---
pg_extension_name: pg_text_semver
pg_extension_version: 1.2.0
pg_readme_generated_at: 2024-03-07 15:49:02.462683+00
pg_readme_version: 0.6.6
---

# PostgreSQL semantic versioning extension: `pg_text_semver`

[![PGXN version](https://badge.fury.io/pg/pg_text_semver.svg)](https://badge.fury.io/pg/pg_text_semver)

This is [not the only](#alternatives-to-pg_text_semver) Postgres extension that
implements the [Semantic Versioning 2.0.0
Specification](https://semver.org/spec/v2.0.0.html); what sets this one apart
is that offers a simple `semver` `DOMAIN` based on Postgres'
built-in `text` type.

## `pg_text_semver` features

* Values of the [`semver`](#domain-semver) domain type can be compared:
  - using the usual comparison operators—`<`, '>`, `<=`, `>=`, `<>`, `!=`, and
    `=`—; or
  - using the [`semver_cmp(semver, semver)`](#function-semver_cmp-semver-semver)
    function directly.
* The [`semver`](#domain-semver) domain is constrained using the
  [`semver_regexp()`](#function-semver_regexp-boolean) function.  This means
  that you can also access this regular expression directly, either with
  capturing groups or without, by passing `true` or `false` to the function,
  respectively.
* Parsed `semver` values can be obtained by casting to the `semver_parsed`
  composite type.
* All the same comparison operators and functions exist for `semver_parsed` as
  do for plain `semver` values.
* In addition, `semver_parsed` values can be used for sorting and indexing.
* `semver_parsed` values can be serialized to a properly formatted semantic
  version by casting (back) to `semver` or `text`.
* There's a separate [`semver_prerelease`](#domain-semver_prerelease) domain
  type, so that the prerelease portions of semantic versions can be validated
  or compared (using the
  [`semver_prerelease_cmp()`](#function-semver_prerelease_cmp-semver_prerelease-semver_prerelease)
  function.

## Installation

Basically:

```
sudo make install
```

Like most Postgres extensions, `pg_text_semver` requires [Postgres' PGXS build
infrastructure](https://www.postgresql.org/docs/current/extend-pgxs.html) for
`make install` to work.  Depending on your OS, this may or may not require
you to install anything in addition to the package you need to install to get
the `postgres` daemon up and running.

## `pg_text_semver` usage

See the [`test__pg_text_semver()`](#procedure-test__pg_text_semver) procedure
for examples of how to use the types, operators and functions provides by this
extension.

## Alternatives to `pg_text_semver`

An excellent pre-existing alternative to `pg_text_semver` is the
[`semver`](https://github.com/theory/pg-semver) extension.  `semver` is written
in C and therefore more efficient than `pg_text_semver`.  But, as of March 2,
2023, [it treats the parts of the semantic version as 32-bit
integers](https://github.com/theory/pg-semver/issues/47), while the spec
prescribes no limitations to the size of each number.

Besides [`semver`](https://github.com/theory/pg-semver) (repo name `pg-semver`,
with a dash), there is also the older [PG
SEMVER](https://github.com/eendroroy/pg_semver) (repo name `pg_semver`, with an
underscore).  The `pg_text_semver` author only discovered PG SEMVER _after_
releasing his own extension, and hasn't tried it; something left to do…

## Object reference

### Routines

#### Function: `max (semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `semver`

Function attributes: `IMMUTABLE`, COST 1

#### Function: `meta_pgxn_version_range_cmp (text, text)`

Use this function if you want to check a version (semantic or otherwise) against a PGXN `META.json` Version Ranges.

This function takes 2 arguments:

1. a [Version Ranges](https://pgxn.org/spec/#Version.Ranges) string confirmed to
   PGXN's `META.json` spec; and
2. a version string to tests against the Version Ranges;

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `text`                                                               |  |
|   `$2` |       `IN` |                                                                   | `text`                                                               |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `RETURNS NULL ON NULL INPUT`, `PARALLEL SAFE`

#### Function: `meta_pgxn_version_range (text)`

Returns a row for each element from a _Version Ranges_ value that adheres to the PGXN `META.json` spec.

