--- title: "typeof" slug: "dev-database-reference-sql-functions-conditional-and-cast-typeof" updated: 2026-10-30T18:18:46Z published: 2026-10-30T18:18:46Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-conditional-and-cast-typeof" --- > ## 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. # typeof *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Conditional and conversion functions](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast) › Converting types.* Returns the name of the type of an expression, as text: `'INTEGER'`, `'DECIMAL(2,1)'`, `'VARCHAR[]'`. Use it to check what type a column, a literal or a calculation has before you compare or convert it. ## Syntax ``` typeof(x) ``` | Argument | Type | Description | | --- | --- | --- | | `x` | any | The expression whose type you want. | **Returns:** `VARCHAR`, the type name in uppercase, with its parameters: `DECIMAL(10,2)`, `INTEGER[2]`, `STRUCT(a INTEGER)`. ## 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_conditional_and_cast_typeof`. 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 with one column of each of several types and two rows. The second 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_conditional_and_cast_typeof"' 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}.samples" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, name VARCHAR, n INTEGER, price DOUBLE, " "amount DECIMAL(10,2), ok BOOLEAN, day DATE, at TIMESTAMP, u UUID, tags BIGINT[], data BLOB)") run(f"INSERT INTO {TABLE} VALUES " "(1, 'ada', 42, 2.5, 2.50, true, DATE '2026-10-16', TIMESTAMP '2026-10-16 12:00:00', " "'6f1c2a4e-8b3d-4c1a-9e2f-0a1b2c3d4e5f', [1, 2], '\\x68\\x69'::BLOB), " "(2, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL)") ``` ``` [] [] [(2,)] ``` ## What it does `typeof(x)` returns the type the VAST Query Engine gives `x`. It looks only at the type, not the value: - **A column has its declared type on every row,** including rows where it's NULL. - **A literal's type follows its form.** `1` is an `INTEGER`, `2147483648` a `BIGINT`, `1.5` a `DECIMAL(2,1)` (not a `DOUBLE`), `1e3` a `DOUBLE`, and `'a'` a `VARCHAR`. - **Calculations have the type the operator returns.** `1 + 1.5` is a `DECIMAL(12,1)`, `1 + 1.5::DOUBLE` a `DOUBLE`, `7 / 2` a `DOUBLE`, and the sum of two `TINYINT` values a `TINYINT`. - **Parameters are part of the name:** `DECIMAL(10,2)`, `INTEGER[2]` for a fixed-size array, `STRUCT(a INTEGER)`, `MAP(VARCHAR, INTEGER)`, `ENUM('a', 'b')`. A length on `VARCHAR` isn't kept: `typeof('abc'::VARCHAR(1))` is `'VARCHAR'`. ## NULLs and edge cases | Input | Result | | --- | --- | | `typeof(NULL)` | `'"NULL"'`: the text `NULL` in double quotes | | `typeof(CAST(NULL AS INTEGER))` | `'INTEGER'` | | `typeof(1)`, `typeof(2147483648)`, `typeof(9223372036854775808)` | `'INTEGER'`, `'BIGINT'`, `'HUGEINT'` | | `typeof(1.5)`, `typeof(1e3)`, `typeof(1.5::DOUBLE)` | `'DECIMAL(2,1)'`, `'DOUBLE'`, `'DOUBLE'` | | `typeof(true)`, `typeof(DATE '2026-10-16')`, `typeof(TIMESTAMP '2026-10-16')`, `typeof(INTERVAL 1 DAY)` | `'BOOLEAN'`, `'DATE'`, `'TIMESTAMP'`, `'INTERVAL'` | | `typeof([1, 2])`, `typeof([1, 2]::INTEGER[2])` | `'INTEGER[]'`, `'INTEGER[2]'` | | `typeof({'a': 1})`, `typeof(MAP {'a': 1})` | `'STRUCT(a INTEGER)'`, `'MAP(VARCHAR, INTEGER)'` | | `typeof('a'::BLOB)`, `typeof('1'::BIT)`, `typeof('{}'::JSON)`, `typeof(gen_random_uuid())` | `'BLOB'`, `'BIT'`, `'JSON'`, `'UUID'` | | `typeof(typeof(1))` | `'VARCHAR'` | | `typeof()`, `typeof(1, 2)` | Error: `No function matches the given name and argument types` | The same cases, as the cluster returns them. They use the helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast-typeof#set-up-the-examples): ``` run("SELECT typeof(NULL), typeof(CAST(NULL AS INTEGER)), typeof(1), typeof(2147483648), " "typeof(9223372036854775808), typeof(1.5), typeof(1e3), typeof(1.5::DOUBLE)") run("SELECT typeof(true), typeof(DATE '2026-10-16'), typeof(TIMESTAMP '2026-10-16'), typeof(INTERVAL 1 DAY), " "typeof([1, 2]), typeof([1, 2]::INTEGER[2]), typeof({'a': 1}), typeof(MAP {'a': 1})") run("SELECT typeof('a'::BLOB), typeof('1'::BIT), typeof('{}'::JSON), typeof(gen_random_uuid()), " "typeof(typeof(1))") run("SELECT typeof(1, 2)") ``` ``` [('"NULL"', 