[Django] #31300: Add Generated Columns (PostgreSQL) support

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Feb 22, 2020, 6:34:16 AM2/22/20

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#31300: Add Generated Columns (PostgreSQL) support
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
Dulmandakh |
Type: New | Status: new
feature |
Component: Database | Version: master
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
PostgreSQL 12 added support for Generated Columns, see
https://www.postgresql.org/docs/12/ddl-generated-columns.html. And I find
it very interesting and useful, for example with SearchVectorField.

I imagine it would be called GeneratedField and accept base_field as
ArrayField, then expression to generate a value for the field. For
example,

{{{
class Album(models.Model):
...
title = models.CharField(max_length=120)
search = GeneratedField(
SearchVectorField(),
F('title')
)
}}}

then generate SQL something like below.

{{{
CREATE TABLE album (
...
title char(120),
search tsvector GENERATED ALWAYS AS title STORED
);
}}}

I would like to work on this feature, but don't know how to pass
expression and generate migration using the expression.

--
Ticket URL: <https://code.djangoproject.com/ticket/31300>
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Feb 25, 2020, 2:37:12 AM2/25/20

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Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by felixxm):

* status: new => closed
* resolution: => wontfix

Comment:

We have an accepted ticket #30511 about identity columns on PostgreSQL,
and I think we should stay with this. Generated/Function-based virtual
columns are a huge topic that would require many changes and have many
caveats, e.g. functions must be deterministic. They are feasible also on
Oracle. This kind of features require few weeks (even months) of works, a
precise plan, and should be preceded by a discussion on
DevelopersMailingList and even DEP.

--
Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:1>

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Apr 24, 2021, 2:47:40 AM4/24/21

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#31300: Add function-based virtual fields on PostgreSQL and Oracle.
-------------------------------------+-------------------------------------
Reporter: Dulmandakh | Owner: nobody
Type: New feature | Status: closed

Component: Database layer | Version: dev

(models, ORM) |
Severity: Normal | Resolution: wontfix
Keywords: | Triage Stage:
| Unreviewed

Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Petr Přikryl):

* cc: Petr Přikryl (added)

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:2>

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Jan 2, 2023, 1:57:38 AM1/2/23

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#31300: Add function-based virtual fields.

-------------------------------------+-------------------------------------
Reporter: Dulmandakh | Owner: nobody

Type: New feature | Status: new

Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution:

Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* status: closed => new
* resolution: wontfix =>
* stage: Unreviewed => Accepted

Comment:

Tentatively accepted, based on the [https://groups.google.com/g/django-
developers/c/9Mf7YqDA4bg/m/wb07E71oAAAJ feedback] from the mailing list.

--
Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:3>

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Jan 2, 2023, 1:58:33 AM1/2/23

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#31300: Add function-based virtual fields.
-------------------------------------+-------------------------------------

Reporter: Dulmandakh | Owner: Jeremy
| Nauta
Type: New feature | Status: assigned

Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* owner: nobody => Jeremy Nauta
* needs_better_patch: 0 => 1
* has_patch: 0 => 1
* status: new => assigned

Comment:

[https://github.com/django/django/pull/16417 PR]

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:4>

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Jan 11, 2023, 4:10:58 AM1/11/23

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Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by elonzh):

* cc: elonzh (added)

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:5>

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Mar 27, 2023, 6:28:50 AM3/27/23

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Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Paolo Melchiorre):

* needs_better_patch: 1 => 0

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:6>

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Mar 27, 2023, 7:42:53 AM3/27/23

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Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* needs_better_patch: 0 => 1

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:7>

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Apr 7, 2023, 2:31:28 PM4/7/23

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Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Jeremy Nauta):

* needs_better_patch: 1 => 0

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:8>

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Jun 20, 2023, 4:08:31 AM6/20/23

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Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Lily Foote):

* cc: Lily Foote (added)

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:9>

Django

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Jul 3, 2023, 4:44:04 AM7/3/23

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Keywords: field, database, | Triage Stage: Accepted
generated |
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Paolo Melchiorre):

* cc: Paolo Melchiorre (added)
* keywords: => field, database, generated

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:10>

Django

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Jul 21, 2023, 9:05:53 PM7/21/23

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Keywords: field, database, | Triage Stage: Ready for
generated | checkin
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Jeremy Nauta):

* stage: Accepted => Ready for checkin

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:11>

Django

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Jul 22, 2023, 1:54:30 PM7/22/23

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Keywords: field, database, | Triage Stage: Accepted
generated |

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* stage: Ready for checkin => Accepted

Comment:

Jeremy, you cannot mark your own patches as RFC, check out
[https://docs.djangoproject.com/en/4.2/internals/contributing/triaging-
tickets/#ready-for-checkin docs].

