--- title: "isfinite" slug: "dev-database-reference-sql-functions-numeric-isfinite" updated: 2026-10-30T18:18:51Z published: 2026-10-30T18:18:51Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-numeric-isfinite" --- > ## 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. # isfinite *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Numeric and math functions](/develop/docs/dev-database-reference-sql-functions-numeric) › Floating-point values.* Returns `true` if `x` is an ordinary number, and `false` if it's `inf`, `-inf` or NaN. It also takes a date or timestamp, and is `false` for the special values `'infinity'` and `'-infinity'`. ## Syntax ``` isfinite(x) ``` | Argument | Type | Description | | --- | --- | --- | | `x` | `DOUBLE`, `FLOAT`, `DATE`, `TIMESTAMP` or `TIMESTAMP WITH TIME ZONE` | The value to test. An integer or `DECIMAL` literal is accepted, and is always finite. | **Returns:** `BOOLEAN`. ## 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_numeric_isfinite`. 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 seven measurements: ordinary values, both infinities, NaN, negative zero and, in row 6, no value: ``` 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_numeric_isfinite"' 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}.measurements" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, x DOUBLE)") run(f"INSERT INTO {TABLE} VALUES " "(1, 2.5), (2, 'inf'::DOUBLE), (3, '-inf'::DOUBLE), (4, 'nan'::DOUBLE), " "(5, '-0.0'::DOUBLE), (6, NULL), (7, 1.0)") ``` ``` [] [] [(7,)] ``` ## What it does `isfinite(x)` is `true` for every number you can do ordinary arithmetic with, negative zero included, and `false` for the three special floating-point values: `inf`, `-inf` and NaN. It's `NOT isinf(x) AND NOT isnan(x)` in one call. NULL gives NULL, so a `WHERE isfinite(x)` condition also drops the rows with no value. Use it to keep only usable values before you aggregate: a sum of a column that holds `inf` and `-inf` is NaN, and `max()` of a column that holds NaN is NaN. For a `DATE` or `TIMESTAMP`, `isfinite()` is `false` for `'infinity'` and `'-infinity'` and `true` for an ordinary date. The [date and time version](/develop/docs/dev-database-reference-sql-functions-date-time-isfinite) has the details. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL`, `NULL::FLOAT` | `NULL` | | `1.0::DOUBLE`, `-0.0::DOUBLE`, `1::FLOAT` | `true` | | `1`, `2.45`, `9223372036854775807` (integer and `DECIMAL` literals) | `true` | | `'inf'::DOUBLE`, `'-inf'::DOUBLE`, `'nan'::DOUBLE` | `false` | | `'nan'::FLOAT`, `'inf'::FLOAT` | `false` | | `0 / 0`, `1 / 0`, `-1 / 0`, `1e308 * 10` | `false` | | `DATE '2026-10-16'` | `true` | | `'infinity'::DATE`, `'infinity'::TIMESTAMP` | `false` | | `'nan'` or any other string literal | Error: `Could not choose a best candidate function for the function call "isfinite(STRING_LITERAL)"`; cast it: `'nan'::DOUBLE` | | A `BLOB`, boolean, list or interval | Error: `No function matches the given name and argument types`, for example `'isfinite(BOOLEAN)'` | 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-numeric-isfinite#set-up-the-examples): ``` run("SELECT isfinite(NULL), isfinite(NULL::FLOAT), isfinite(1.0::DOUBLE), isfinite(-0.0::DOUBLE), isfinite(1::FLOAT)") run("SELECT isfinite(1), isfinite(2.45), isfinite(9223372036854775807), typeof(isfinite(1))") run("SELECT isfinite('inf'::DOUBLE), isfinite('-inf'::DOUBLE), isfinite('nan'::DOUBLE), " "isfinite('nan'::FLOAT), isfinite('inf'::FLOAT)") run("SELECT isfinite(0 / 0), isfinite(1 / 0), isfinite(-1 / 0), isfinite(1e308 * 10)") run("SELECT isfinite(DATE '2026-10-16'), isfinite('infinity'::DATE), isfinite('infinity'::TIMESTAMP)") run("SELECT isfinite('nan')") run("SELECT isfinite(true)") ``` ``` [(None, None, True, True, True)] [(True, True, True, 'BOOLEAN')] [(False, False, False, False, False)] [(False, False, False, False)] [(True, False, False)] InternalError: Binder Error: Could not choose a best candidate function for the function call "isfinite(STRING_LITERAL)". In order to select one, please add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'isfinite(BOOLEAN)'. You might need to add explicit type casts. ``` ## Examples Test each measurement. Row 6 has no value, so its result is NULL: ``` run(f"SELECT id, x, isfinite(x) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 2.5, True), (2, inf, False), (3, -inf, False), (4, nan, False), (5, -0.0, True), (6, None, None), (7, 1.0, True)] ``` Aggregate all the values, then only the finite ones. The first sum and maximum are NaN; with `WHERE isfinite(x)`, `inf`, `-inf` and NaN are left out: ``` run(f"SELECT min(x), max(x), sum(x), count(x) FROM {TABLE}") run(f"SELECT min(x), max(x), sum(x), count(x) FROM {TABLE} WHERE isfinite(x)") ``` ``` [(-inf, nan, nan, 6)] [(-0.0, 2.5, 3.5, 3)] ``` ## 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 `isfinite()` is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine computes `isfinite()` for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes `isfinite()` and keeps the rows that match. The plan of the aggregate with `WHERE isfinite(x)` shows the `FILTER` step above the scan: ``` plan(f"SELECT sum(x) FROM {TABLE} WHERE isfinite(x)") ``` ``` ┌───────────────────────────┐ │ UNGROUPED_AGGREGATE │ │ ──────────────────── │ │ Aggregates: sum(x) │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ isfinite(x) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: x │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Store NULL for a missing or undefined result, not `inf` or NaN.** Aggregates skip NULLs (`count(x)` above doesn't count row 6), so you don't need an `isfinite()` filter at all. ## Limitations and errors - **A string literal must be cast.** `isfinite('nan')` fails with `Could not choose a best candidate function for the function call "isfinite(STRING_LITERAL)"`, because the literal could be a number, a date or a timestamp. Write `isfinite('nan'::DOUBLE)`. - **Numbers, dates and timestamps only.** A `BLOB`, boolean, list or interval fails with `No function matches the given name and argument types`. - **`is_finite()` isn't available.** It fails with `Scalar Function with name is_finite does not exist!`; use `isfinite()`: ``` run("SELECT is_finite(1.0)") ``` ``` InternalError: Catalog Error: Scalar Function with name is_finite does not exist! ``` ## Similar functions | Function | `nan` | `inf` | `-inf` | `-0.0` | `1.0` | `NULL` | | --- | --- | --- | --- | --- | --- | --- | | [isnan](/develop/docs/dev-database-reference-sql-functions-numeric-isnan)`(x)` | `true` | `false` | `false` | `false` | `false` | `NULL` | | [isinf](/develop/docs/dev-database-reference-sql-functions-numeric-isinf)`(x)` | `false` | `true` | `true` | `false` | `false` | `NULL` | | `isfinite(x)` | `false` | `false` | `false` | `true` | `true` | `NULL` | | [signbit](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-signbit)`(x)` | `false` | `false` | `true` | `true` | `false` | `NULL` | ``` run("SELECT x, isnan(x), isinf(x), isfinite(x), signbit(x) FROM (VALUES ('nan'::DOUBLE), ('inf'::DOUBLE), " "('-inf'::DOUBLE), (-0.0::DOUBLE), (1.0::DOUBLE), (NULL::DOUBLE)) v(x)") ``` ``` [(nan, True, False, False, False), (inf, False, True, False, False), (-inf, False, True, False, True), (-0.0, False, False, True, True), (1.0, False, False, True, False), (None, None, None, None, None)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Numeric and math functions](/develop/docs/dev-database-reference-sql-functions-numeric#floating-point-values): isnan, isinf and isfinite. - [isfinite for dates and timestamps](/develop/docs/dev-database-reference-sql-functions-date-time-isfinite). - [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.