When dealing with [version ranges](https://pgxn.org/spec/#Version.Ranges) from
a PGXN `META.json` file, it may be convenient to parse these out so that the
constraints can then, for example be fed into [`semver_cmp(semver, semver,
text)`](#function-semver_cmp-semver-semver-text).

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` | ``                                                                | `text`                                                               |  |
|   `$2` |    `TABLE` | `version_range_op`                                                | `text`                                                               |  |
|   `$3` |    `TABLE` | `version_no`                                                      | `text`                                                               |  |
|   `$4` |    `TABLE` | `any_version`                                                     | `boolean`                                                            |  |

Function return type: `TABLE(version_range_op text, version_no text, any_version boolean)`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`, ROWS 1000

#### Function: `min (semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `semver`

Function attributes: `IMMUTABLE`, COST 1

#### Function: `nonsemver_cmp (text, text, text)`

When we don't know the semantics of two version strings, it's hard to compare them for anything else than equality.  But, in case you do want to do that, there's this function.

The first two function arguments are the versions to compare.  The third
argument must be an unequality operator (`'='` or `'=='`) or an unequality
operator (`'!='` or `'<>'`).

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `text`                                                               |  |
|   `$2` |       `IN` |                                                                   | `text`                                                               |  |
|   `$3` |       `IN` |                                                                   | `text`                                                               |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `RETURNS NULL ON NULL INPUT`, `PARALLEL SAFE`

#### Function: `pg_text_semver_meta_pgxn()`

Returns the JSON meta data that has to go into the `META.json` file needed for PGXN—PostgreSQL Extension Network—packages.

The `Makefile` includes a recipe to allow the developer to: `make META.json` to
refresh the meta file with the function's current output, including the
`default_version`.

And indeed, `pg_safer_settings` can be found on PGXN:
https://pgxn.org/dist/pg_safer_settings/

Function return type: `jsonb`

Function attributes: `STABLE`

#### Function: `pg_text_semver_readme()`

This function utilizes the `pg_readme` extension to generate a thorough README for this extension, based on the `pg_catalog` and the `COMMENT` objects found therein.

Function return type: `text`

Function-local settings:

  *  `SET search_path TO ext, pg_temp`
  *  `SET pg_readme.include_view_definitions TO true`
  *  `SET pg_readme.include_routine_definitions_like TO {test__%}`

#### Function: `semver_cmp (semver_parsed, semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |
|   `$2` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `integer`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_cmp (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `integer`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_cmp (semver, semver, text)`

This function is convenient if you want to compare two versions, and want to dynamically give the comparison operator as a third argument rather than hardcoding the call to a specific comparison operator (function).

Both the SQL notation and non-SQL notation of some operators are supported, to
be at least flexible enough to, for instance, support testing [version
range](https://pgxn.org/spec/#Version.Ranges) constraints according to the PGXN
spec.

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$3` |       `IN` |                                                                   | `text`                                                               |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_eq (semver_parsed, semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |
|   `$2` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_eq (semver, semver)`

This functions returns true if two semantic versions are _semantically_ identical to each other, false otherwise.

This is the only function in the `semver_<op>(semver, semver)` family that does
not utilize `semver_cmp(semver, semver)`.  Whether that one extra level of
indirection would indeed hinder performance remains to be tested, as of March
2, 2024.

