element) array_contains(list, element) array_has(list, element) contains(list, element) ``` | Argument | Type | Description | | --- | --- | --- | | `list` | a list of any element type | The list to search. | | `element` | the list's element type, or one that converts to it | The value to look for. | **Returns:** `BOOLEAN`. **Aliases:** `list_has`, `array_contains`, `array_has`, and `contains` when its first argument is a list. ## 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_lists_list_contains`. 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 articles, each with a list of tags and a list of ratings. Article 2 has NULL elements, article 3 has empty lists, and 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_lists_list_contains"' 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}.articles" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, tags VARCHAR[], ratings BIGINT[])") run(f"INSERT INTO {TABLE} VALUES " "(1, ['db', 'sql'], [4, 5, 5]), " "(2, ['vector', NULL], [3, NULL, 1]), " "(3, [], []), " "(4, NULL, NULL)") ``` ``` [] [] [(4,)] ``` ## What it does `list_contains` is true if any element of `list` equals `element`: - **Exact, typed comparison.** Strings must match exactly, so the match is case-sensitive (`'A'` doesn't match `'a'`), and an `é` written as one code point (U+00E9) doesn't match an `e` followed by a combining accent (U+0301). Numbers of different types compare by value: `2.0` matches `2` in an `INTEGER[]`, `2.5` doesn't. - **Whole elements, not substrings.** `list_contains(['abc'], 'b')` is false. To search inside a string, use [contains](/develop/docs/dev-database-reference-sql-functions-string-contains) with a string. - **Nested lists** are searched one level down: `list_contains([[1, 2], [3]], [1, 2])` is true. - **`NaN` matches `NaN`,** and `-0.0` matches `0.0`. ## NULLs and edge cases | Input | Result | | --- | --- | | A NULL list: `list_contains(NULL, 1)` | `NULL` | | A NULL `element`: `list_contains([1, 2], NULL)` | `NULL` | | NULL in both: `list_contains([1, NULL], NULL)` | `NULL`: NULL never matches | | `list_contains([1, NULL], 2)` | `false` | | `list_contains([], 1)` (empty list) | `false` | | `list_contains([1, 2], 2.0)` | `true` | | `list_contains([1, 2], 2.5)` | `false` | | `list_contains(['a', 'b'], 'A')` | `false` | | `list_contains(['\u00e9'], 'e\u0301')` | `false` | | `list_contains(['NaN'::DOUBLE, 1.0], 'NaN'::DOUBLE)` | `true` | | `list_contains([-0.0], 0.0)` | `true` | | `list_contains([[1, 2], [3]], [1, 2])` | `true` | | `list_contains([1, 2], 'a')` (a value of another type) | Error: `list_contains: Cannot match element of type 'VARCHAR' in a list of type 'INTEGER[]' - an explicit cast is required` | 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-lists-list-contains#set-up-the-examples): ``` run("SELECT list_contains(NULL, 1), list_contains([1, 2], NULL), list_contains([1, NULL], NULL), " "list_contains([1, NULL], 2), list_contains([], 1)") run("SELECT list_contains([1, 2], 2.0), list_contains([1, 2], 2.5), list_contains(['a', 'b'], 'A'), " "list_contains(['\u00e9'], 'e\u0301')") run("SELECT list_contains(['NaN'::DOUBLE, 1.0], 'NaN'::DOUBLE), list_contains([-0.0], 0.0), " "list_contains([[1, 2], [3]], [1, 2])") run("SELECT list_contains([1, 2], 'a')") ``` ``` [(None, None, None, False, False)] [(True, False, False, False)] [(True, True, True)] InternalError: Binder Error: list_contains: Cannot match element of type 'VARCHAR' in a list of type 'INTEGER[]' - an explicit cast is required ``` ## Examples Which articles are tagged `sql`, and which have a rating of 5. Article 2 has a NULL tag, but no `sql` tag, so the answer is false; the NULL lists of article 4 give NULL: ``` run(f"SELECT id, list_contains(tags, 'sql'), list_has(ratings, 5) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, True, True), (2, False, False), (3, False, False), (4, None, None)] ``` Keep only the articles with a rating of 1. The aliases return the same rows: ``` run(f"SELECT id FROM {TABLE} WHERE list_contains(ratings, 1) ORDER BY id LIMIT 10") run(f"SELECT id FROM {TABLE} WHERE array_has(ratings, 1) AND contains(ratings, 1) ORDER BY id LIMIT 10") ``` ``` [(2,)] [(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`). The scan reads list columns whole, and every condition on a list, `list_contains()` included, runs in the Query Engine: - **In the `SELECT` list,** the scan sends the list column and the Query Engine searches it for each row it returns. - **In `WHERE`,** the scan sends the list for every row, and a `FILTER` step in the Query Engine searches it 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 list_contains(ratings, 1)") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ list_contains(ratings, 1) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ ratings │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Pair it with a pushed-down condition.