---
title: "bar"
slug: "dev-database-reference-sql-functions-numeric-bar"
updated: 2026-10-30T18:18:51Z
published: 2026-10-30T18:18:51Z
canonical: "docs.vastdata.com/dev-database-reference-sql-functions-numeric-bar"
---

> ## 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.

# bar

*Applies to VAST Cluster 5.5.*

*[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Numeric and math functions](/develop/docs/dev-database-reference-sql-functions-numeric) › Number formatting.* Draws a bar of block characters whose length shows where a number lies between a minimum and a maximum, padded with spaces to a fixed width. Use it to chart a column in a query result.

## Syntax

```
bar(x, min, max)
bar(x, min, max, width)
```

| Argument | Type | Description |
| --- | --- | --- |
| `x` | `DOUBLE` (other numbers are converted) | The value to draw. |
| `min` | `DOUBLE` | The value drawn as an empty bar. |
| `max` | `DOUBLE` | The value drawn as a full bar. |
| `width` | `DOUBLE` | Optional. The length of the bar in characters, from 1 to 1000. The default is 80. |

**Returns:** `VARCHAR`.

## 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_numeric_bar`. 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 six team scores out of 10. 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_numeric_bar"'

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}.scores"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, team VARCHAR, score DOUBLE)")
run(f"INSERT INTO {TABLE} VALUES "
    "(1, 'Amber', 2.5), "
    "(2, 'Blue', 5.0), "
    "(3, 'Coral', 7.6), "
    "(4, 'Dune', 10.0), "
    "(5, 'Echo', 12.0), "
    "(6, NULL, NULL)")
```

```
[]
[]
[(6,)]
```

## What it does

`bar(x, min, max, width)` fills `width &#xd7; (x &#x2212; min) / (max &#x2212; min)` of the `width` characters with the full block `&#x2588;` (U+2588) and pads the rest with spaces, so the result is always `width` characters long. A partial cell is drawn with a narrower block, in eighths of a cell rounded down: `&#x258f;` (U+258F) for one eighth, `&#x258c;` (U+258C) for half a cell.

| Call | Result |
| --- | --- |
| `bar(5, 0, 10, 20)` | 10 full blocks, then 10 spaces |
| `bar(2.5, 0, 10, 20)` | 5 full blocks, then 15 spaces |
| `bar(2.6, 0, 10, 20)` | 5 full blocks, `&#x258f;` (5.2 cells), then 14 spaces |
| `bar(0, 0, 10, 20)` | 20 spaces |
| `bar(10, 0, 10, 20)` | 20 full blocks |
| `bar(5, 0, 10)` | 40 full blocks, then 40 spaces: the default width is 80 |

A value outside the range is drawn at the nearest end: above `max` gives a full bar, below `min` an empty one.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| A `NULL` value, minimum, maximum or width | `NULL` |
| `bar(15, 0, 10, 10)`, above `max` | 10 full blocks |
| `bar(-5, 0, 10, 10)`, below `min` | 10 spaces |
| `bar(5, 10, 0, 10)`, `min` above `max` | 10 spaces |
| `bar(5, 0, 0, 10)`, `min` equal to `max` and `x` above them | 10 full blocks |
| `bar(5, 5, 5, 10)`, `min`, `max` and `x` equal | 10 spaces |
| `bar(5, 0, 10, 1)` | `&#x258c;` (U+258C, half a cell) |
| `bar(5, 0, 10, 1.5)`, a fractional width | `&#x258a;` (U+258A), one character long |
| `bar(5, 0, 10, 1000)` | 1000 characters |
| NaN as `x`, or as `min` | spaces only |
| Infinity as `x` | a full bar |
| Infinity as `max` | spaces only |
| `bar(&apos;12&apos;, -5, 5, 20)`, a numeric string | converted: a full bar |
| A width below 1 | Error: `Max bar width must be &gt;= 1` |
| A width above 1000 | Error: `Max bar width must be &lt;= 1000` |
| `&apos;abc&apos;` | Error: `Could not convert string &apos;abc&apos; to DOUBLE` |
| A date, boolean, `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-numeric-bar#set-up-the-examples):

```
run("SELECT bar(NULL, 0, 10, 20), bar(5, NULL, 10), bar(5, 0, NULL), bar(5, 0, 10, NULL)")
run("SELECT bar(15, 0, 10, 10), bar(-5, 0, 10, 10), bar(5, 10, 0, 10), bar(5, 0, 0, 10), bar(5, 5, 5, 10)")
run("SELECT bar(5, 0, 10, 1), bar(5, 0, 10, 1.5), length(bar(5, 0, 10, 1.5)), length(bar(5, 0, 10, 1000))")
run("SELECT bar('nan'::DOUBLE, 0, 10, 10), bar(5, 'nan'::DOUBLE, 10, 10), bar('inf'::DOUBLE, 0, 10, 10), bar(5, 0, 'inf'::DOUBLE, 10)")
run(f"SELECT bar('12', -5, 5, 20) FROM {TABLE} LIMIT 1")
run("SELECT bar(5, 0, 10, 0)")
run("SELECT bar(5, 0, 10, 1001)")
run(f"SELECT bar('abc', -5, 5, 20) FROM {TABLE} LIMIT 1")
run(f"SELECT bar(DATE '2026-10-16', -5, 5, 20) FROM {TABLE} LIMIT 1")
```

