--- title: "pow" slug: "dev-database-reference-sql-functions-numeric-pow" updated: 2026-10-30T18:18:51Z published: 2026-10-30T18:18:51Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-numeric-pow" --- > ## 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. # pow *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) › Powers and logarithms.* Returns `x` raised to the power `y`, as a `DOUBLE`. `power` is the same function, and `x ** y` and `x ^ y` are operators for it. ## Syntax ``` pow(x, y) power(x, y) x ** y x ^ y ``` | Argument | Type | Description | | --- | --- | --- | | `x` | `DOUBLE` (any number) | The base. | | `y` | `DOUBLE` (any number) | The exponent. | **Returns:** `DOUBLE`, whatever the argument types: `pow(2, 2)` on two integers is `4.0`. **Aliases:** `power`. The operators `**` and `^` do the same. ## 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_pow`. 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 three savings accounts: an amount, a yearly rate of return and a number of years. 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_numeric_pow"' 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}.savings" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, amount DOUBLE, rate DOUBLE, years INTEGER)") run(f"INSERT INTO {TABLE} VALUES " "(1, 1000.0, 0.05, 10), " "(2, 2500.0, 0.03, 5), " "(3, 800.0, -0.1, 3), " "(4, NULL, NULL, NULL)") ``` ``` [] [] [(4,)] ``` ## What it does `pow(x, y)` computes xy in double-precision floating point: `pow(2, 10)` is `1024.0`, `pow(2, 0.5)` is the square root of 2, and `pow(2, -1)` is `0.5`. Integer, `DECIMAL` and `FLOAT` arguments are converted to `DOUBLE`, and so is a string that holds a number: `pow('12', 2)` is `144.0`. A result with no real value, or one too big or too small for a `DOUBLE`, isn't an error. You get a special value instead: - **Infinity** (`inf`) when the result is too big, as for `pow(2, 1024)`, and for `pow(0, -1)`. - **Zero** when it's too small: `pow(2, -1075)` is `0.0`. - **NaN** (not a number) for a negative base with a fractional exponent: `pow(-8, 1.0 / 3)` and `pow(-1, 0.5)` are `nan`. A negative base with a whole exponent works: `pow(-8, 3)` is `-512.0`. For the cube root of a negative number, use [cbrt](/develop/docs/dev-database-reference-sql-functions-numeric-cbrt). Because the result is a `DOUBLE`, a large power isn't exact: `pow(3, 40)` is `1.2157665459056929e+19`, not the exact integer, and `pow(9007199254740993, 1)` is `9007199254740992.0`. ### The ** and ^ operators `x ** y` and `x ^ y` return the same as `pow(x, y)`. Two rules differ from ordinary maths notation, so use parentheses: - **A minus sign binds first.** `-2 ** 2` is `(-2) ** 2`, which is `4.0`. Write `-(2 ** 2)` to negate the power. - **A chain is evaluated from the left.** `2 ** 3 ** 2` is `(2 ** 3) ** 2`, which is `64.0`, not 29. Write `2 ** (3 ** 2)` for that. Multiplication binds less tightly than a power: `2 * 3 ** 2` is `18.0`. `^` is the power operator, not exclusive or; for that, use [xor](/develop/docs/dev-database-reference-sql-functions-numeric-xor). ## NULLs and edge cases | Input | Result | | --- | --- | | `pow(NULL, 2)`, `pow(2, NULL)` | `NULL` | | `pow(2, 10)` | `1024.0` | | `pow(0, 0)` | `1.0` | | `pow(0, -1)` | `inf` | | `pow(-8, 3)` | `-512.0` | | `pow(-8, 1.0 / 3)`, `pow(-1, 0.5)` | `nan` | | `pow(2, 1024)` | `inf` | | `pow(2, -1075)` | `0.0` | | `pow('nan'::DOUBLE, 0)`, `pow(1, 'nan'::DOUBLE)` | `1.0` | | `pow('inf'::DOUBLE, -1)`, `pow(0.5, 'inf'::DOUBLE)` | `0.0` | | `pow(3, 40)` | `1.2157665459056929e+19` (not