Schema dumping in the Rails 6.0.0 Release is Broken Given a Table With Multiple Unique Constraints

[BenMcH]

Issue

The following commit changed how columns were fetched for a table: 92ff32a

The new functionality duplicates columns in my schema.rb file once per unique key constraint, resulting in my schema.rb file being unable to properly stand up a new database due to duplicate column definitions.

When I manually run the old SQL from before the aforementioned commit against my development database, the tables that meet the following criteria only get one entry per column. After the patch, the new SQL returns N number of columns depending on the number of unique indexes on the table.

Expected behavior

Each column definition should only be output to schema.rb once

Actual behavior

Column names are duplicated in schema.rb

How to reproduce

1. Create a DB table with the following SQL

CREATE TABLE dbo.examples (
	id int IDENTITY(1,1) NOT NULL,
	example int DEFAULT 0 NOT NULL,
	CONSTRAINT IX_EXAMPLE UNIQUE (example),
	CONSTRAINT PK_EXAMPLE PRIMARY KEY (id)
);

2. Run rails db:schema:dump
3. Your schema.rb file should now contain the following code:

  create_table "examples", id: :integer, force: :cascade do |t|
    t.integer "example", default: 0, null: false
    t.integer "example", default: 0, null: false
    t.index ["example"], name: "IX_EXAMPLE", unique: true
  end

Details

• Rails version: 6.0.3.4

• SQL Server adapter version: 6.0.0

• TinyTDS version: 2.1.3

• FreeTDS details:

  Compile-time settings (established with the "configure" script)
                            Version: freetds v1.1.24
             freetds.conf directory: /usr/local/etc
     MS db-lib source compatibility: no
        Sybase binary compatibility: no
                      Thread safety: yes
                      iconv library: yes
                        TDS version: 7.3
                              iODBC: no
                           unixodbc: yes
              SSPI "trusted" logins: no
                           Kerberos: no
                            OpenSSL: yes
                             GnuTLS: no
                               MARS: yes
  

[wpolicarpo]

Hey, thanks for the report. I'm AFK this week with limited access to internet, but will try to see if I can come up with a fix for this.

[BenMcH]

Thank you for the quick response. If I get some time this week, I may poke at it as well and submit a PR if I find a fix.

[BenMcH]

@wpolicarpo do you think that we could get this merged this week? I'd like to finish our rails 6 migration in the next week or so.