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_ge (semver_parsed, semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |
|   `$2` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_ge (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_greatest (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `semver`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_gt (semver_parsed, semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |
|   `$2` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_gt (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_least (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `semver`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_le (semver_parsed, semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |
|   `$2` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_le (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_lt (semver_parsed, semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |
|   `$2` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_lt (semver, semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |
|   `$2` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_parsed (semver)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver`                                                             |  |

Function return type: `semver_parsed`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_parsed (text)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `text`                                                               |  |

Function return type: `semver_parsed`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_cmp (semver_prerelease, semver_prerelease)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |
|   `$2` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |

Function return type: `integer`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_eq (semver_prerelease, semver_prerelease)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |
|   `$2` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_ge (semver_prerelease, semver_prerelease)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |
|   `$2` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_gt (semver_prerelease, semver_prerelease)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |
|   `$2` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_le (semver_prerelease, semver_prerelease)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |
|   `$2` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_lt (semver_prerelease, semver_prerelease)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |
|   `$2` |       `IN` |                                                                   | `semver_prerelease`                                                  |  |

Function return type: `boolean`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_prerelease_regexp()`

Function return type: `text`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver_regexp (boolean)`

Returns a regular expression to match or parse a semantic version string.

The regular expression is based on the official regular expression from [semver.or](https://semver.org/).

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` | `with_capture_groups$`                                            | `boolean`                                                            | `false` |

Function return type: `text`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Function: `semver (semver_parsed)`

Function arguments:

| Arg. # | Arg. mode  | Argument name                                                     | Argument type                                                        | Default expression  |
| ------ | ---------- | ----------------------------------------------------------------- | -------------------------------------------------------------------- | ------------------- |
|   `$1` |       `IN` |                                                                   | `semver_parsed`                                                      |  |

Function return type: `semver`

Function attributes: `IMMUTABLE`, `LEAKPROOF`, `PARALLEL SAFE`

#### Procedure: `test__pg_text_semver()`

Procedure-local settings:

