---
title: "abs"
slug: "dev-database-reference-sql-functions-numeric-abs"
updated: 2026-10-30T18:18:51Z
published: 2026-10-30T18:18:51Z
canonical: "docs.vastdata.com/dev-database-reference-sql-functions-numeric-abs"
---

> ## 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.

# abs

*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) › Sign and rounding.* Returns the absolute value of a number: the number without its sign, in the same type. The prefix operator `@` is the same function.

## Syntax

```
abs(x)
@ x
```

| Argument | Type | Description |
| --- | --- | --- |
| `x` | any number: `TINYINT`, `SMALLINT`, `INTEGER`, `BIGINT`, `HUGEINT`, the unsigned integer types, `DECIMAL`, `FLOAT` or `DOUBLE` | The value to take the absolute value of. |

**Returns:** the type of `x`.

**Aliases:** the prefix operator `@`.

## 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_abs`. 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 stock changes: a change in price (`DOUBLE`), a change in quantity (`INTEGER`) and an amount (`DECIMAL`). 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_abs"'

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, "<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}.changes"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, delta DOUBLE, qty INTEGER, amount DECIMAL(10, 2))")
run(f"INSERT INTO {TABLE} VALUES "
    "(1, 2.5, 12, 2.45), "
    "(2, -1.25, -18, -1.35), "
    "(3, 0.0, 0, 0.00), "
    "(4, NULL, NULL, NULL)")
```

```
[]
[]
[(4,)]
```

## What it does

`abs(x)` returns `x` for a positive value or zero, and `-x` for a negative value. The result has the type of `x`: `abs(-5)` is the `INTEGER` 5, `abs(-2.45)` is the `DECIMAL(3,2)` 2.45, and the absolute value of a `TINYINT` column is a `TINYINT`. On the unsigned integer types, which have no negative values, it returns the value unchanged.

On `DOUBLE` and `FLOAT` values, `abs` clears the sign of a negative zero (`abs(-0.0::DOUBLE)` is `0.0`, and `signbit()` of it is false), turns `-inf` into `inf`, and leaves `nan` as `nan`.

`@ x` is the same function. `@` applies to the whole expression after it: `@ -5 + 1` is `@ (-5 + 1)`, which is 4. Write `abs(-5) + 1` when you mean the absolute value plus one.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| `x` is NULL | `NULL` |
| `abs(-0.0::DOUBLE)` | `0.0`, without the sign |
| `abs(&apos;-inf&apos;::DOUBLE)` | `inf` |
| `abs(&apos;nan&apos;::DOUBLE)` | `nan` |
| `abs(-2.45)` | `2.45`, a `DECIMAL(3,2)` |
| `abs(-5)` | `5`, an `INTEGER` |
| `@ -5 + 1` | `4`: `@` applies to `-5 + 1` |
| The smallest value of a signed integer type: `abs((-128)::TINYINT)` | Error: `Overflow on abs(-128)` |
| `abs(-3::UTINYINT)` | `253`: the cast comes first, and `-(3::UTINYINT)` wraps around to 253 |
| A string, even `&apos;12&apos;` | Error: `Could not choose a best candidate function for the function call &quot;abs(STRING_LITERAL)&quot;` |
| A date, boolean, `BLOB`, list or interval | Error: `No function matches the given name and argument types` |

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-abs#set-up-the-examples):

```
run("SELECT abs(NULL), abs(-0.0::DOUBLE), signbit(abs(-0.0::DOUBLE)), abs('-inf'::DOUBLE), abs('nan'::DOUBLE)")
run("SELECT abs(-2.45), typeof(abs(-2.45)), abs(-5), typeof(abs(-5)), @ -5, @ -5 + 1")
run("SELECT abs((-128)::TINYINT)")
run("SELECT abs(-3::UTINYINT)")
run("SELECT abs('12')")
run("SELECT abs(DATE '2026-10-16')")
```

```
[(None, 0.0, False, inf, nan)]
[(Decimal('2.45'), 'DECIMAL(3,2)', 5, 'INTEGER', 5, 4)]
OSError: Overflow on abs(-128)
[(253,)]
InternalError: Binder Error: Could not choose a best candidate function for the function call "abs(STRING_LITERAL)". In order to select one, please add explicit type casts.
InternalError: Binder Error: No function matches the given name and argument types 'abs(DATE)'. You might need to add explicit type casts.
```

## Examples

The size of each change, for each column type. Each result keeps the type of its column:

```
run(f"SELECT id, abs(delta), @ delta, abs(qty), abs(amount) FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 2.5, 2.5, 12, Decimal('2.45')), (2, 1.25, 1.25, 18, Decimal('1.35')), (3, 0.0, 0.0, 0, Decimal('0.00')), (4, None, None, None, None)]
```

Keep the changes of more than 1 in either direction:

```
run(f"SELECT id, delta FROM {TABLE} WHERE abs(delta) > 1 ORDER BY id LIMIT 10")
```

```
[(1, 2.5), (2, -1.25)]
```

## 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 `abs()` and `@` are always computed by the Query Engine:

- **In the `SELECT` list,** the scan reads the column and the Query Engine computes `abs()` for each row it returns.
- **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes `abs()` 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 abs(delta) > 1")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│     (abs(delta) > 1.0)    │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│           delta           │
│             id            │
│                           │
└───────────────────────────┘
```

## Make it faster

- **Write the condition on the raw column.** `abs(delta) &gt; 1` is the same as `delta &gt; 1 OR delta &lt; -1`, and that form 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 delta > 1 OR delta < -1")
```

```
┌───────────────────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│      Projections: id      │
│                           │
└───────────────────────────┘
```

- **Use `BETWEEN` for "close to zero".** `abs(qty) &lt;= 1` runs in a `FILTER` step; `qty BETWEEN -1 AND 1` is pushed down.
- **Combine it with a pushed-down condition.** In `id &gt; 1 AND abs(delta) &gt; 1`, the `FILTER` step holds only `abs(delta) &gt; 1`: `id &gt; 1` is evaluated in VAST DataBase, so `abs()` runs only on the rows that pass it.

## Limitations and errors

- **The smallest value of a signed integer type overflows.** Its absolute value doesn't fit the type: `abs((-128)::TINYINT)` fails with `Overflow on abs(-128)`, and the same happens for the smallest `SMALLINT`, `INTEGER`, `BIGINT` and `HUGEINT`. One such row stops the whole query. Cast the value to a wider type first.
- **A cast binds more tightly than the minus sign.** In `-3::UTINYINT` the cast comes first, and in `-9223372036854775808::BIGINT` the number 9223372036854775808 is cast to `BIGINT` before the minus, which fails with `Type INT128 with value 9223372036854775808 can&apos;t be cast because the value is out of range for the destination type INT64`. Put the negative number in parentheses: `(-128)::TINYINT`.
- **Strings aren't converted.** `abs(&apos;12&apos;)` fails with `Could not choose a best candidate function`. Cast the string to a number first.
- **Numbers only.** A date, a boolean, a `BLOB`, a list or an interval fails with `No function matches the given name and argument types`.

```
run("SELECT abs((-128)::TINYINT)")
run("SELECT abs(CAST((-128)::TINYINT AS SMALLINT)), abs(CAST('12' AS INTEGER))")
```

```
OSError: Overflow on abs(-128)
[(128, 12)]
```

## Similar functions

| Function | Returns | Result for `-5` | Result for `-0.0::DOUBLE` |
| --- | --- | --- | --- |
| `abs(x)`, `@ x` | the value without its sign, in the type of `x` | `5` | `0.0` |
| [sign](/develop/docs/dev-database-reference-sql-functions-numeric-sign) | `-1`, `0` or `1`, as a `TINYINT` | `-1` | `0` |
| [signbit](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-signbit) | whether the sign bit is set, as a `BOOLEAN` | `true` | `true` |

```
run("SELECT abs(-5), @ -5, sign(-5), signbit(-5), abs(-0.0::DOUBLE), sign(-0.0::DOUBLE), signbit(-0.0::DOUBLE)")
run("SELECT abs(-5) + 1, @ -5 + 1")
```

```
[(5, 5, -1, True, 0.0, 0, True)]
[(6, 4)]
```

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.
- [sign](/develop/docs/dev-database-reference-sql-functions-numeric-sign) and [signbit](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-signbit).
- [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.