```
[(None, None, None, None)]
[('██████████', '          ', '          ', '██████████', '          ')]
[('▌', '▊', 1, 1000)]
[('          ', '          ', '██████████', '          ')]
[('████████████████████',)]
OSError: Max bar width must be >= 1
OSError: Max bar width must be <= 1000
OSError: Could not convert string 'abc' to DOUBLE
InternalError: Binder Error: No function matches the given name and argument types 'bar(DATE, INTEGER_LITERAL, INTEGER_LITERAL, INTEGER_LITERAL)'. You might need to add explicit type casts.
```

The calls in [What it does](/develop/docs/dev-database-reference-sql-functions-numeric-bar#what-it-does):

```
run("SELECT bar(5, 0, 10, 20), bar(2.5, 0, 10, 20), bar(2.6, 0, 10, 20), bar(0, 0, 10, 20), bar(10, 0, 10, 20)")
run("SELECT length(bar(5, 0, 10)), length(bar(5, 0, 10, 20))")
```

```
[('██████████          ', '█████               ', '█████▏              ', '                    ', '████████████████████')]
[(80, 20)]
```

## Examples

A bar chart of the scores, 20 characters for a score of 10. `Echo`'s 12 is above the maximum and gets a full bar:

```
run(f"SELECT id, team, score, bar(score, 0, 10, 20) FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, 'Amber', 2.5, '█████               '), (2, 'Blue', 5.0, '██████████          '), (3, 'Coral', 7.6, '███████████████▏    '), (4, 'Dune', 10.0, '████████████████████'), (5, 'Echo', 12.0, '████████████████████'), (6, None, None, None)]
```

Only the teams that scored 5 or more. The condition is on the raw column:

```
run(f"SELECT id, team, bar(score, 0, 10, 20) FROM {TABLE} WHERE score >= 5 ORDER BY id LIMIT 10")
```

```
[(2, 'Blue', '██████████          '), (3, 'Coral', '███████████████▏    '), (4, 'Dune', '████████████████████'), (5, 'Echo', '████████████████████')]
```

## 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 `bar()` is always computed by the Query Engine:

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

The plan of the chart query has no `FILTER` step: the scan reads `score`, and the Query Engine draws the bars:

```
plan(f"SELECT team, bar(score, 0, 10, 20) FROM {TABLE}")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│            team           │
│bar(score, 0.0, 10.0, 20.0)│
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│            team           │
│           score           │
│                           │
└───────────────────────────┘
```

## Make it faster

- **Filter on the raw column.** `score &gt;= 5` is a comparison of a column with a constant, which is pushed down to VAST DataBase, so rows that don't match never leave storage, and `bar()` runs only on the rows that pass. Its plan has no `FILTER` step:

```
plan(f"SELECT team, bar(score, 0, 10, 20) FROM {TABLE} WHERE score >= 5")
```

```
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│            team           │
│bar(score, 0.0, 10.0, 20.0)│
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│           score           │
│            team           │
│                           │
└───────────────────────────┘
```

- **Don't filter on the bar.** A condition on `bar()` runs in a `FILTER` step; write the same condition on the number instead.

## Limitations and errors

- **Width from 1 to 1000.** A width below 1 fails with `Max bar width must be &gt;= 1`, and one above 1000 with `Max bar width must be &lt;= 1000`.
- **Numbers only.** A date, a boolean, a `BLOB` or a list fails with `No function matches the given name and argument types`. A string is converted to `DOUBLE`, and fails if it isn't a number: `Could not convert string &apos;abc&apos; to DOUBLE`.
- **No error for an odd range.** A reversed range, NaN or infinity gives an empty or a full bar, not an error. See [NULLs and edge cases](/develop/docs/dev-database-reference-sql-functions-numeric-bar#nulls-and-edge-cases).

## Similar functions

| Function | Use it to |
| --- | --- |
| `bar(x, min, max, width)` | draw one value as a bar of text: `bar(25, 0, 100, 20)` is 5 full blocks, then 15 spaces |
| [equi_width_bins](/develop/docs/dev-database-reference-sql-functions-numeric-equi-width-bins) | split a range into bins of equal width: `equi_width_bins(0, 100, 4, false)` is `[25, 50, 75, 100]` |

```
run("SELECT bar(25, 0, 100, 20), equi_width_bins(0, 100, 4, false)")
```

```
[('█████               ', [25, 50, 75, 100])]
```

Clean up:

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

```
[]
[]
```

## See also

- [Numeric and math functions](/develop/docs/dev-database-reference-sql-functions-numeric): all the numeric functions.
- [equi_width_bins](/develop/docs/dev-database-reference-sql-functions-numeric-equi-width-bins).
- [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.