  *  `SET search_path TO pg_catalog`
  *  `SET plpgsql.check_asserts TO true`
  *  `SET pg_readme.include_this_routine_definition TO true`

```sql
CREATE OR REPLACE PROCEDURE ext.test__pg_text_semver()
 LANGUAGE plpgsql
 SET search_path TO 'pg_catalog'
 SET "plpgsql.check_asserts" TO 'true'
 SET "pg_readme.include_this_routine_definition" TO 'true'
AS $procedure$
begin
    -- Because this extension is relocatable, let's update the search_path to include the extensions current
    -- schema (which we couldn't have done by `SET search_path TO CURRENT` in the extension setup script.
    perform
        set_config('search_path', e.extnamespace::regnamespace::text || ', pg_catalog', true)
    from
        pg_extension as e
    where
        e.extname = 'pg_text_semver'
    ;

    -- Remember the buildup of a semver: <major>.<minor>.<patch>-<prerelease>+<build>

    -- We can validate the prerelease portion of a semantic version separately:
    assert 'alpha-1' ~ semver_prerelease_regexp();
    assert '0123' !~ semver_prerelease_regexp(), '0 may NOT lead in a numeric prerelease identifer.';
    assert '0something' ~ semver_prerelease_regexp(), '0 MAY lead in an ALPHAnumeric prerelease identifer.';

    -- Or we can use the domain that uses that regexp in its check constraint:
    perform 'alpha-1'::semver_prerelease;
    perform 'alpha28743'::semver_prerelease;
    perform '0.1.a.a1-.99-e'::semver_prerelease;
    perform 'a1.99-e-'::semver_prerelease;
    perform null::semver_prerelease, 'A prerelease tag is not a mandatory part of a semantic version.';

    --
    -- The prerelease parts of semantic versions can be separately compared:

    assert semver_prerelease_cmp(null, 'beta') = 1;
    assert null::semver_prerelease > 'beta'::semver_prerelease;

    assert semver_prerelease_cmp(null, null) = 0;
    assert null::semver_prerelease = null::semver_prerelease, 'Missing prerelease tags should count equally.';

    assert semver_prerelease_cmp('same', 'same') = 0;
    assert 'same'::semver_prerelease = 'same'::semver_prerelease;
    assert 's.4.m.e'::semver_prerelease = 's.4.m.e'::semver_prerelease;

    assert semver_prerelease_cmp('alpha', null) = -1;
    assert 'alpha'::semver_prerelease < null::semver_prerelease;

    assert semver_prerelease_cmp('string.180', 'string.20') = 1;
    assert 'string.180'::semver_prerelease > 'string.20'::semver_prerelease;

    assert semver_prerelease_cmp('has.3.identifiers', 'has.3.identifiers.plus-1') = -1;
    assert 'has.3.identifiers'::semver_prerelease < 'has.3.identifiers.plus-1'::semver_prerelease;

    assert semver_prerelease_cmp('0.1.2.3.4', '0.1.2.3.4') = 0;
    assert '0.1.2.3.4'::semver_prerelease = '0.1.2.3.4'::semver_prerelease;

    assert semver_prerelease_cmp('0.1.2.3.4.5', '0.1.2.3.4') = 1;
    assert '0.1.2.3.4.5'::semver_prerelease > '0.1.2.3.4'::semver_prerelease;

    --
    -- The `semvver_parsed` type and accompanying functions are used by the `semver` comparison functions,
    -- so we test the former first because we want to test from the deepest dependency up, which is also
    -- why we _started_ by testing the `semver_prerelease` domain and its associated functions.
    --

    -- We cast to `jsonb` here to bypass `semver_parsed` its very own equality operator.
    assert to_jsonb(semver_parsed('1.0.0')) = to_jsonb(row('1', '0', '0', null, null)::semver_parsed);
    assert to_jsonb(semver_parsed('8.4.7-alpha')) = to_jsonb(row('8', '4', '7', 'alpha', null)::semver_parsed);
    assert to_jsonb(semver_parsed('1.0.0+commit-x')) = to_jsonb(row('1', '0', '0', null, 'commit-x')::semver_parsed);
    assert to_jsonb(semver_parsed('1.0.0-a.1+commit-y')) = to_jsonb(row('1', '0', '0', 'a.1', 'commit-y')::semver_parsed);

    -- Semantic versions can be constructed from a composite by casting to `text`.
    assert row('1', '0', '0', null, null)::semver_parsed::text = '1.0.0';
    -- Or by casting to `semver` (a `text` `DOMAIN`):
    assert row('1', '0', '0', null, null)::semver_parsed::semver = '1.0.0';
    -- When we cast to `semver`, validation is implicit:
    begin
        perform row('l', '0', 'l', null, null)::semver_parsed::semver;
        raise assert_failure using message = 'l.0.l should not be accepted as a valid semver.';
    exception when check_violation then
    end;

    -- `semver_parsed` can be ordered semantically.
    declare
        _presorted text[] = array[
            '0.0.9'
            ,'0.0.88-alpha-2-a'
            ,'0.0.88+stuff'
            ,'0.0.88'
            ,'1.0.0-a'
            ,'1.0.0-a.123'
            ,'1.0.0'
        ];
        _shuffled text[] = array[
            '0.0.88-alpha-2-a'
            ,'0.0.88'
            ,'0.0.9'
            ,'1.0.0'
            ,'1.0.0-a.123'
            ,'1.0.0-a'
            ,'0.0.88+stuff'
        ];
        _resorted text[] = (select array_agg(v order by v::semver_parsed) from unnest(_shuffled) as v);
    begin
        assert _resorted = _presorted, format('%s ≠ %s', _resorted, _presorted);
