postgresql_ext - Added idempotence always both in standard and in check mode

[RealGreenDragon]

SUMMARY

I figured out that my PR #504 add idempotence when version=latest in standard mode but NOT in check mode.

It is caused by missing update path check when version=latest but actually the check is possibile.

When latest extension version is requested (both in create and update), the default_version specified in extension control file is installed:

test=# SELECT name, default_version, installed_version FROM pg_catalog.pg_available_extensions WHERE name = 'adminpack';
   name    | default_version | installed_version
-----------+-----------------+-------------------
 adminpack | 2.1             |
(1 row)

test=# CREATE EXTENSION adminpack;
CREATE EXTENSION

test=# SELECT name, default_version, installed_version FROM pg_catalog.pg_available_extensions WHERE name = 'adminpack';
   name    | default_version | installed_version
-----------+-----------------+-------------------
 adminpack | 2.1             | 2.1
(1 row)

test=# DROP EXTENSION adminpack;
DROP EXTENSION

test=# SELECT name, default_version, installed_version FROM pg_catalog.pg_available_extensions WHERE name = 'adminpack';
   name    | default_version | installed_version
-----------+-----------------+-------------------
 adminpack | 2.1             |
(1 row)

test=# CREATE EXTENSION adminpack VERSION '1.0';
CREATE EXTENSION

test=# SELECT name, default_version, installed_version FROM pg_catalog.pg_available_extensions WHERE name = 'adminpack';
   name    | default_version | installed_version
-----------+-----------------+-------------------
 adminpack | 2.1             | 1.0
(1 row)

test=# ALTER EXTENSION adminpack UPDATE;
ALTER EXTENSION

test=# SELECT name, default_version, installed_version FROM pg_catalog.pg_available_extensions WHERE name = 'adminpack';
   name    | default_version | installed_version
-----------+-----------------+-------------------
 adminpack | 2.1             | 2.1
(1 row)

test=# ALTER EXTENSION adminpack UPDATE;
NOTICE:  version "2.1" of extension "adminpack" is already installed
ALTER EXTENSION

test=# SELECT name, default_version, installed_version FROM pg_catalog.pg_available_extensions WHERE name = 'adminpack';
   name    | default_version | installed_version
-----------+-----------------+-------------------
 adminpack | 2.1             | 2.1
(1 row)

It is confirmed also by the source code:

https://github.com/postgres/postgres/blob/d088ba5a5aa410d39b64f013e8433ad9eb3d17f1/src/backend/commands/extension.c#L3056_L3069

My PR add idempotence when provided version=latest also in check mode, parsing the extension default_version and using it to perform all checks (become useless as has been removed).

Other addictions:

• prev_version and version at module output (possible as default_version is now parsed)
• queries in output also in check mode
• error messages in module when it is sure that PostgreSQL command will fail
• all necessary tests

Bugfixes:

• module documentation -> queries return value had wrong value in name parameters
• useless checks in ext_delete function removed
• fixed ext_create function comment (an argument comment was missing)
• changelog fragment of my PR postgresql_ext - Added idempotence when version=latest #504 reported the wrong module name

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

postgresql_ext

ADDITIONAL INFORMATION

The second task of following play results not changed:

- hosts: dbs
  tasks:
    - name: Install extension adminpack at latest version
      community.postgresql.postgresql_ext:
        database: test
        state: present
        name: adminpack
        version: latest

    - name: Update extension adminpack at latest version in check_mode
      community.postgresql.postgresql_ext:
        database: test
        state: present
        name: adminpack
        version: latest
      check_mode: true

[RealGreenDragon]

Ready for review

[RealGreenDragon]

@Andersson007 I added new module return values and I put collection version 3.1.0 in documentation. Free to change it if this PR is planned for a different release.

[Andersson007]

@RealGreenDragon great job is here, thanks!

I took a quick look and left a comment.
I need to schedule a time slot for review. I hope i'll find time in the first half of the week.

Thanks!

[hunleyd]

pinging @keithf4 for his thoughts on the same

[hunleyd]

since #504 wasn't backported, i assume this shouldn't be either, @Andersson007 ?