Example:

    create_table :users do |t|
      t.string :name
      t.index 'lower(name) varchar_pattern_ops'
    end

Fixes #19090.
Fixes #21765.
Fixes #21819.
Fixes #24359.
Signed-off-by: NJeremy Daer <jeremydaer@gmail.com>

Originally, `{insert|update|delete}_sql` is protected methods.
We can use the `{insert|update|delete}` public methods instead.

Some tests does not work for unprepared statements.
Add `if ActiveRecord::Base.connection.prepared_statements` and fix a
regex for fix tests failure with `prepared_statements: false`.

Arel handles substitution for bind parameters by now.

The returning_disabled configuration option is required to make postgresql partitioning triggers work. This commit fixes a bug where an invalid query would be made in cases where returning_disabled was true and objects were created with no attributes defined.

The type map was introduced in aafee233, but wasn't properly filled.

This mainly adjusts many locations, that expected strings instead of
integers or boolean.

add_pg_decoders is moved after setup of the StatementPool, because
execute_and_clear could potentially make use of it.

Lowercase raw SQL has been replaced by 07b659ca already. This commit
replaces everything else of raw SQL.

`bound_attributes` is now used universally across the board, removing
the need for the conversion layer. These changes are mostly mechanical,
with the exception of the log subscriber. Additional, we had to
implement `hash` on the attribute objects, so they could be used as a
key for query caching.

When table has a composite primary key, the `primary_key` method for
sqlite3 and postgresql was only returning the first field of the key.

Ensures that it will return nil instead, as AR dont support composite pks.

Oh hey, we got to remove some code because of that!

Arel handles this for us automatically. Updated tests, as BindParam is
no longer a subclass of SqlLiteral. We should remove the second argument
to substitute_at entirely, as it's no longer used

This is a reacon to https://github.com/rails/rails/commit/d6c1205584b1ba597db4071b168681678b1e9875#commitcomment-7502487
This backwards incompatibility was introduced with d6c12055 to fix #7516.
However both `connection.default_sequence_name` and `model.sequence_name` are public API.
The PostgreSQL adapter should honor the interface and return strings.

/cc @matthewd @chancancode

Fixes #16623 introduced by https://github.com/rails/rails/commit/3d5a2019bcccc6fb01bee4811ca669f4383edb51

This test was inspired by #14866. That PR would break this
functionality and we should make sure we notice that in the future.

[Yves Senn & Matthew Draper]

[Yves Senn & Matthew Draper]

This setups the helper method which other tests can benefit from.

The pk_an_sequence_for query previously joined against pg_class's oid
for rows in pg_depend, but pg_depend's objid may point to other system
tables, such as pg_attrdef.  If a row in one of those other tables
coincidentally has the same oid as an (unrelated) sequence, that
sequence name may be returned instead of the real one.

This ensures that only the pg_depend entries pointing to pg_class are
considered.

remove created state after test execution, not before the next test.
This prevents the leak of the `ex` table outside of a single test.

Currently if you attempt to use a database that does not exist  you get an error:

```
PG::ConnectionBad FATAL:  database "db_error" does not exist
```

The solution is easy, create and migrate your database however new developers may not know these commands by memory. Instead of requiring the developer to search for a solution, tell them how to fix the problem in the error message:

```
ActiveRecord::NoDatabase: FATAL:  database "db_error" does not exist
Run `$ bin/rake db:create db:migrate` to create your database
```

Active Record should not know about `rake db:migrate` so this additional information needs to come from the railtie. Potential alternative implementation suggestions are welcome.

Previously, executing an insert SQL in PostgreSQL with a command like this:

    insert into articles(
      number)
    values(
      5152
    )

would not work because the adapter was unable to extract the correct articles table name.

Deprecate SchemaStatements#distinct, and make SchemaStatements#columns_for_distinct nodoc.
Conflicts:
	activerecord/CHANGELOG.md

The combination of a :uniq => true association and the #distinct call
in #construct_limited_ids_condition combine to create invalid SQL, because
we're explicitly selecting DISTINCT, and also sending #distinct on to AREL,
via the relation#distinct_value.

Rather than build a select distinct clause in #construct_limited_ids_condition,
I set #distinct! and pass just the columns into the select statement.
This requires introducing a #columns_for_distinct method to return the
select columns but not the statement itself.

Created a layer of abstraction for the valid type checking in schema dumper. Now, connection handles the check for valid types so that each database can handle the changes individually.

This reverts commit c321b309.

Conflicts:
	activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
	activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

Reason: failing test

  1) Error:
test_valid_column(ActiveRecord::ConnectionAdapters::SQLite3AdapterTest):
NoMethodError: undefined method `column' for
    test/cases/adapters/sqlite3/sqlite3_adapter_test.rb:29:in
`test_valid_column'