    end;

    assert '0.9.3'::semver < '0.11.2'::semver;
    assert '10.0.0'::semver > '2.9.9'::semver;

    assert '1.0.0-alpha'::semver < '1.0.0'::semver;
    assert '1.0.0-alpha'::semver < '1.0.0-alpha.2'::semver;
    assert '1.0.0-alpha.1'::semver < '1.0.0-alpha.2'::semver;
    assert '1.0.0-alpha.1'::semver < '1.0.0-alpha.a'::semver;
    assert '1.0.0-alpha'::semver < '1.0.0-beta'::semver;

    assert '8.8.8+bla'::semver = '8.8.8'::semver,
        '“Build metadata MUST be ignored when determining version precedence.”';
    assert '8.8.8+bla'::semver = '8.8.8+bah'::semver,
        '“Build metadata MUST be ignored when determining version precedence.”';
    assert '8.8.8-alpha+build12'::semver = '8.8.8-alpha+build13'::semver,
        '“Build metadata MUST be ignored when determining version precedence.”';
    assert '8.8.8-alpha+build12'::semver = '8.8.8-alpha'::semver;

    -- Unlike `semver_parsed`, plain `semver` cannot be ordered semantically; because `semver` is a `text`
    -- domain, it will be sorted lexically as such.  _But_, we can always cast to `semver_parsed` for
    -- ordering and indexing.  Do remember to index on that cast expression then, or your queries will be
    -- slow!
    declare
        _presorted text[] := array[
            '0.0.9'
            ,'0.0.88-alpha-2-a'
            ,'0.0.88+stuff'
            ,'0.0.88'
            ,'1.0.0-a'
            ,'1.0.0-a.123'
            ,'1.0.0'
        ];
        _shuffled text[] := array[
            '0.0.88-alpha-2-a'
            ,'0.0.88'
            ,'0.0.9'
            ,'1.0.0'
            ,'1.0.0-a.123'
            ,'1.0.0-a'
            ,'0.0.88+stuff'
        ];
        _resorted text[];
    begin
        create temporary table shuffled (v semver);
        insert into shuffled select v from unnest(_shuffled) as v;
        --create index on shuffled (v text_semver_ops);  -- Operator classes for domains are ignored.
        create index on shuffled ((v::semver_parsed));
        _resorted := (select array_agg(v order by v::semver_parsed) from shuffled);
        assert _resorted = _presorted, format('%s ≠ %s', _resorted, _presorted);
    end;

    declare
        _shuffled text[] := array[
            '0.0.88'
            ,'1.0.0+stuff'
            ,'1.0.0'
            ,'1.0.0-a'
            ,'0.0.88+stuff'
            ,'0.0.88-alpha-2-a'
            ,'1.0.0-a.123'
        ];
    begin
        -- `min(semver)` and `max(semver)` are also possible:
        assert (select min(v::semver) from unnest(_shuffled) as v)::text = '0.0.88-alpha-2-a';
        assert (select max(v::semver) from unnest(_shuffled) as v)::text in ('1.0.0', '1.0.0+stuff');
    end;

    perform null::semver;

    -- There are some circumstances (like when parsing PGXN Version Ranges) where you may want to specify the
    -- operator dynamically rather that hardcode it in an expression; meet `semver_cmp(semver, semver, text)`:
    assert semver_cmp('0.4.1', '0.4.2', '<');
    assert semver_cmp('0.4.1', '0.4.2', '<=');
    assert semver_cmp('0.4.2', '0.4.2', '<=');
    assert semver_cmp('0.4.2', '0.4.2', '==');
    assert semver_cmp('0.4.2', '0.4.2', '=');
    assert semver_cmp('0.4.2', '0.4.2', '>=');
    assert semver_cmp('0.4.3', '0.4.2', '>=');
    assert semver_cmp('0.4.3', '0.4.2', '>');
    assert semver_cmp('0.4.3', '0.4.2', '<>');
    assert semver_cmp('0.4.2', '0.4.3', '<>');
    assert semver_cmp('0.4.3', '0.4.2', '!=');
    assert semver_cmp('0.4.2', '0.4.3', '!=');

    -- Speaking of PGXN `META.json` Version Ranges, you might want some help parsing them:
    assert (select array_agg(r.*) from meta_pgxn_version_range('1.9.8') r)
        = array[row('>='::text, '1.9.8'::text, false)];
    assert (select array_agg(r.*) from meta_pgxn_version_range('0') r)
        = array[row(null::text, null::text, true)];
    assert (select array_agg(r.*) from meta_pgxn_version_range('> 1.8.0, != 1.8.4-alpha, < 2.0.0') r)
        = array[
            row('>'::text,   '1.8.0'::text,       false)
            ,row('!='::text, '1.8.4-alpha'::text, false)
            ,row('<'::text,  '2.0.0'::text,       false)
        ];

    -- You can even check a PGXN `META.json` Version Ranges specification directly against a given version:
    assert meta_pgxn_version_range_cmp('6.7.200-alpha-2+build.3', '0');
    assert meta_pgxn_version_range_cmp('not-a-semver', '>= 1.0.0') is null;
    assert meta_pgxn_version_range_cmp('1.8.4', '> 1.8.0, != 1.8.4-alpha, < 2.0.0');
    assert not meta_pgxn_version_range_cmp('1.7.0', '> 1.8.0, != 1.8.4-alpha, < 2.0.0');
    assert not meta_pgxn_version_range_cmp('1.8.0', '> 1.8.0, != 1.8.4-alpha, < 2.0.0');
    assert not meta_pgxn_version_range_cmp('1.8.4-alpha', '> 1.8.0, != 1.8.4-alpha, < 2.0.0');
    assert not meta_pgxn_version_range_cmp('2.0.0', '> 1.8.0, != 1.8.4-alpha, < 2.0.0');

    raise transaction_rollback;
exception
    when transaction_rollback then
end;
$procedure$
```