exact) | | `-2 ** 2` | `4.0` | | `2 ** 3 ** 2` | `64.0` | | `2 * 3 ** 2` | `18.0` | | `pow('12', 2)` | `144.0` | | `pow('abc', 2)` | Error: `Could not convert string 'abc' to DOUBLE` | | `pow(2)` | Error: `No function matches the given name and argument types 'pow(INTEGER_LITERAL)'` | | `pow(true, 2)` (a boolean, date, interval, `BLOB` or list) | Error: `No function matches the given name and argument types 'pow(BOOLEAN, 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-numeric-pow#set-up-the-examples): ``` run("SELECT pow(NULL, 2), pow(2, NULL), pow(2, 10), pow(0, 0), pow(0, -1), pow(-8, 3), pow(-8, 1.0 / 3), pow(-1, 0.5)") run("SELECT pow(2, 1024), pow(2, -1075), pow('nan'::DOUBLE, 0), pow(1, 'nan'::DOUBLE), " "pow('inf'::DOUBLE, -1), pow(0.5, 'inf'::DOUBLE), pow(3, 40)") run("SELECT -2 ** 2, 2 ** 3 ** 2, 2 * 3 ** 2, -2 ^ 2, 2 ^ 3 ^ 2") run("SELECT -(2 ** 2), 2 ** (3 ** 2)") run("SELECT typeof(pow(2, 2)), typeof(pow(2::INTEGER, 2::INTEGER)), typeof(pow(2.5, 2)), typeof(2 ** 10)") run(f"SELECT pow('12', 2) FROM {TABLE} LIMIT 1") run(f"SELECT pow('abc', 2) FROM {TABLE} LIMIT 1") run("SELECT pow(2)") run("SELECT pow(true, 2)") ``` ``` [(None, None, 1024.0, 1.0, inf, -512.0, nan, nan)] [(inf, 0.0, 1.0, 1.0, 0.0, 0.0, 1.2157665459056929e+19)] [(4.0, 64.0, 18.0, 4.0, 64.0)] [(-4.0, 512.0)] [('DOUBLE', 'DOUBLE', 'DOUBLE', 'DOUBLE')] [(144.0,)] OSError: Could not convert string 'abc' to DOUBLE InternalError: Binder Error: No function matches the given name and argument types 'pow(INTEGER_LITERAL)'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'pow(BOOLEAN, INTEGER_LITERAL)'. You might need to add explicit type casts. ``` ## Examples The value of each account after its number of years, with the rate compounded once a year: ``` run(f"SELECT id, round(amount * pow(1 + rate, years), 2) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 1628.89), (2, 2898.19), (3, 583.2), (4, None)] ``` The growth factor four ways: the two function names and the two operators: ``` run(f"SELECT id, pow(1 + rate, years), power(1 + rate, years), (1 + rate) ** years, (1 + rate) ^ years " f"FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 1.628894626777442, 1.628894626777442, 1.628894626777442, 1.628894626777442), (2, 1.1592740743, 1.1592740743, 1.1592740743, 1.1592740743), (3, 0.7290000000000001, 0.7290000000000001, 0.7290000000000001, 0.7290000000000001), (4, None, None, None, None)] ``` Keep only the accounts that end above 2,000: ``` run(f"SELECT id, amount FROM {TABLE} WHERE amount * pow(1 + rate, years) > 2000 ORDER BY id LIMIT 10") ``` ``` [(2, 2500.0)] ``` ## 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 `pow()` and the `**` and `^` operators are always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the columns and the Query Engine computes `pow()` for each row it returns. - **In `WHERE`,** the scan sends the columns for every row, and a `FILTER` step in the Query Engine computes `pow()` 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 amount * pow(1 + rate, years) > 2000") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #3 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ((amount * pow((1.0 + rate│ │ ), CAST(years AS DOUBLE)))│ │ > 2000.0) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ amount │ │ rate │ │ years │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Compare the raw column instead of its power.