pg_re2 Postgres Extension
=========================

[![PGXN version](https://badge.fury.io/pg/pg_re2.svg)](https://badge.fury.io/pg/pg_re2)
[![Build Status](https://github.com/ClickHouse/pg_re2/actions/workflows/ci.yml/badge.svg)](https://github.com/ClickHouse/pg_re2/actions/workflows/ci.yml)

This library contains a single PostgreSQL extension, `re2`, which provides
[ClickHouse]-compatible [regular expression functions] powered by [re2]:

``` psql
try=# create extension re2;
CREATE EXTENSION

try=# SELECT re2match('hello world', 'h.*o');
 re2match 
----------
 t
(1 row)
```

Building
--------

To build pg_re2, install the [re2] library then just do this:

``` sh
make
make installcheck
make install
```

If you encounter an error such as:

```
"Makefile", line 8: Need an operator
```

You need to use GNU make, which may well be installed on your system as
`gmake`:

``` sh
gmake
gmake install
gmake installcheck
```

If you encounter an error such as:

```
make: pg_config: Command not found
```

Be sure that you have `pg_config` installed and in your path. If you used a
package management system such as RPM to install PostgreSQL, be sure that the
`-devel` package is also installed. If necessary tell the build process where
to find it:

``` sh
env PG_CONFIG=/path/to/pg_config make && make installcheck && make install
```

If you counter an error such as:

```
src/re2_wrapper.cpp:14:10: fatal error: 're2/re2.h' file not found
```

You either need to install [re2] or tell the compiler where to find it.
If, for example, you installed the [Homebrew re2], try:

``` sh
make CPPFLAGS=-I/opt/homebrew/include \
     CFLAGS=-I/opt/homebrew/include \
     LDFLAGS=-L/opt/homebrew/lib
```

If you encounter an error such as:

```
ERROR:  must be owner of database regression
```

You need to run the test suite using a super user, such as the default
"postgres" super user:

``` sh
make installcheck PGUSER=postgres
```

To install the extension in a custom prefix on PostgreSQL 18 or later, pass
the `prefix` argument to `install` (but no other `make` targets):

```sh
make install prefix=/usr/local/extras
```

Then ensure that the prefix is included in the following [`postgresql.conf`
parameters]:

```ini
extension_control_path = '/usr/local/extras/postgresql/share:$system'
dynamic_library_path   = '/usr/local/extras/postgresql/lib:$libdir'
```

Usage
-----

Once re2 is installed, you can add it to a database by connecting to a
database as a super user and running:

``` sql
CREATE EXTENSION re2;
```

If you want to install re2 and all of its supporting objects into a specific
schema, use the `SCHEMA` clause to specify the schema, like so:

``` sql
CREATE SCHEMA env;
CREATE EXTENSION re2 SCHEMA env;
```

Dependencies
------------

The `re2` extension requires PostgreSQL 16 or higher, [re2], and the C
standard library, `<stdlib.h>`.

Copyright and License
---------------------

Copyright (c) 2026 ClickHouse

This module is free software; you can redistribute it and/or modify it under
the [PostgreSQL License](http://www.opensource.org/licenses/postgresql).

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose, without fee, and without a written agreement is
hereby granted, provided that the above copyright notice and this paragraph
and the following two paragraphs appear in all copies.

In no event shall ClickHouse be liable to any party for direct, indirect,
special, incidental, or consequential damages, including lost profits, arising
out of the use of this software and its documentation, even if ClickHouse has
been advised of the possibility of such damage.

ClickHouse specifically disclaim any warranties, including, but not limited
to, the implied warranties of merchantability and fitness for a particular
purpose. The software provided hereunder is on an "as is" basis, and
ClickHouse have no obligations to provide maintenance, support, updates,
enhancements, or modifications.

  [ClickHouse]: https://clickhouse.com/clickhouse "ClickHouse: The fastest open-source analytical database"
  [re2]: https://github.com/google/re2 "RE2, a regular expression library"
  [regular expression functions]: https://clickhouse.com/docs/sql-reference/functions/string-search-functions
    "ClickHouse Docs: Functions for Searching in Strings"
  [Homebrew re2]: https://formulae.brew.sh/formula/re2
  [`postgresql.conf` parameters]: https://www.postgresql.org/docs/devel/runtime-config-client.html#RUNTIME-CONFIG-CLIENT-OTHER