---
title: "md5_number_upper"
slug: "dev-database-reference-sql-functions-binary-hash-uuid-md5-number-upper"
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-upper"
---

> ## 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_upper

*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 first 8 bytes of the MD5 digest of a string or of a `BLOB`, as an unsigned 64-bit `UBIGINT`. [md5_number_lower](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-lower) returns the other 8 bytes.

## Syntax

```
md5_number_upper(x)
```

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

**Returns:** `UBIGINT`, an unsigned 64-bit integer (0 or more).

## 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_upper`. 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_upper"'

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_upper` computes the 16-byte MD5 digest, as [md5](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5) does, takes its **first 8 bytes**, and reads them as an unsigned 64-bit integer, least significant byte first (little-endian):

| Call | Result |
| --- | --- |
| `md5(&apos;abc&apos;)` | `&apos;900150983cd24fb0d6963f7d28e17f72&apos;`: the first 8 bytes are `90 01 50 98 3c d2 4f b0` |
| `hex(md5_number_upper(&apos;abc&apos;))` | `&apos;B04FD23C98500190&apos;`: the same 8 bytes, last first |
| `md5_number_upper(&apos;abc&apos;)` | `12704604231530709392` |

The result is never negative. It's a 64-bit value that fits a `UBIGINT` column, so it's a compact key or checksum taken from the digest. A `VARCHAR` is hashed as its UTF-8 bytes, so `md5_number_upper(&apos;hello&apos;)` and `md5_number_upper(&apos;hello&apos;::BLOB)` are equal.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| `NULL` | `NULL` |
| `&apos;&apos;` (empty string) | `338333539836370388` |
| `md5_number_upper(&apos;hello&apos;) = md5_number_upper(&apos;hello&apos;::BLOB)` | `true` |
| `md5_number_upper(&apos;a&apos;) &lt; 0` | `false`: the result is unsigned |
| A number, date, boolean, `UUID`, `BIT` or `HUGEINT` | Error: `No function matches the given name and argument types &apos;md5_number(...)&apos;`: the error names `md5_number` |

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

```
run("SELECT md5_number_upper(NULL), md5_number_upper(''), md5_number_upper('hello') = md5_number_upper('hello'::BLOB)")
run("SELECT md5_number_upper('a') < 0, typeof(md5_number_upper('a'))")
run("SELECT md5('abc'), hex(md5_number_upper('abc')), md5('hello'), hex(md5_number_upper('hello'))")
run("SELECT md5_number_upper(123)")
```

```
[(None, 338333539836370388, True)]
[(False, 'UBIGINT')]
[('900150983cd24fb0d6963f7d28e17f72', 'B04FD23C98500190', '5d41402abc4b2a76b9719d911017c592', '762A4BBC2A40415D')]
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 first 8 bytes of the digest of each document's name and of its bytes:

```
run(f"SELECT id, md5_number_upper(name), md5_number_upper(data) FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 8514701317032132957, 1606433174654657727), (2, 338333539836370388, 338333539836370388), (3, 12157170054180749580, 12157170054180749580), (4, None, None)]
```

Spread the documents over 4 buckets by the digest of their name:

```
run(f"SELECT id, name, md5_number_upper(name) % 4 FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 'hello', 1), (2, '', 0), (3, 'a', 0), (4, None, None)]
```

## 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_upper()` 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 value 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 a filter on `md5_number_upper()` shows the `FILTER` step above the scan:

```
plan(f"SELECT id FROM {TABLE} WHERE md5_number_upper(name) IS NOT NULL")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│   (CAST(CAST(array_slice  │
│ (CAST(CAST(md5_number(name│
│ ) AS BIT) AS VARCHAR), 65,│
│   []) AS BIT) AS UBIGINT) │
│        IS NOT NULL)       │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│            name           │
│             id            │
│                           │
└───────────────────────────┘
```

## Make it faster

- **Store the value if you filter or look rows up by it.** Compute it when you write the rows and keep it in a `UBIGINT` column. A comparison of that column with a constant is evaluated in VAST DataBase; `md5_number_upper(name) = ...` hashes every row in the Query Engine.

## Limitations and errors

- **Strings and bytes only.** Other types fail with `No function matches the given name and argument types`. The error names `md5_number` rather than `md5_number_upper`, and lists `md5_number(VARCHAR)` and `md5_number(BLOB)`. Cast a number or a `UUID` to `VARCHAR` first.
- **Not the top half of `md5_number`.** Despite the name, `md5_number_upper(x) * 2^64 + md5_number_lower(x)` is not `md5_number(x)`, and `md5_number(x) &gt;&gt; 64` is not `md5_number_upper(x)`. Use the bytes described in [What it does](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-upper#what-it-does).
- **Half of the digest.** 64 bits are enough for bucketing and checksums; for a key that must not collide across many rows, keep the full digest with [md5](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5) or [sha256](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-sha256).

```
run("SELECT md5_number_upper(DATE '2026-10-16')")
run("SELECT (md5_number('abc') >> 64)::UBIGINT = md5_number_upper('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;`: all 16 bytes as hex text | `VARCHAR` |
| [md5_number](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number) | `152195979970564155685860391459828531600`: all 16 bytes, little-endian, signed | `HUGEINT` |
| `md5_number_upper` | `12704604231530709392`: the first 8 bytes, little-endian | `UBIGINT` |
| [md5_number_lower](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-md5-number-lower) | `8250560606382298838`: the 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 hex(md5_number('abc')), hex(md5_number_upper('abc')), hex(md5_number_lower('abc'))")
```

```
[('900150983cd24fb0d6963f7d28e17f72', Decimal('152195979970564155685860391459828531600'), 12704604231530709392, 8250560606382298838)]
[('727FE1287D3F96D6B04FD23C98500190', 'B04FD23C98500190', '727FE1287D3F96D6')]
```

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.