postgis backend doesn't respect custom index names.

[Thomas Steen Rasmussen]

Hello,

I am trying to create an index for a table with some geodjango fields. The PostGIS code doesn't take the index name into account, it always generates one based on table and field name.
Compare ​https://github.com/django/django/blob/master/django/contrib/gis/db/backends/postgis/schema.py#L38 with ​https://github.com/django/django/blob/master/django/db/backends/base/schema.py#L967 and it is clear that some logic to determine the name is missing. That leads to the following result in sqlmigrate:

    --
    -- Create index dar_navngivenvej_historik_vvnl on field(s) vejnavnebeliggenhed_vejnavnelinje of model darnavngivenvejhistorik
    --
    CREATE INDEX "dawarepl_dar_navngivenvej_historik_vejnavnebeliggenhed_vejnavnelinje_id" ON "dawarepl_dar_navngivenvej_historik"USING GIST ("vejnavnebeliggenhed_vejnavnelinje");
    --
    -- Create index dar_navngivenvej_historik_vvno on field(s) vejnavnebeliggenhed_vejnavneområde of model darnavngivenvejhistorik
    --
    CREATE INDEX "dawarepl_dar_navngivenvej_historik_vejnavnebeliggenhed_vejnavneområde_id" ON "dawarepl_dar_navngivenvej_historik"USING GIST ("vejnavnebeliggenhed_vejnavneområde");
    --
    -- Create index dar_navngivenvej_historik_vvtp on field(s) vejnavnebeliggenhed_vejtilslutningspunkter of model darnavngivenvejhistorik
    --
    CREATE INDEX "dawarepl_dar_navngivenvej_historik_vejnavnebeliggenhed_vejtilslutningspunkter_id" ON "dawarepl_dar_navngivenvej_historik"USING GIST ("vejnavnebeliggenhed_vejtilslutningspunkter");
    --

In case it isn't clear, the index names in the SQL comment are "mine" from the Meta: section of the model, but the index names used in the actual SQL are the much longer autogenerated ones.

I believe this should be fixed with a construct like ​https://github.com/django/django/blob/master/django/db/backends/base/schema.py#L967 so autogenerated names are only used when 'name' not in kwargs.

[Mariusz Felisiak]

Thanks for the report. Agreed, we should respect Index.name for spatial indexes.

[Claude Paroz]

Tentatively set easy picking (without thorough examination).

[Ahisahar Pretel]

I think I can take a look at this if no one started working already on this.

[Pratik Kumar]

This ticket seems inactive. So I am assigning it to myself

[Pratik Kumar]

​https://github.com/Pratik1999/django-1/tree/ticket_30846

These are the changes I have made, shall I submit the pull request? Or more changes are needed?

[Mariusz Felisiak]

Pratik1999, PR is the proper place to discuss patches. At first glance, tests are missing.

[Pratik Kumar]

pull request :
​https://github.com/django/django/pull/12440

[Mariusz Felisiak <felisiak.mariusz@…>]

In 20ba3ce4:

Fixed #30846 -- Made PostGIS backend respect Index's name argument.