### Types

The following extra types have been defined _besides_ the implicit composite types of the [tables](#tables) and [views](#views) in this extension.

#### Domain: `semver`

```sql
CREATE DOMAIN semver AS text
  CHECK ((VALUE ~ semver_regexp(false)));
```

#### Domain: `semver_prerelease`

```sql
CREATE DOMAIN semver_prerelease AS text
  CHECK ((VALUE ~ semver_prerelease_regexp()));
```

#### Composite type: `semver_parsed`

This composite type can be used to access the individual parts of a `semver`.

A semantic version can take 4 forms.  Depending on the form, the `prerelease` and/or `build` fields may be
`NLL`.  `major`, `minor` and `patch` can never be `NULL` for a valid semantic version.

| #  | Form                                           | Example           | `prerelease` | `build`    |
| -- | ---------------------------------------------- | ----------------- | ------------ | ---------- |
| 1. | `<major>.<minor>.<patch>`                      | 1.0.22            | `NULL`       | `NULL`     |
| 2. | `<major>.<minor>.<patch>-<prerelease>`         | 1.0.22-alpha2     | `NOT NULL`   | `NULL`     |
| 3. | `<major>.<minor>.<patch>-<prerelease>+<build>` | 1.0.22-alpha2+arm | `NOT NULL`   | `NOT NULL` |
| 4. | `<major>.<minor>.<patch>+<build>`              | 1.0.22+arm        | `NULL`       | `NOT NULL` |

To unparse/serialize a `semver_parsed` composite values, cast it to `semver` or `text`.

```sql
CREATE TYPE semver_parsed AS (
  major text,
  minor text,
  patch text,
  prerelease text,
  build text
);
```

## Authors and contributors

* [Rowan](https://www.bigsmoke.us/) originated this extension in 2022 while
  developing the PostgreSQL backend for the [FlashMQ SaaS MQTT cloud
  broker](https://www.flashmq.com/).  Rowan does not like to see himself as a
  tech person or a tech writer, but, much to his chagrin, [he
  _is_](https://blog.bigsmoke.us/category/technology). Some of his chagrin
  about his disdain for the IT industry he poured into a book: [_Why
  Programming Still Sucks_](https://www.whyprogrammingstillsucks.com/).  Much
  more than a “tech bro”, he identifies as a garden gnome, fairy and ork rolled
  into one, and his passion is really to [regreen and reenchant his
  environment](https://sapienshabitat.com/).  One of his proudest achievements
  is to be the third generation ecological gardener to grow the wild garden
  around his beautiful [family holiday home in the forest of Norg, Drenthe,
  the Netherlands](https://www.schuilplaats-norg.nl/) (available for rent!).

## Colophon

This `README.md` for the `pg_text_semver` extension was automatically generated using the [`pg_readme`](https://github.com/bigsmoke/pg_readme) PostgreSQL extension.