---
title: "// (integer division)"
slug: "dev-database-reference-sql-functions-operators-integer-division"
updated: 2026-10-30T18:18:56Z
published: 2026-10-30T18:18:56Z
canonical: "docs.vastdata.com/dev-database-reference-sql-functions-operators-integer-division"
---

> ## 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.

# // (integer division)

*Applies to VAST Cluster 5.5.*

*[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Operators and predicates](/develop/docs/dev-database-reference-sql-functions-operators-and-predicates) › Arithmetic operators.* `a // b` divides two integers and drops the fraction toward zero: `7 // 2` is 3, and `-7 // 2` is -3. The result keeps the integer type, and dividing by zero returns NULL. On `DECIMAL`, `FLOAT` and `DOUBLE` values, `//` doesn't drop the fraction: `7.5 // 2` is 3.75.

## Syntax

```
a // b
```

| Argument | Type | Description |
| --- | --- | --- |
| `a` | any integer type, `DECIMAL`, `FLOAT` or `DOUBLE` | The dividend. |
| `b` | any integer type, `DECIMAL`, `FLOAT` or `DOUBLE` | The divisor. |

**Returns:** for two integers of the same type, that type: `INTEGER // INTEGER` is an `INTEGER`. `FLOAT // FLOAT` is a `FLOAT`; `DOUBLE` and `DECIMAL` arguments give a `DOUBLE`.

## 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_operators_integer_division`. 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 log events: an offset in seconds (`INTEGER`, negative for an event before the reference time), a size in bytes (`BIGINT`), a ratio (`DOUBLE`) and an amount (`DECIMAL(10,2)`). 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_operators_integer_division"'

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}.events"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, seconds INTEGER, bytes BIGINT, ratio DOUBLE, amount DECIMAL(10,2))")
run(f"INSERT INTO {TABLE} VALUES "
    "(1, 3725, 1536, 7.5, 7.50), "
    "(2, -90, 5000000, -7.5, -7.50), "
    "(3, 0, 0, 0.0, 0.00), "
    "(4, NULL, NULL, NULL, NULL)")
```

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

## What it does

On integers, `a // b` divides and drops the fraction **toward zero**: the result is the integer part of the exact quotient, whatever its sign.

| Call | Exact quotient | Result |
| --- | --- | --- |
| `7 // 2` | 3.5 | `3` |
| `-7 // 2` | -3.5 | `-3` |
| `7 // -2` | -3.5 | `-3` |
| `-7 // -2` | 3.5 | `3` |

For a negative quotient, this isn't rounding down: -3.5 becomes -3, not -4. To round down, use [fdiv](/develop/docs/dev-database-reference-sql-functions-numeric-fdiv): `fdiv(-7, 2)` is -4.0. The remainder that goes with `//` is [% (modulo)](/develop/docs/dev-database-reference-sql-functions-operators-modulo), so `a = (a // b) * b + a % b`.

**Dividing by zero returns NULL** for every argument type, also `DOUBLE`: `1 // 0` and `1.0::DOUBLE // 0` are both NULL. (The `/` operator returns `inf` instead.)

**Not integer division for other types.** With a `DECIMAL`, `FLOAT` or `DOUBLE` argument, `//` divides without dropping the fraction: `7.5 // 2` is 3.75, the same as `7.5 / 2`, and `-0.5::DOUBLE // 1` is -0.5. A `DECIMAL` argument gives a `DOUBLE`. To get a whole number, use [fdiv](/develop/docs/dev-database-reference-sql-functions-numeric-fdiv) (rounded down) or [trunc](/develop/docs/dev-database-reference-sql-functions-numeric-trunc) of the quotient (toward zero).

**A numeric string is converted.** In `&apos;7200&apos; // seconds`, the string is converted to the type of the other side. A string that isn't a number fails with `Could not convert string &apos;abc&apos; to INT32`.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| `NULL // 1`, `1 // NULL` | `NULL` |
| `7 // 2`, `-7 // 2`, `7 // -2`, `-7 // -2` | `3`, `-3`, `-3`, `3` |
| `1 // 0`, `1.0::DOUBLE // 0` | `NULL`, `NULL` |
| `7.5 // 2`, `typeof(7.5 // 2)` | `3.75`, `DOUBLE` |
| `-0.5::DOUBLE // 1` | `-0.5` |
| `2.45 // 0.7` | `3.5000000000000004` |
| `&apos;inf&apos;::DOUBLE // 1`, `1 // &apos;inf&apos;::DOUBLE`, `&apos;nan&apos;::DOUBLE // 1` | `inf`, `0.0`, `nan` |
| The smallest value of a signed integer type `// -1` | Error: `Overflow in division of -128 / -1` (for a `TINYINT`) |
| `&apos;abc&apos; // seconds` | Error: `Could not convert string &apos;abc&apos; to INT32` |
| A boolean, date, `INTERVAL`, `BLOB` or list | 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-operators-integer-division#set-up-the-examples):

