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

> ## 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.

# << (shift left)

*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) › Bitwise operators.* `a &lt;&lt; n` shifts the bits of `a` left by `n` places, which multiplies `a` by 2 to the power `n`: `1 &lt;&lt; 4` is `16`. A result that doesn't fit the type, a negative `a` and a negative `n` are errors.

## Syntax

```
a << n
```

| Argument | Type | Description |
| --- | --- | --- |
| `a` | An integer type (`TINYINT` to `HUGEINT`, signed or unsigned), or `BIT` | The value to shift. It must not be negative. |
| `n` | An integer | How many places to shift. It must not be negative. |

**Returns:** the integer type of the arguments: `1 &lt;&lt; 4` is an `INTEGER`. For a `BIT` value, a `BIT`.

## 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_shift_left`. 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 values `n`, each with a number of places `k` to shift it by. 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_shift_left"'

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}.shifts"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, n INTEGER, k INTEGER)")
run(f"INSERT INTO {TABLE} VALUES (1, 1, 4), (2, 3, 2), (3, 5, 0), (4, NULL, NULL)")
```

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

## What it does

`a &lt;&lt; n` moves every bit of `a` up by `n` places and fills the places it leaves with zeros, so the result is `a` times 2 to the power `n`: `3 &lt;&lt; 4` is `48`, the same as `3 * 16`.

The result has the type of the arguments, and it must fit that type. The shift doesn't wrap around or drop bits:

- **A result too large for the type fails** with `Overflow in left shift`. For a signed type, the result can't reach the sign bit: `1 &lt;&lt; 30` is fine in an `INTEGER`, but `1 &lt;&lt; 31` fails. An unsigned type can use its top bit: `1::UTINYINT &lt;&lt; 7` is `128`.
- **A shift by the whole width or more fails.** For a signed type the error is `Left-shift value 64 is out of range` (for a `BIGINT`); for an unsigned type it's `Overflow in left shift`. `0 &lt;&lt; 100` is `0`.
- **A negative `a` or a negative `n` fails**, with `Cannot left-shift negative number -1` or `Cannot left-shift by negative number -1`.

To shift further, cast `a` to a wider type first: `1::BIGINT &lt;&lt; 62` works.

`+` binds more tightly than `&lt;&lt;`: `1 &lt;&lt; 2 + 1` is `1 &lt;&lt; 3`, which is `8`.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| `1 &lt;&lt; 4`, `1 &lt;&lt; 30`, `1 &lt;&lt; 0`, `0 &lt;&lt; 100` | `16`, `1073741824`, `1`, `0` |
| `1 &lt;&lt; 2 + 1` | `8` |
| `NULL &lt;&lt; 1`, `1 &lt;&lt; NULL` | `NULL` |
| `1 &lt;&lt; 31` | Error: `Overflow in left shift (1 &lt;&lt; 31)` |
| `1::BIGINT &lt;&lt; 62` | `4611686018427387904` |
| `1::BIGINT &lt;&lt; 63` | Error: `Overflow in left shift (1 &lt;&lt; 63)` |
| `1::BIGINT &lt;&lt; 64` | Error: `Left-shift value 64 is out of range` |
| `1::UTINYINT &lt;&lt; 7`, `1::UBIGINT &lt;&lt; 63` | `128`, `9223372036854775808` |
| `1::UTINYINT &lt;&lt; 8` | Error: `Overflow in left shift (1 &lt;&lt; 8)` |
| `3::TINYINT &lt;&lt; 6` | Error: `Overflow in left shift (3 &lt;&lt; 6)` |
| `1::HUGEINT &lt;&lt; 126` | `85070591730234615865843651857942052864` |
| `-1 &lt;&lt; 1` | Error: `Cannot left-shift negative number -1` |
| `1 &lt;&lt; -1` | Error: `Cannot left-shift by negative number -1` |
| `1.5 &lt;&lt; 1` (a `DECIMAL`) | Error: `No function matches the given name and argument types &apos;&lt;&lt;(DECIMAL(2,1), INTEGER_LITERAL)&apos;` |
| `&apos;12&apos; &lt;&lt; k` (a string) | Error: `Could not choose a best candidate function for the function call &quot;&lt;&lt;(STRING_LITERAL, INTEGER)&quot;` |

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-shift-left#set-up-the-examples):

```
run("SELECT 1 << 4, 1 << 30, 1 << 0, 0 << 100, 1 << 2 + 1, NULL << 1, 1 << NULL")
run("SELECT 1 << 31")
run("SELECT 1::BIGINT << 62")
run("SELECT 1::BIGINT << 63")
run("SELECT 1::BIGINT << 64")
run("SELECT 1::UTINYINT << 7, 1::UBIGINT << 63")
run("SELECT 1::UTINYINT << 8")
run("SELECT 3::TINYINT << 6")
run("SELECT 1::HUGEINT << 126")
run("SELECT -1 << 1")
run("SELECT 1 << -1")
run("SELECT 1.5 << 1")
run(f"SELECT '12' << k FROM {TABLE} LIMIT 1")
```