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:12>

Django

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Jul 27, 2023, 5:25:05 AM7/27/23

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Keywords: field, database, | Triage Stage: Ready for
generated | checkin

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Paolo Melchiorre):

* stage: Accepted => Ready for checkin

Comment:

Mariusz if I have interpreted the documentation correctly, having just
reviewed it again and not being the author of the PR, I have marked it as
an RFC.

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:13>

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Jul 27, 2023, 5:29:10 AM7/27/23

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Has patch: 1 | Needs documentation: 0

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Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Lily Foote):

One thing that might help this land is review of the Oracle support I
added in https://github.com/django/django/pull/16860. There's a few open
questions that could use thought from more people.

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:14>

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Jul 27, 2023, 5:46:00 AM7/27/23

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Has patch: 1 | Needs documentation: 0

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Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Paolo Melchiorre):

I personally can't help with Oracle testing, as I believe many others
here, but if there weren't other people able to help, as Adam has already
suggested [1] in the PR comments, I wouldn't block the merge of this
feature because it lacks the Oracle support given how little it is used.

[1] https://github.com/django/django/pull/16417#issuecomment-1508222534

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:15>

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-------------------------------------+-------------------------------------

Changes (by jul...@pinabausch.org):

* cc: jul...@pinabausch.org (added)

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:16>

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Sep 4, 2023, 3:31:46 AM9/4/23

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Keywords: field, database, | Triage Stage: Accepted
generated |

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* needs_better_patch: 0 => 1

* stage: Ready for checkin => Accepted

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:17>

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Sep 7, 2023, 12:21:23 AM9/7/23

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Keywords: field, database, | Triage Stage: Ready for
generated | checkin

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* needs_better_patch: 1 => 0

* stage: Accepted => Ready for checkin

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:18>

Django

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Sep 7, 2023, 4:07:30 AM9/7/23

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#31300: Add function-based virtual fields.
-------------------------------------+-------------------------------------
Reporter: Dulmandakh | Owner: Jeremy
| Nauta

Type: New feature | Status: closed

Component: Database layer | Version: dev
(models, ORM) |

Severity: Normal | Resolution: fixed

Keywords: field, database, | Triage Stage: Ready for
generated | checkin

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak <felisiak.mariusz@…>):

* status: assigned => closed
* resolution: => fixed

Comment:

In [changeset:"f333e3513e8bdf5ffeb6eeb63021c230082e6f95" f333e35]:
{{{
#!CommitTicketReference repository=""
revision="f333e3513e8bdf5ffeb6eeb63021c230082e6f95"
Fixed #31300 -- Added GeneratedField model field.

Thanks Adam Johnson and Paolo Melchiorre for reviews.

Co-Authored-By: Lily Foote <co...@lilyf.org>
Co-Authored-By: Mariusz Felisiak <felisiak...@gmail.com>
}}}

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:19>

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Sep 20, 2023, 3:00:50 AM9/20/23

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Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by GitHub <noreply@…>):

In [changeset:"0b506bfe1ab9f1c38e439c77b3c3f81c8ac663ea" 0b506bf]:
{{{
#!CommitTicketReference repository=""
revision="0b506bfe1ab9f1c38e439c77b3c3f81c8ac663ea"
Refs #31300 -- Added example to GeneratedField release notes.
}}}

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:20>

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Sep 20, 2023, 3:02:09 AM9/20/23

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Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Mariusz Felisiak <felisiak.mariusz@…>):

In [changeset:"7e4c1e8b3dd5806a17a617792a4fa0b763ef120d" 7e4c1e8]:
{{{
#!CommitTicketReference repository=""
revision="7e4c1e8b3dd5806a17a617792a4fa0b763ef120d"
[5.0.x] Refs #31300 -- Added example to GeneratedField release notes.

Backport of 0b506bfe1ab9f1c38e439c77b3c3f81c8ac663ea from main
}}}

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:21>

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Nov 2, 2023, 10:48:23 AM11/2/23

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Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Mariusz Felisiak <felisiak.mariusz@…>):

In [changeset:"208870b6122c4cbc39c3b2432e13db54c920db51" 208870b]:
{{{
#!CommitTicketReference repository=""
revision="208870b6122c4cbc39c3b2432e13db54c920db51"
Refs #31300 -- Allowed testing GeneratedField without collation.

CockroachDB and Snowflake don't support it.
}}}

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Ticket URL: <https://code.djangoproject.com/ticket/31300#comment:22>

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Nov 2, 2023, 10:49:11 AM11/2/23

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Has patch: 1 | Needs documentation: 0

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Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Mariusz Felisiak <felisiak.mariusz@…>):

In [changeset:"b735b90f439a964bda20a3ded19a39c5f0ce9b9a" b735b90]:
{{{
#!CommitTicketReference repository=""
revision="b735b90f439a964bda20a3ded19a39c5f0ce9b9a"
[5.0.x] Refs #31300 -- Allowed testing GeneratedField without collation.