```
run("SELECT NULL // 1, 1 // NULL, 7 // 2, -7 // 2, 7 // -2, -7 // -2")
run("SELECT 1 // 0, 1.0::DOUBLE // 0, 7.5 // 2, typeof(7.5 // 2), -0.5::DOUBLE // 1, 2.45 // 0.7")
run("SELECT 'inf'::DOUBLE // 1, 1 // 'inf'::DOUBLE, 'nan'::DOUBLE // 1")
run("SELECT (-128)::TINYINT // (-1)::TINYINT")
run(f"SELECT '7200' // seconds, 'abc' // seconds FROM {TABLE} WHERE id = 1")
run("SELECT INTERVAL 1 DAY // 2")
```

```
[(None, None, 3, -3, -3, 3)]
[(None, None, 3.75, 'DOUBLE', -0.5, 3.5000000000000004)]
[(inf, 0.0, nan)]
OSError: Overflow in division of -128 / -1
OSError: Could not convert string 'abc' to INT32
InternalError: Binder Error: No function matches the given name and argument types '//(INTERVAL, INTEGER_LITERAL)'. You might need to add explicit type casts.
```

## Examples

An offset in whole minutes and the seconds left over, and a size in whole KiB. Event 2 is 90 seconds before the reference time, and both `//` and `%` keep the sign of its negative offset:

```
run(f"SELECT id, seconds // 60, seconds % 60, bytes // 1024 FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 62, 5, 1), (2, -1, -30, 4882), (3, 0, 0, 0), (4, None, None, None)]
```

The types of the results:

```
run(f"SELECT typeof(seconds // 60), typeof(bytes // 1024), typeof(ratio // 2), typeof(amount // 2) FROM {TABLE} WHERE id = 1")
```

```
[('INTEGER', 'BIGINT', 'DOUBLE', 'DOUBLE')]
```

On a `DOUBLE` and a `DECIMAL`, `//` keeps the fraction; `fdiv` rounds down and `trunc` of the quotient drops the fraction toward zero:

```
run(f"SELECT id, ratio // 2, amount // 2, fdiv(ratio, 2), trunc(ratio / 2) FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 3.75, 3.75, 3.0, 3.0), (2, -3.75, -3.75, -4.0, -3.0), (3, 0.0, 0.0, 0.0, 0.0), (4, None, None, None, None)]
```

Keep only the events in the 62nd minute:

```
run(f"SELECT id, seconds FROM {TABLE} WHERE seconds // 60 = 62 ORDER BY id LIMIT 10")
```

```
[(1, 3725)]
```

## 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 quotient of a column, so `seconds // 60` is computed by the Query Engine:

- **In the `SELECT` list,** the scan reads the column and the Query Engine computes the quotient for each row it returns.
- **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes the quotient 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 seconds // 60 = 62")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│   ((seconds // 60) = 62)  │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│          seconds          │
│             id            │
│                           │
└───────────────────────────┘
```

