Currently the environment file is not loaded in `dbconsole` command.
Therefore, for example, if use encrypted secrets values in database.yml,
`read_encrypted_secrets` will not be true, so the value can not be
used correctly.

Fixes #29717

Don't allow uuids with orphan curly braces

Skip query cache for in_batches and friends

Don't translate non-database exceptions.

Fix bug with long stream identifiers when using Postgres adapter

Improve the performance of writing attributes

Add `rails secrets:show` command

Do not update `secrets.yml.enc` when secretes do not change

Use `information_schema` to extract `generation_expression` for MariaDB

Fix default `CURRENT_TIMESTAMP` in schema dumping for MariaDB 10.2

Clarify i18n guide for how pluralization rules work by default

It's possible for developers toadd a custom driver and then call it
using `driven_by`. Because we were only skipping `register` for
`:rack_test` that meant any custom driver would attempt to be registered
as well.

The three listed here are special because Rails registers them with
special options. If you're registering your own custom driver then you
don't want to separately register that driver.

Fixes #29688

Update default app files in app_generator_test

The guide misleadingly indicates that the I18n gem will apply the CLDR pluralization rules for each language. This is not the case; only the English algorithm, with support for :zero, :one, and :other, is available by default. Locale-specific pluralization rules require additional configuration and must be supplied by the application (or by another gem).

The uuid validation regex was allowing uuids to have a single leading
curly brace or single trailing curly brace. Saving with such a uuid
would cause Postgres to generate an exception even though the record
seemed valid. With this change, the regex requires both a leading *and*
a trailing curly brace or neither to be valid.

Add ActiveModel::Errors#merge!

ActiveModel::Errors#merge! allows ActiveModel::Errors to append errors from
a separate ActiveModel::Errors instance onto their own.

Example:

    person = Person.new
    person.errors.add(:name, :blank)

    errors = ActiveModel::Errors.new(Person.new)
    errors.add(:name, :invalid)

    person.errors.merge!(errors)
    puts person.errors.messages
    # => { name: ["can't be blank", "is invalid"] }

Currently, if open a file with `secrets:edit` command, `secrets.yml.enc`
will be changed even if its contents do not change.

Therefore, even if only want to check secrets, the difference will come
out. This is a little inconvenient.

As a fix to the above problem, when content does not change,
`secrets.yml.ecn` is fixed so that it is not changed.

Since MariaDB 10.2, `CURRENT_TIMESTAMP` is shown as a function
(`current_timestamp()`). Fix matching column default to address that
case.

Fixes #29698.

Since MariaDB 10.2.5, `information_schema` supports Virtual Columns.

Fixes #29670.

This name more accurately describes what the method does, and also
disambiguates it from `_write_attribute`, which ignores aliases.

We can also make the method private, since it's not public API and only
called from one place - `update_columns` - without an explicit receiver.

Fix extracting MariaDB version

When secrets confirmed with the `secrets:edit` command, `secrets.yml.enc`
will change without updating the secrets.

Therefore, even if only want to check secrets, the difference will come
out. This is a little inconvenient.

In order to solve this problem, added the `secrets:show` command.
If just want to check secrets, no difference will occur use this command.

Currently `version` method always returns `5.5.5` because the
`full_version` is `5.5.5-10.x.y-MariaDB...` since MariaDB 10.x.
It should be ignored if the prefix is `5.5.5-`.

Whoops.

The `find_each`, `find_in_batches` and `in_batches` APIs usually operate
on large numbers of records, where it's preferable not to load them all
into memory at once.

If the query cache is enabled, it will hold onto the query results until
the end of the execution context (request/job), which means the memory
used is still proportional to the total number of records. These queries
are typically not repeated, so the query cache isn't desirable here.

The AbstractAdapter will translate all StandardErrors generated during the course of a query into ActiveRecord::StatementInvalids. Unfortunately, it'll also mangle non-database-related errors generated in ActiveSupport::Notification callbacks after the query has successfully completed. This should prevent it from translating errors from ActiveSupport::Notifications.

Allow mounting same engine under several locations

Fix `ActiveModel::Type::DateTime#serialize`

Mention Time.zone.parse possibly throwing ArgumentError

`ActiveModel::Type::DateTime#serialize` should return a `Time` object
so that finding by a datetime column works correctly.