```
[(16, 1073741824, 1, 0, 8, None, None)]
OSError: Overflow in left shift (1 << 31)
[(4611686018427387904,)]
OSError: Overflow in left shift (1 << 63)
OSError: Left-shift value 64 is out of range
[(128, 9223372036854775808)]
OSError: Overflow in left shift (1 << 8)
OSError: Overflow in left shift (3 << 6)
[(Decimal('85070591730234615865843651857942052864'),)]
OSError: Cannot left-shift negative number -1
OSError: Cannot left-shift by negative number -1
InternalError: Binder Error: No function matches the given name and argument types '<<(DECIMAL(2,1), INTEGER_LITERAL)'. You might need to add explicit type casts.
InternalError: Binder Error: Could not choose a best candidate function for the function call "<<(STRING_LITERAL, INTEGER)". In order to select one, please add explicit type casts.
```

## Examples

Shift each value by its own number of places:

```
run(f"SELECT id, n, k, n << k FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 1, 4, 16), (2, 3, 2, 12), (3, 5, 0, 5), (4, None, None, None)]
```

Build a bit mask with one bit set, and keep the rows whose shifted value is larger than 10:

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

```
[(1, 16), (2, 4), (3, 1), (4, None)]
[(1,), (2,)]
```

## 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 an operation on a column, so `&lt;&lt;` on a column is always computed by the Query Engine:

- **In the `SELECT` list,** the scan reads the columns and the Query Engine computes `&lt;&lt;` for each row it returns.
- **In `WHERE`,** the scan sends the columns for every row, and a `FILTER` step in the Query Engine computes `&lt;&lt;` and keeps the rows that match. No rows are skipped in storage.

An error on one row cancels the whole query, in `SELECT` and in `WHERE`: one negative value in the column is enough. The plan of the `WHERE` example shows the `FILTER` step above the scan:

```
plan(f"SELECT id FROM {TABLE} WHERE (n << k) > 10")
run("SELECT n << k FROM (VALUES (1, 1), (-18, 2)) v(n, k)")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #2            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│      ((n << k) > 10)      │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│             n             │
│             k             │
│             id            │
│                           │
└───────────────────────────┘
OSError: Cannot left-shift negative number -18
```

## Make it faster

- **Shift the constant, not the column.** A shift of constants is computed before the scan, so `n = 1 &lt;&lt; 10` is a comparison of the raw column with a constant, which is pushed down to VAST DataBase. The plan has no `FILTER` step:

```
plan(f"SELECT id FROM {TABLE} WHERE n = 1 << 10")
```

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

## Limitations and errors

- **Overflow is an error.** A result that doesn't fit the type fails with `Overflow in left shift`, and the whole query stops. Cast `a` to a wider type, such as `BIGINT` or `HUGEINT`, before you shift.
- **No negative values.** A negative `a` fails with `Cannot left-shift negative number`, and a negative `n` with `Cannot left-shift by negative number`. To multiply a negative number by a power of 2, use `*`: `-3 * 16`.
- **Integers and `BIT` only.** A `DECIMAL`, `DOUBLE`, `FLOAT`, `BOOLEAN`, `DATE`, `INTERVAL`, `BLOB` or list fails with `No function matches the given name and argument types`. A string literal fails with `Could not choose a best candidate function`, because it could be a `BIT` or an integer; cast it.
- **No `shiftleft` function.** `shiftleft(1, 4)` fails with `Scalar Function with name shiftleft does not exist!`. Use `&lt;&lt;`.

```
run("SELECT -3 * 16, CAST('12' AS INTEGER) << 1")
run("SELECT shiftleft(1, 4)")
```

```
[(-48, 24)]
InternalError: Catalog Error: Scalar Function with name shiftleft does not exist!
```

## Similar functions

| Operator or function | What it does | Result for `3` and `4` |
| --- | --- | --- |
| `a &lt;&lt; n` | shifts left by `n` bits; an error on overflow or a negative `a` | `48` |
| `a * 2^n` with [*](/develop/docs/dev-database-reference-sql-functions-operators-multiplication) | multiplies; works for negative `a` | `48` |
| [pow](/develop/docs/dev-database-reference-sql-functions-numeric-pow) `(2, n)` | 2 to the power `n`, as a `DOUBLE` | `3 * pow(2, 4)` is `48.0` |
| [>>](/develop/docs/dev-database-reference-sql-functions-operators-shift-right) | shifts right by `n` bits | `3 &gt;&gt; 4` is `0` |

```
run("SELECT 3 << 4, 3 * 16, 3 * pow(2, 4), 3 >> 4")
```

```
[(48, 48, 48.0, 0)]
```

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): all the operators.
- [>> (shift right)](/develop/docs/dev-database-reference-sql-functions-operators-shift-right), [& (bitwise AND)](/develop/docs/dev-database-reference-sql-functions-operators-bitwise-and).
- [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.