JSONObject crashes with Postgres 16 and server side bindings

[john-parton]

Tests fail with Postgres 16 and server side bindings

Steps to replicate

1. Pull down main
2. Up a postgres 16 database (supplied docker-compose.yml)
3. Use supplied settings file
4. Install requirements
5. Run ./runtests.py --settings test_postgres db_functions.comparison

docker-compose.yml

services:
    postgres:
        image: postgres:16.3
        shm_size: 1g
        ports:
        - "5436:5432"
        environment:
            POSTGRES_USER: user
            POSTGRES_PASSWORD: postgres
            POSTGRES_DB: django

test_postgres.py

from test_sqlite import *  # NOQA

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql",
        "USER": "user",
        "NAME": "django",
        "PASSWORD": "postgres",
        "HOST": "localhost",
        "PORT": 5436,
        "OPTIONS": {
            "server_side_binding": True,
        },
    },
}

Here's the output of my pip freeze for reference

aiohappyeyeballs==2.4.0
aiohttp==3.10.5
aiosignal==1.3.1
aiosmtpd==1.4.6
argon2-cffi==23.1.0
argon2-cffi-bindings==21.2.0
asgiref==3.8.1
atpublic==5.0
attrs==24.2.0
bcrypt==4.2.0
black==24.8.0
certifi==2024.8.30
cffi==1.17.1
charset-normalizer==3.3.2
click==8.1.7
-e git+ssh://git@github.com/django/django.git@aa5293068782dfa2d2173c75c8477f58a9989942#egg=Django
docutils==0.21.2
frozenlist==1.4.1
geoip2==4.8.0
h11==0.14.0
idna==3.8
Jinja2==3.1.4
MarkupSafe==2.1.5
maxminddb==2.6.2
multidict==6.0.5
mypy-extensions==1.0.0
numpy==2.1.1
outcome==1.3.0.post0
packaging==24.1
pathspec==0.12.1
pillow==10.4.0
platformdirs==4.2.2
psycopg==3.2.1
psycopg-binary==3.2.1
psycopg-pool==3.2.2
pycparser==2.22
pylibmc==1.6.3
pymemcache==4.0.0
PySocks==1.7.1
pywatchman==2.0.0
PyYAML==6.0.2
redis==5.0.8
requests==2.32.3
selenium==4.24.0
setuptools==74.1.2
sniffio==1.3.1
sortedcontainers==2.4.0
sqlparse==0.5.1
tblib==3.0.0
trio==0.26.2
trio-websocket==0.11.1
typing_extensions==4.12.2
tzdata==2024.1
urllib3==2.2.2
websocket-client==1.8.0
wsproto==1.2.0
yarl==1.9.11

Python 3.12.3

Made this discovery while trying to finish a JSON feature, comment here: ​https://github.com/django/django/pull/18541#issuecomment-2331630403

[john-parton]

I can confirm this is also an issue with 5.1.1 and 5.1, but not an issue with 5.0.9.

Here's where I think the error was introduced.

5.0.9: ​https://github.com/django/django/blob/8e68f938f376cf2ca22a7e8ff0bcbe1b7a5832d1/django/db/models/functions/comparison.py#L163-L176
5.1: ​https://github.com/django/django/blob/373cb3037fe4e67adbac9ac43340391e859aa957/django/db/models/functions/comparison.py#L192

Basically on postgres 16, there's an attempt to use "native" JSON, but it doesn't work for nested objects.

[Natalia Bidart]

Thank you John!

Confirmed this is a regression in 81ccf92f154c6d9eac3e30bac0aa67574d0ace15.

[john-parton]

Thanks. I assume Nick can take a crack at it? Otherwise I can take a look. A little busy at the moment, so not sure when I could get to it.

EDIT

Do we need to add Postgres 16/15 to CI? I know there's already a ton of different configs tested, but it would have caught this if it were in the CI pipeline.

[john-parton]

Pull request here: ​https://github.com/django/django/pull/18549

[Natalia Bidart]

Replying to john-parton:

Thanks. I assume Nick can take a crack at it? Otherwise I can take a look. A little busy at the moment, so not sure when I could get to it.

Thank you John for your PR and work on this. We'll review soon!

Do we need to add Postgres 16/15 to CI? I know there's already a ton of different configs tested, but it would have caught this if it were in the CI pipeline.

This is a very valid point and I would like us to pursue a more sustainable solution for this testing other than "each one does it on their own laptop".
John, would you be willing to raise this issue in the Django Forum to see if we could get some traction to setup this? I think we could have at least a new entry in the scheduled tests to test all supported version, or at least the oldest (current setup) and the newest.

[john-parton]

Topic here: ​https://forum.djangoproject.com/t/postgres-16-ci-postgres-16-in-use/34649

Yeah, I'm not sure what the cost in $$$ to run the CI is. I think this is a pretty unusual corner case, so maybe it's not worth the hassle.

[GitHub <noreply@…>]

In 92f860e3:

Refs #35734 -- Added entry to scheduled tests workflow to test newer PostgreSQL versions.

[Sarah Boyce]

​Here is an approach which uses the native JSONObject function for server side bindings, casting the keys to text. Adding it here for a record.

[john-parton]

Replying to Sarah Boyce:

​Here is an approach which uses the native JSONObject function for server side bindings, casting the keys to text. Adding it here for a record.

I can create a separate ticket for this. "Enhancement", something like "use native JSONObject on Postgres 16+ with server side bindings"?

I'm assuming that it's a "good thing" to prefer the native JSONObject over just using jsonb_build_object all the time. In my experience, there is no _practical_ difference, but I'm assuming the original change was accepted because when support for Postgres 14 and 15 is dropped, we can drop the jsonb_build_object code path with a simple delete. Does that sound right?

[john-parton]

I've created the separate ticket to track use of the native json object with postgres 16+ and server side bindings: https://code.djangoproject.com/ticket/35778#ticket

[Sarah Boyce <42296566+sarahboyce@…>]

In f22ff456:

Fixed #35734 -- Used JSONB_BUILD_OBJECT database function on PostgreSQL when using server-side bindings.

Regression in 81ccf92f154c6d9eac3e30bac0aa67574d0ace15.

[Sarah Boyce <42296566+sarahboyce@…>]

In 22bce642:

[5.1.x] Fixed #35734 -- Used JSONB_BUILD_OBJECT database function on PostgreSQL when using server-side bindings.

Regression in 81ccf92f154c6d9eac3e30bac0aa67574d0ace15.

Backport of f22ff4561ada77be98ca4db3ce117caca897696e from main.