## Make it faster

- **Write the range instead.** For non-negative values, `seconds // 60 = 62` is the same as `seconds &gt;= 3720 AND seconds &lt; 3780`, a range on the raw column that's pushed down to VAST DataBase. The plan has no `FILTER` step. For negative values the range is different, because `//` drops toward zero: `seconds // 60 = 0` holds from -59 to 59.

```
plan(f"SELECT id FROM {TABLE} WHERE seconds >= 3720 AND seconds < 3780")
run(f"SELECT id, seconds FROM {TABLE} WHERE seconds >= 3720 AND seconds < 3780 ORDER BY id LIMIT 10")
```

```
┌───────────────────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│      Projections: id      │
│                           │
└───────────────────────────┘
[(1, 3725)]
```

- **Store a bucket you filter on often.** If you often filter on the minute or another bucket, compute it when you write the rows and keep it in its own column.
- **Combine it with a pushed-down condition.** In `id &gt; 100 AND seconds // 60 = 62`, `id &gt; 100` is still evaluated in VAST DataBase, so the division runs only on the rows that pass it.

## Limitations and errors

- **The smallest value of a signed integer type divided by -1 stops the query.** Its positive counterpart doesn't fit the type, so `(-128)::TINYINT // -1` fails with `Overflow in division of -128 / -1`. Cast to a wider type first.
- **No `DIV` operator and no `div()` or `intdiv()` function.** `7 DIV 2` is a syntax error, and the functions fail with `Scalar Function with name &#x2026; does not exist!`. Use `//` or [divide](/develop/docs/dev-database-reference-sql-functions-numeric-divide).
- **No `INTERVAL` division.** `INTERVAL 1 DAY // 2` fails with `No function matches the given name and argument types`.
- **Booleans, dates, `BLOB` values and lists** fail the same way.

```
run("SELECT CAST((-128)::TINYINT AS INTEGER) // -1")
run("SELECT div(7, 2)")
run("SELECT 7 DIV 2")
```

```
[(128,)]
InternalError: Catalog Error: Scalar Function with name div does not exist!
InternalError: Parse query: 'SELECT 7 DIV 2' failed with: Parser Error: syntax error at or near "2"
```

## Similar functions

| Function | Does | `-7` by `2` | `7.5` by `2` | `1` by `0` |
| --- | --- | --- | --- | --- |
| `a // b` | drops the fraction toward zero, on integers | `-3` | `3.75` | `NULL` |
| [divide](/develop/docs/dev-database-reference-sql-functions-numeric-divide) | the same as `//` | `-3` | `3.75` | `NULL` |
| [fdiv](/develop/docs/dev-database-reference-sql-functions-numeric-fdiv) | rounds down, always | `-4.0` | `3.0` | `inf` |
| [/ (division)](/develop/docs/dev-database-reference-sql-functions-operators-division) | keeps the fraction, as a `DOUBLE` | `-3.5` | `3.75` | `inf` |
| [% (modulo)](/develop/docs/dev-database-reference-sql-functions-operators-modulo) | the remainder that goes with `//` | `-1` | `1.5` | `NULL` |

```
run("SELECT -7 // 2, divide(-7, 2), fdiv(-7, 2), -7 / 2, -7 % 2")
run("SELECT 7.5 // 2, divide(7.5, 2), fdiv(7.5, 2), 7.5 / 2, 7.5 % 2")
run("SELECT 1 // 0, divide(1, 0), fdiv(1, 0), 1 / 0, 1 % 0")
```

```
[(-3, -3, -4.0, -3.5, -1)]
[(3.75, 3.75, 3.0, 3.75, Decimal('1.5'))]
[(None, None, inf, inf, None)]
```

Clean up:

```
run(f"DROP TABLE IF EXISTS {TABLE}")
run(f"DROP SCHEMA IF EXISTS {SCHEMA}")
conn.close()
```

```
[]
[]
```

## See also

- [Operators and predicates](/develop/docs/dev-database-reference-sql-functions-operators-and-predicates#arithmetic): all the arithmetic operators.
- [/ (division)](/develop/docs/dev-database-reference-sql-functions-operators-division), [% (modulo)](/develop/docs/dev-database-reference-sql-functions-operators-modulo), [divide](/develop/docs/dev-database-reference-sql-functions-numeric-divide) and [fdiv](/develop/docs/dev-database-reference-sql-functions-numeric-fdiv).
- [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.