---
title: "regexp_matches"
slug: "dev-database-reference-sql-functions-string-regexp-matches"
updated: 2026-10-30T18:18:56Z
published: 2026-10-30T18:18:56Z
canonical: "docs.vastdata.com/dev-database-reference-sql-functions-string-regexp-matches"
---

> ## 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.

# regexp_matches

*Applies to VAST Cluster 5.5.*

*[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Regular expressions](/develop/docs/dev-database-reference-sql-functions-string-regular-expressions) › Regular expressions.* `regexp_matches(s, pattern)` is true if the regular expression `pattern` matches **any part** of `s`. Anchor the pattern with `^` and `$` to test the whole string, or use [regexp_full_match](/develop/docs/dev-database-reference-sql-functions-string-regexp-full-match).

## Syntax

```
regexp_matches(s, pattern)
regexp_matches(s, pattern, options)
```

| Argument | Type | Description |
| --- | --- | --- |
| `s` | `VARCHAR` | The string to test. |
| `pattern` | `VARCHAR` | The regular expression ([syntax](/develop/docs/dev-database-reference-sql-functions-string-regexp-syntax)). A constant or a column. |
| `options` | `VARCHAR` | Optional, a constant. Flags such as `'i'` (ignore case), `'s'` (`.` matches a line break) or `'l'` (literal text); see [options](/develop/docs/dev-database-reference-sql-functions-string-regexp-syntax#what-it-does). |

**Returns:** `BOOLEAN`.

## 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_string_regexp_matches`. 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 five log lines. Line 4 is empty, and 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_string_regexp_matches"'

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}.logs"
run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}")
run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, line VARCHAR)")
run(f"INSERT INTO {TABLE} VALUES "
    "(1, 'ERROR 2026-10-16 disk full'), "
    "(2, 'warn: Disk 93% full'), "
    "(3, 'INFO 2026-10-17 ok'), "
    "(4, ''), "
    "(5, NULL)")
```

```
[]
[]
[(5,)]
```

## What it does

`regexp_matches` searches `s` for the first place where `pattern` matches, and returns `true` if there is one:

| Call | Result | Why |
| --- | --- | --- |
| `regexp_matches(&apos;abc&apos;, &apos;b&apos;)` | `true` | `b` matches in the middle |
| `regexp_matches(&apos;abc&apos;, &apos;^b&apos;)` | `false` | `^` anchors the pattern at the start |
| `regexp_matches(&apos;abc&apos;, &apos;^abc&#x24;&apos;)` | `true` | anchored at both ends: the whole string |
| `regexp_matches(&apos;ABC&apos;, &apos;b&apos;, &apos;i&apos;)` | `true` | option `i` ignores case |
| `regexp_matches(&apos;axb&apos;, &apos;a.b&apos;, &apos;l&apos;)` | `false` | option `l`: the pattern is literal text |

The pattern syntax and the options are described on [Regular-expression syntax and options](/develop/docs/dev-database-reference-sql-functions-string-regexp-syntax). A `.` matches one code point, so `e` followed by a combining accent (U+0301) needs `..`, and `&apos;cafe\u0301&apos;` doesn't match `&apos;&#xe9;&#x24;&apos;`.

## NULLs and edge cases

| Input | Result |
| --- | --- |
| A `NULL` string or pattern | `NULL` |
| A `NULL` options string | Error: `Regex options field must not be NULL` |
| An empty pattern: `regexp_matches(&apos;abc&apos;, &apos;&apos;)`, `regexp_matches(&apos;&apos;, &apos;&apos;)` | `true` |
| `regexp_matches(&apos;&apos;, &apos;.&apos;)` | `false` |
| `regexp_matches(&apos;ABC&apos;, &apos;b&apos;, &apos;ic&apos;)` (the last of `i` and `c` wins) | `false` |
| `regexp_matches(&apos;abc&apos;, &apos;b&apos;, &apos;g&apos;)` | Error: `Option &apos;g&apos; (global replace) is only valid for regexp_replace` |
| An invalid constant pattern: `regexp_matches(&apos;abc&apos;, &apos;(&apos;)` | Error: `missing ): (` |
| A number, date, boolean, `BLOB` or list | Error: `No function matches the given name and argument types`, for example `&apos;regexp_matches(INTEGER_LITERAL, STRING_LITERAL)&apos;` |

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-string-regexp-matches#set-up-the-examples):