** A comparison of a plain column with a constant, such as `id > 1`, is evaluated in VAST DataBase, so the rows it rules out never reach the `FILTER` step. The plan shows which conditions are left in the `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE id > 1 AND list_contains(ratings, 1)") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #0 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ list_contains(ratings, 1) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ id │ │ ratings │ │ │ └───────────────────────────┘ ``` - **Keep values you filter on often outside the list.** If most queries ask whether one particular tag is present, store it in its own column when you write the rows, such as `has_sql BIGINT` set to 1 or 0: `has_sql = 1` is pushed down, `list_contains(tags, 'sql')` isn't. - **Test several values in one call.** To ask whether any of several values is present, [list_has_any](/develop/docs/dev-database-reference-sql-functions-lists-list-has-any) takes them as one list. ## Limitations and errors - **The first argument must be a list.** A number, string, date, boolean or `BLOB` fails with `No function matches the given name and argument types`, for example `'list_contains(INTEGER_LITERAL, INTEGER_LITERAL)'`. The error lists the one form: `list_contains(ANY[], ANY) -> BOOLEAN`. - **The value must match the element type.** A string in a list of numbers, or a number in a list of strings, fails with `Cannot match element of type ... - an explicit cast is required`. So does a scalar in a nested list: `list_contains([[1, 2], [3]], 1)`. Cast the value, or flatten the list with [flatten](/develop/docs/dev-database-reference-sql-functions-lists-flatten). - **`contains` has other forms.** `contains` also takes a string (is one string inside another) and a map (is a key in the map), so `contains(NULL, 1)` fails with `Could not choose a best candidate function for the function call`. Use `list_contains`. - **NULL can't be found.** `list_contains(l, NULL)` is NULL, even when the list holds a NULL element. To test for NULL elements, count them with [list_filter](/develop/docs/dev-database-reference-sql-functions-lists-list-filter): `len(list_filter(l, x -> x IS NULL)) > 0`. ``` run("SELECT list_contains([[1, 2], [3]], 1)") run("SELECT contains(NULL, 1)") run("SELECT contains('abc', 'b'), contains([1, 2], 2), contains(MAP {'a': 1}, 'a'), contains(['abc'], 'b')") run("SELECT len(list_filter(l, x -> x IS NULL)) > 0 FROM (SELECT [3, 1, NULL, 3, 10] AS l)") ``` ``` InternalError: Binder Error: list_contains: Cannot match element of type 'INTEGER' in a list of type 'INTEGER[][]' - an explicit cast is required InternalError: Binder Error: Could not choose a best candidate function for the function call "contains("NULL", INTEGER_LITERAL)". In order to select one, please add explicit type casts. [(True, True, True, False)] [(True,)] ``` ## Similar functions | Function | Answers | Result for `[3, 1, NULL, 3, 10]` | | --- | --- | --- | | `list_contains(l, 3)` | is 3 an element? | `true` | | [list_position](/develop/docs/dev-database-reference-sql-functions-lists-list-position)`(l, 3)` | where is the first 3? | `1` | | [list_has_any](/develop/docs/dev-database-reference-sql-functions-lists-list-has-any)`(l, [3, 99])` | is any of these an element? | `true` | | [list_has_all](/develop/docs/dev-database-reference-sql-functions-lists-list-has-all)`(l, [3, 10])` | are all of these elements? | `true` | | [list_filter](/develop/docs/dev-database-reference-sql-functions-lists-list-filter) with `len(...) > 0` | is any element `= 3`, by a lambda you write | `true` | ``` run("SELECT list_contains(l, 3), list_position(l, 3), list_has_any(l, [3, 99]), list_has_all(l, [3, 10]), " "len(list_filter(l, x -> x = 3)) > 0 FROM (SELECT [3, 1, NULL, 3, 10] AS l)") ``` ``` [(True, 1, True, True, True)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [List, struct and map functions](/develop/docs/dev-database-reference-sql-functions-lists-and-structs): all the list functions. - [map_contains](/develop/docs/dev-database-reference-sql-functions-maps-map-contains): the map form of `contains`. - [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.