---
title: "md5_number"
slug: "dev-database-reference-sql-functions-binary-hash-uuid-md5-number"
updated: 2026-10-30T18:18:51Z
published: 2026-10-30T18:18:51Z
canonical: "docs.vastdata.com/dev-database-reference-sql-functions-binary-hash-uuid-md5-number"
---

> ## 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.

# md5_number

*Applies to VAST Cluster 5.5.*

*[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Binary, hash and UUID functions](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid) › Hashes.* Returns the MD5 digest of a string or of a `BLOB` as a number: a signed 128-bit `HUGEINT`. It's the same digest as [md5](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5) gives as text, read as an integer.

## Syntax

```
md5_number(x)
```

| Argument | Type | Description |
| --- | --- | --- |
| `x` | `VARCHAR` or `BLOB` | The value to hash. |

**Returns:** `HUGEINT`, a signed 128-bit integer. The ADBC driver returns it as a `DECIMAL(38, 0)` value, which Python prints as `Decimal`.

## 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_binary_hash_uuid_md5_number`. 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 documents, each with a name and its first bytes. 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_binary_hash_uuid_md5_number"'

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}.documents"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, name VARCHAR, data BLOB)")
run(f"INSERT INTO {TABLE} VALUES "
    "(1, 'hello', '\\x25\\x50\\x44\\x46'::BLOB), "
    "(2, '', ''::BLOB), "
    "(3, 'a', '\\x61'::BLOB), "
    "(4, NULL, NULL)")
```

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

## What it does

`md5_number` computes the same 16-byte MD5 digest as [md5](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5), and reads the bytes as one signed 128-bit integer, **least significant byte first** (little-endian). The bytes come out in the reverse order of the text form:

| Call | Result |
| --- | --- |
| `md5(&apos;abc&apos;)` | `&apos;900150983cd24fb0d6963f7d28e17f72&apos;` |
| `hex(md5_number(&apos;abc&apos;))` | `&apos;727FE1287D3F96D6B04FD23C98500190&apos;`: the same 16 bytes, last first |

So `lower(hex(md5_number(x)))` is not `md5(x)`. The number is signed, so it can be negative: `md5_number(&apos;hello&apos;)` is `-145191729247072235933599665601768308387`, and `md5_number(&apos;abc&apos;)` is positive.

As with `md5`, a `VARCHAR` is hashed as its UTF-8 bytes, so `md5_number(&apos;hello&apos;)` and `md5_number(&apos;hello&apos;::BLOB)` are equal.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| `NULL` | `NULL` |
| `&apos;&apos;` (empty string) | `167830467844043968176572005485231480276`, the digest of no bytes as a number |
| `md5_number(&apos;hello&apos;) = md5_number(&apos;hello&apos;::BLOB)` | `true` |
| `md5_number(&apos;hello&apos;) &lt; 0` | `true`: the result can be negative |
| `lower(hex(md5_number(&apos;hello&apos;))) = md5(&apos;hello&apos;)` | `false`: the byte order differs |
| A number, date, boolean, `UUID`, `BIT` or `HUGEINT` | Error: `No function matches the given name and argument types` |

The same cases, as the cluster returns them. They use the helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number#set-up-the-examples):

```
run("SELECT md5_number(NULL), md5_number(''), md5_number('hello') = md5_number('hello'::BLOB)")
run("SELECT md5_number('hello') < 0, lower(hex(md5_number('hello'))) = md5('hello')")
run("SELECT md5('abc'), hex(md5_number('abc'))")
run("SELECT md5_number(123)")
```

```
[(None, Decimal('167830467844043968176572005485231480276'), True)]
[(True, False)]
[('900150983cd24fb0d6963f7d28e17f72', '727FE1287D3F96D6B04FD23C98500190')]
InternalError: Binder Error: No function matches the given name and argument types 'md5_number(INTEGER_LITERAL)'. You might need to add explicit type casts.
```

## Examples

The digest of each document's name and of its bytes, as numbers:

```
run(f"SELECT id, md5_number(name), md5_number(data) FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, Decimal('-145191729247072235933599665601768308387'), Decimal('64091887192647840467345693085243909311')), (2, Decimal('167830467844043968176572005485231480276'), Decimal('167830467844043968176572005485231480276')), (3, Decimal('129134844867590561315626153795017621772'), Decimal('129134844867590561315626153795017621772')), (4, None, None)]
```

Keep the documents whose name has a negative digest. Of the three names, only `&apos;hello&apos;` has one:

```
run(f"SELECT id, name FROM {TABLE} WHERE md5_number(name) < 0 ORDER BY id LIMIT 10")
```

```
[(1, 'hello')]
```

## 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 `md5_number()` of a column is always computed by the Query Engine:

- **In the `SELECT` list,** the scan reads the column and the Query Engine computes the digest for each row it returns.
- **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine hashes each value 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 md5_number(name) < 0")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│   (md5_number(name) < 0)  │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│            name           │
│             id            │
│                           │
└───────────────────────────┘
```

## Make it faster

- **Store a digest if you filter or look rows up by it.** Compute it when you write the rows and keep it in its own column: the text of [md5](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5) in a `VARCHAR` column, or 64 bits of it from [md5_number_upper](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-upper) or [md5_number_lower](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-lower) in a `UBIGINT` column. A comparison of that column with a constant is evaluated in VAST DataBase.

## Limitations and errors

- **Strings and bytes only.** Other types fail with `No function matches the given name and argument types`, and the error lists `md5_number(VARCHAR) -&gt; HUGEINT` and `md5_number(BLOB) -&gt; HUGEINT`. Cast a number or a `UUID` to `VARCHAR` first.
- **Not the hex digits of `md5`.** The bytes are in reverse order and the number is signed: see [What it does](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number#what-it-does). To compare with an `md5()` value, compare `md5()` results.
- **The halves don't add up to it.** `md5_number_upper(x) * 2^64 + md5_number_lower(x)` is not `md5_number(x)`: see [md5_number_upper](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-upper) for which bytes each half holds.
- **Python reads it as `Decimal`.** The ADBC driver returns a `HUGEINT` as `DECIMAL(38, 0)`; convert it with `int()` in Python if you need an integer.

```
run("SELECT md5_number(DATE '2026-10-16')")
run("SELECT md5_number_upper('abc')::HUGEINT * 18446744073709551616 + md5_number_lower('abc')::HUGEINT = md5_number('abc')")
```

```
InternalError: Binder Error: No function matches the given name and argument types 'md5_number(DATE)'. You might need to add explicit type casts.
[(False,)]
```

## Similar functions

| Function | Result for `&apos;abc&apos;` | Type |
| --- | --- | --- |
| [md5](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5) | `&apos;900150983cd24fb0d6963f7d28e17f72&apos;` | `VARCHAR` |
| `md5_number` | `152195979970564155685860391459828531600` | `HUGEINT` |
| [md5_number_upper](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-upper) | `12704604231530709392`: the digest's first 8 bytes, little-endian | `UBIGINT` |
| [md5_number_lower](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-lower) | `8250560606382298838`: the digest's last 8 bytes, little-endian | `UBIGINT` |
| [hash](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-hash) | a 64-bit hash, not a standard digest | `UBIGINT` |

```
run("SELECT md5('abc'), md5_number('abc'), md5_number_upper('abc'), md5_number_lower('abc')")
run("SELECT typeof(md5_number('a')), typeof(md5_number_upper('a')), typeof(hash('a'))")
```

```
[('900150983cd24fb0d6963f7d28e17f72', Decimal('152195979970564155685860391459828531600'), 12704604231530709392, 8250560606382298838)]
[('HUGEINT', 'UBIGINT', 'UBIGINT')]
```

Clean up:

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

```
[]
[]
```

## See also

- [Binary, hash and UUID functions](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid): all the functions in this family.
- [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.