---
title: "UPDATE"
slug: "dev-database-reference-sql-update"
updated: 2026-10-30T18:19:11Z
published: 2026-10-30T18:19:11Z
canonical: "docs.vastdata.com/dev-database-reference-sql-update"
---

> ## 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.

# UPDATE

*Applies to VAST Cluster 5.5.*

Changes column values in the rows that match a condition.

## Syntax

```
UPDATE "<bucket>/<schema>".<table>
SET <column> = <expression> [, <column> = <expression> ...]
WHERE <condition>
```

## Parameters and rules

| Part | Meaning |
| --- | --- |
| `SET &lt;column&gt; = &lt;expression&gt;` | The new value. It can be a constant, or an expression on the row's own columns, such as `temperature + 1` or `list_append(tags, 7)`. |
| `WHERE &lt;condition&gt;` | Which rows to change. Any condition that works in a [SELECT](/develop/docs/dev-database-reference-sql-select) on one table works here. |

- The statement returns one row with one column, `Count`: the number of rows changed.
- The new values can come only from the row itself. `UPDATE ... FROM &lt;other table&gt;` needs a join, and fails.
- On a sorted table, you can't change a sort column to a new value: the statement fails with `Invalid Argument` ([updates and deletes](/develop/docs/dev-database-guides-updates-and-deletes#vast-query-engine)). Other columns can be updated.
- On a vector-indexed table, you can't update the vector column. Delete the row and insert it again ([vector search SQL](/develop/docs/dev-database-reference-sql-vector-search)).
- The Query Engine can't update a partitioned table ([not supported](/develop/docs/dev-database-reference-sql-not-supported)).

## What happens on the cluster

The Query Engine finds the rows that match `WHERE`, computes the new values, and writes them on the cluster. The same [rules](/develop/docs/dev-database-reference-sql-select#where-filters-run) decide whether the `WHERE` conditions are evaluated in VAST DataBase or in the Query Engine. Only the count comes back. For what an update does to the stored data, see [write path](/develop/docs/dev-database-concepts-architecture-write-path#updates).

## Example

The examples use the `run()` helper and the environment variables described in the [SQL reference](/develop/docs/dev-database-reference-sql-index#example-connect-and-use-a-transaction). This block connects, and creates the schema `docs_sql_update` with three rows:

```
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_update"'

def connect(autocommit=True):
    return 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=autocommit,
    )

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)

conn = connect()
TABLE = f"{SCHEMA}.readings"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, city VARCHAR, temperature DOUBLE, tags INTEGER[])")
run(f"INSERT INTO {TABLE} VALUES (1, 'Lisbon', 21.5, [1]), (2, 'Oslo', 4.0, []), (3, 'Cairo', 30.2, [2, 3])")
```

```
[]
[]
[(3,)]
```

Set a constant, compute from the row, and append to a list:

```
run(f"UPDATE {TABLE} SET city = 'Lisboa' WHERE id = 1")
run(f"UPDATE {TABLE} SET temperature = temperature + 1 WHERE temperature < 25")
run(f"UPDATE {TABLE} SET tags = list_append(tags, 9) WHERE city LIKE 'C%'")
run(f"SELECT id, city, temperature, tags FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1,)]
[(2,)]
[(1,)]
[(1, 'Lisboa', 22.5, [1]), (2, 'Oslo', 5.0, []), (3, 'Cairo', 30.2, [2, 3, 9])]
```

Taking values from another table fails:

```
run(f"CREATE TABLE IF NOT EXISTS {SCHEMA}.names (id BIGINT, city VARCHAR)")
run(f"UPDATE {TABLE} SET city = n.city FROM {SCHEMA}.names n WHERE readings.id = n.id")
```

```
[]
InternalError: The operator 'HASH_JOIN' type=32 is currently not supported.
```

Clean up:

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

```
[]
[]
[]
```

## Errors

| You wrote | Message |
| --- | --- |
| `UPDATE ... FROM &lt;table&gt;` | `InternalError: The operator &apos;HASH_JOIN&apos; type=32 is currently not supported.` |
| A new value in a sort column | `Invalid Argument` ([updates and deletes](/develop/docs/dev-database-guides-updates-and-deletes#vast-query-engine)) |
| A new value in an indexed vector column | `Invalid Argument` ([vector search SQL](/develop/docs/dev-vector-search-reference-sql#errors-youll-see)) |

## Trino and Spark

Trino and Spark update with their own `UPDATE` statements, and Trino also has `MERGE`; their `WHERE` can use anything the engine evaluates. See [updates and deletes](/develop/docs/dev-database-guides-updates-and-deletes#update-and-delete-with-trino-spark-or-the-vast-query-engine).

See also: [DELETE and TRUNCATE](/develop/docs/dev-database-reference-sql-delete), [updates and deletes](/develop/docs/dev-database-guides-updates-and-deletes).