'INTEGER', 'INTEGER', 'BIGINT', 'HUGEINT', 'DECIMAL(2,1)', 'DOUBLE', 'DOUBLE')] [('BOOLEAN', 'DATE', 'TIMESTAMP', 'INTERVAL', 'INTEGER[]', 'INTEGER[2]', 'STRUCT(a INTEGER)', 'MAP(VARCHAR, INTEGER)')] [('BLOB', 'BIT', 'JSON', 'UUID', 'VARCHAR')] InternalError: Binder Error: No function matches the given name and argument types 'typeof(INTEGER_LITERAL, INTEGER_LITERAL)'. You might need to add explicit type casts. ``` ## Examples The type of each column. It's the same on the row where every value is NULL: ``` run(f"SELECT id, typeof(name), typeof(n), typeof(price), typeof(amount), typeof(ok), typeof(day), typeof(at), " f"typeof(u), typeof(tags), typeof(data) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'VARCHAR', 'INTEGER', 'DOUBLE', 'DECIMAL(10,2)', 'BOOLEAN', 'DATE', 'TIMESTAMP', 'UUID', 'BIGINT[]', 'BLOB'), (2, 'VARCHAR', 'INTEGER', 'DOUBLE', 'DECIMAL(10,2)', 'BOOLEAN', 'DATE', 'TIMESTAMP', 'UUID', 'BIGINT[]', 'BLOB')] ``` Check the type of a calculation before you compare it. Adding a `DECIMAL` literal keeps the result a `DECIMAL`; a `DOUBLE` makes it a `DOUBLE`; dividing two integers with `/` gives a `DOUBLE`: ``` run("SELECT typeof(1 + 1.5), typeof(1 + 1.5::DOUBLE), typeof(7 / 2), typeof(1::TINYINT + 1::TINYINT), " "typeof('abc'::VARCHAR(1)), typeof('a'::ENUM('a', 'b'))") ``` ``` [('DECIMAL(12,1)', 'DOUBLE', 'DOUBLE', 'TINYINT', 'VARCHAR', "ENUM('a', 'b')")] ``` ## 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`). `typeof()` depends only on types, which the Query Engine knows when it plans the query, so it never needs the column's values: - **In `WHERE`,** a condition such as `typeof(n) = 'INTEGER'` is decided before the scan. The plan has no `FILTER` step for it. - **In the `SELECT` list,** it gives the same text for every row. The plan of a condition on `typeof()`: ``` plan(f"SELECT id FROM {TABLE} WHERE typeof(n) = 'INTEGER'") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Use it while you write a query, not in production filters.** A condition on `typeof()` is true for every row or for none, so it doesn't select rows; it only helps you see which type a comparison or a conversion works on. ## Limitations and errors - **Exactly one argument.** `typeof()` and `typeof(1, 2)` fail with `No function matches the given name and argument types`. - **`typeof(NULL)` includes quotes.** It returns `"NULL"`, with the double quotes. A NULL of a known type, such as `CAST(NULL AS INTEGER)` or a NULL in a column, gives that type instead. - **The names are uppercase and exact.** Compare with `'INTEGER'`, not `'integer'`, and include parameters: a `DECIMAL(10,2)` column gives `'DECIMAL(10,2)'`, not `'DECIMAL'`. Use `starts_with(typeof(x), 'DECIMAL')` to match any precision. ``` run("SELECT typeof(NULL) = 'NULL', typeof(NULL) = '\"NULL\"', length(typeof(NULL))") run(f"SELECT typeof(amount) = 'DECIMAL', starts_with(typeof(amount), 'DECIMAL') FROM {TABLE} LIMIT 1") ``` ``` [(False, True, 6)] [(False, True)] ``` ## Similar functions | Function | Returns | For `1` | For `1.5` | | --- | --- | --- | --- | | `typeof(x)` | the type name, uppercase | `'INTEGER'` | `'DECIMAL(2,1)'` | | [pg_typeof](/develop/docs/dev-database-reference-sql-functions-utility-pg-typeof)`(x)` | the type name, lowercase | `'integer'` | `'decimal(2,1)'` | | [can_cast_implicitly](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast-can-cast-implicitly)`(x, y)` | whether the type of `x` converts to the type of `y` without a cast | | | | [CAST](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast-cast)`(x AS type)` | `x` converted to another type | | | ``` run("SELECT typeof(1), pg_typeof(1), typeof(1.5), pg_typeof(1.5), pg_typeof(1) = typeof(1), " "can_cast_implicitly(1::INTEGER, 1::BIGINT), typeof(CAST(1 AS DOUBLE))") ``` ``` [('INTEGER', 'integer', 'DECIMAL(2,1)', 'decimal(2,1)', False, True, 'DOUBLE')] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Conditional and conversion functions](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast): all the conversion functions. - [Data types in SQL](/develop/docs/dev-database-reference-sql-data-types): the types and their names. - [EXPLAIN](/develop/docs/dev-database-reference-sql-explain): how to read a plan.