** `rate ** 2 > 0.0025` runs in a `FILTER` step; the same condition as a range on the column, `rate > 0.05 OR rate < -0.05`, is pushed down to VAST DataBase, so rows that don't match never leave storage. Its plan has no `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE rate ** 2 > 0.0025") plan(f"SELECT id FROM {TABLE} WHERE rate > 0.05 OR rate < -0.05") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ((rate ** 2.0) > 0.0025) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ rate │ │ id │ │ │ └───────────────────────────┘ ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **Store the result if you filter on it often.** Compute it when you write the rows and keep it in its own column, so the condition is a comparison of a column with a constant. - **Combine it with a pushed-down condition.** In `id > 100 AND amount * pow(1 + rate, years) > 2000`, `id > 100` is still evaluated in VAST DataBase, so `pow()` runs only on the rows that pass it. ## Limitations and errors - **Numbers only.** A boolean, date, interval, `BLOB` or list fails with `No function matches the given name and argument types`; the error lists the one form `pow` accepts, `pow(DOUBLE, DOUBLE) -> DOUBLE`. A string is converted when the query runs, and one that isn't a number fails with `Could not convert string 'abc' to DOUBLE`. - **Always a `DOUBLE`.** There's no integer power: `pow(2, 10)` is `1024.0`, and large results are rounded to the nearest `DOUBLE`. To multiply an integer by a power of two exactly, shift instead: `3 << 4` is the integer `48`, where `3 * pow(2, 4)` is `48.0`; see [shift left](/develop/docs/dev-database-reference-sql-functions-operators-shift-left). - **No error for impossible results.** A negative base with a fractional exponent returns `nan`, and an overflow returns `inf`. Test for them with [isnan](/develop/docs/dev-database-reference-sql-functions-numeric-isnan) and [isinf](/develop/docs/dev-database-reference-sql-functions-numeric-isinf). - **No `square` function.** `square(x)` fails with `Scalar Function with name square does not exist!`. Use `x * x` or `pow(x, 2)`. ``` run("SELECT isnan(pow(-8, 1.0 / 3)), isinf(pow(2, 1024))") run("SELECT square(3)") run("SELECT 3 * 3, pow(3, 2)") ``` ``` [(True, True)] InternalError: Catalog Error: Scalar Function with name square does not exist! [(9, 9.0)] ``` ## Similar functions | Function | Computes | Result for 2 and 10 (`pow(2, 10)` gives `1024.0`) | | --- | --- | --- | | `x ** y`, `x ^ y` | the same as `pow` | `1024.0` | | [exp](/develop/docs/dev-database-reference-sql-functions-numeric-exp) `(y * ln(x))` | the same power, through e | `1024.0` | | [sqrt](/develop/docs/dev-database-reference-sql-functions-numeric-sqrt) | `pow(x, 0.5)` for `x` ≥ 0 | `sqrt(1024)` is `32.0` | | [cbrt](/develop/docs/dev-database-reference-sql-functions-numeric-cbrt) | the cube root, also of negative numbers | `cbrt(1024)` is `10.079368399158987` | | [shift left](/develop/docs/dev-database-reference-sql-functions-operators-shift-left) `<<` | `a * pow(2, n)` as an integer | `3 << 4` is `48`; `3 * pow(2, 4)` is `48.0` | ``` run("SELECT pow(2, 10), power(2, 10), 2 ** 10, 2 ^ 10, exp(10 * ln(2)), sqrt(1024), cbrt(1024)") run("SELECT 3 << 4, 3 * pow(2, 4)") ``` ``` [(1024.0, 1024.0, 1024.0, 1024.0, 1024.0, 32.0, 10.079368399158987)] [(48, 48.0)] ``` 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): all the numeric functions. - [sqrt](/develop/docs/dev-database-reference-sql-functions-numeric-sqrt), [cbrt](/develop/docs/dev-database-reference-sql-functions-numeric-cbrt), [exp](/develop/docs/dev-database-reference-sql-functions-numeric-exp) and [ln](/develop/docs/dev-database-reference-sql-functions-numeric-ln). - [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.