```
run("SELECT regexp_matches(NULL, 'a'), regexp_matches('abc', NULL), regexp_matches('abc', ''), "
    "regexp_matches('', ''), regexp_matches('', '.'), regexp_matches('ABC', 'b', 'ic')")
run("SELECT regexp_matches('abc', 'b', NULL)")
run("SELECT regexp_matches('abc', 'b', 'g')")
run("SELECT regexp_matches('abc', '(')")
run("SELECT regexp_matches(123, '1')")
```

```
[(None, None, True, True, False, False)]
InternalError: Invalid Input Error: Regex options field must not be NULL
InternalError: Invalid Input Error: Option 'g' (global replace) is only valid for regexp_replace
InternalError: Invalid Input Error: missing ): (
InternalError: Binder Error: No function matches the given name and argument types 'regexp_matches(INTEGER_LITERAL, STRING_LITERAL)'. You might need to add explicit type casts.
```

## Examples

Which lines hold a date, which mention a disk in any case, and which start with an upper-case word followed by a space:

```
run(f"SELECT id, regexp_matches(line, '\\d{{4}}-\\d{{2}}-\\d{{2}}'), regexp_matches(line, 'disk', 'i'), "
    f"regexp_matches(line, '^[A-Z]+ ') FROM {TABLE} ORDER BY id LIMIT 10")
```

```
[(1, True, True, True), (2, False, True, False), (3, True, False, True), (4, False, False, False), (5, None, None, None)]
```

Keep only the error and warning lines, in any case:

```
run(f"SELECT id, line FROM {TABLE} WHERE regexp_matches(line, '^(error|warn)', 'i') ORDER BY id LIMIT 10")
```

```
[(1, 'ERROR 2026-10-16 disk full'), (2, 'warn: Disk 93% full')]
```

## 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`). In `WHERE`, the Query Engine first rewrites simple patterns into cheaper tests:

| Pattern | Becomes | Runs in |
| --- | --- | --- |
| `&apos;^literal&#x24;&apos;` (the whole string, no special characters) | `line = &apos;literal&apos;` | VAST DataBase (pushed down; no `FILTER` step) |
| `&apos;^literal&apos;` | `prefix(line, &apos;literal&apos;)` | a `FILTER` step in the Query Engine |
| `&apos;literal&#x24;&apos;` | `suffix(line, &apos;literal&apos;)` | a `FILTER` step |
| `&apos;literal&apos;` | `contains(line, &apos;literal&apos;)` | a `FILTER` step |
| anything else, with option `i`, or from a column | `regexp_matches(...)` | a `FILTER` step |

In a `FILTER` step, the scan sends the column for every row and the Query Engine keeps the rows that match. In the `SELECT` list, `regexp_matches` is computed for each row the scan returns. The plans of a whole-string pattern, a prefix and a general pattern:

```
plan(f"SELECT id FROM {TABLE} WHERE regexp_matches(line, '^INFO 2026-10-17 ok$')")
plan(f"SELECT id FROM {TABLE} WHERE regexp_matches(line, '^ERROR')")
plan(f"SELECT id FROM {TABLE} WHERE regexp_matches(line, '\\d{{4}}-\\d{{2}}')")
```

```
┌───────────────────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│      Projections: id      │
│                           │
└───────────────────────────┘
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│   prefix(line, 'ERROR')   │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│            line           │
│             id            │
│                           │
└───────────────────────────┘
┌───────────────────────────┐
│         PROJECTION        │
│    ────────────────────   │
│             #1            │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│           FILTER          │
│    ────────────────────   │
│   regexp_matches(line, '  │
│       \d{4}-\d{2}')       │
│                           │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│         VAST_SCAN         │
│    ────────────────────   │
│    Function: VAST_SCAN    │
│                           │
│        Projections:       │
│            line           │
│             id            │
│                           │
└───────────────────────────┘
```

## Make it faster

- **Prefer a literal or anchored pattern.** `&apos;^ERROR&apos;` runs as `prefix()` and `&apos;disk&apos;` as `contains()`, which are cheaper than a general pattern. A whole-string literal is pushed down.
- **Use a range instead of a prefix.** `line &gt;= &apos;ERROR&apos; AND line &lt; &apos;ERROS&apos;` selects the lines that start with `ERROR`, and it's pushed down to VAST DataBase; `regexp_matches(line, &apos;^ERROR&apos;)` isn't. The plan has no `FILTER` step:

```
plan(f"SELECT id FROM {TABLE} WHERE line >= 'ERROR' AND line < 'ERROS'")
```

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

- **Combine it with a pushed-down condition.** In `id &gt; 100 AND regexp_matches(line, &apos;disk&apos;)`, `id &gt; 100` is still evaluated in VAST DataBase, so the pattern runs only on the rows that pass it.
- **Extract at load time.** If you filter on a part of the line often, such as the level, store it in its own column with [regexp_extract](/develop/docs/dev-database-reference-sql-functions-string-regexp-extract) when you write the data.

## Limitations and errors

- **Strings only.** A number, date, boolean, `BLOB` or list fails with `No function matches the given name and argument types`. Cast the value to `VARCHAR` first.
- **The options string is a constant and isn't `NULL`.** From a column it fails with `Regex options field must be a constant`; `NULL` fails with `Regex options field must not be NULL`.
- **A pattern from a column is checked row by row.** One invalid value fails the query with the reason, such as `missing ): l+(` or `trailing \`.
- **Some pattern features aren't available,** such as backreferences and lookahead: see [syntax and options](/develop/docs/dev-database-reference-sql-functions-string-regexp-syntax#limitations-and-errors).
- **Other dialects' names aren't available.** `regexp_like` and `rlike` fail with `Scalar Function with name ... does not exist!`; `s REGEXP p` and `s RLIKE p` fail with a syntax error. Use `regexp_matches`.

```
run(f"SELECT regexp_matches(line, 'a', CAST(id AS VARCHAR)) FROM {TABLE} LIMIT 1")
run("SELECT regexp_like('abc', 'b')")
run("SELECT 'abc' REGEXP 'b'")
```

```
InternalError: Invalid Input Error: Regex options field must be a constant
InternalError: Catalog Error: Scalar Function with name regexp_like does not exist!
InternalError: Parse query: 'SELECT 'abc' REGEXP 'b'' failed with: Parser Error: syntax error at or near "'b'"
```

## Similar functions

| Function | Tests | Result for `&apos;xabcx&apos;` and `abc` |
| --- | --- | --- |
| `regexp_matches(&apos;xabcx&apos;, &apos;abc&apos;)` | a regular expression, anywhere | `true` |
| [regexp_full_match](/develop/docs/dev-database-reference-sql-functions-string-regexp-full-match)`(&apos;xabcx&apos;, &apos;abc&apos;)`, `~` | a regular expression, the whole string | `false` |
| [SIMILAR TO](/develop/docs/dev-database-reference-sql-functions-string-similar-to) `&apos;abc&apos;` | a regular expression, the whole string | `false` |
| [LIKE](/develop/docs/dev-database-reference-sql-functions-string-like) `&apos;%abc%&apos;` | `%` and `_` wildcards, the whole string | `true` |
| [contains](/develop/docs/dev-database-reference-sql-functions-string-contains)`(&apos;xabcx&apos;, &apos;abc&apos;)` | plain text, anywhere | `true` |

```
run("SELECT regexp_matches('xabcx', 'abc'), regexp_full_match('xabcx', 'abc'), 'xabcx' ~ 'abc', "
    "'xabcx' SIMILAR TO 'abc', 'xabcx' LIKE '%abc%', contains('xabcx', 'abc')")
```

```
[(True, False, False, False, True, True)]
```

Clean up:

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

```
[]
[]
```

## See also

- [Regular-expression syntax and options](/develop/docs/dev-database-reference-sql-functions-string-regexp-syntax).
- [Regular expressions](/develop/docs/dev-database-reference-sql-functions-string-regular-expressions): all the regular-expression functions.
- [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.