ENH Add index for default_sort on many_many tables

[GuySartorelli]

default_sort on a DataObject results in an index being added. The same should happen with the join table for many_many relations.

Note that because MySQL (and probably others) can only use a single index at a time, I've opted to add the sort index columns into the existing child and parent ID indexes. This means we can filter by ID and sort by the default sort all using the same index.

If a different sort is applied, the first column (the parent or child ID) in the index can still be used for filtering.

Issue

• Check for missing or unnecessary indexes .github#414

[GuySartorelli]

Logic for this method is just all pulled out of buildSortDatabaseIndexes() so we can reuse it in DataObject for many_many join tables

[GuySartorelli]

I've referenced this in #11786

[emteknetnz]

Could you also rebase framework on to this? I attempted to do a kitchen sink CI run (just this PR, not any of the others) to double check this, though it complained that "Class Generated does not exist" - since there is no Generated class, instead DBGenerated, something's go wrong. I also go the same issue trying to run this PR locally.

[GuySartorelli]

I attempted to do a kitchen sink CI run (just this PR, not any of the others) to double check this, though it complained that "Class Generated does not exist" - since there is no Generated class, instead DBGenerated, something's go wrong

Generated is the injector service used for the $db spec. But since the injector config isn't set (because, as you noted, I need to rebase), it just thinks it's a class name.
Rebasing will resolve that, so will do.

[emteknetnz]

I'm just having a little trouble validating this works, though it's probably more my lack on understanding rather than any thing in this PR

Seems like the DB indexes are the same whether or not this PR is present or not?

// app/MyDataObject.php
use SilverStripe\ORM\DataObject;

class MyDataObject extends DataObject
{
    private static $table_name = 'MyDataObject';

    private static $db = [
        'Foo' => 'Varchar'
    ];

    private static $many_many = [
        'MyOtherDataObjects' => MyOtherDataObject::class
    ];

    private static $default_sort = 'Foo ASC';
}

// app/MyOtherDataObject.php
use SilverStripe\ORM\DataObject;

class MyDataObject extends DataObject
{
    private static $table_name = 'MyDataObject';

    private static $db = [
        'Bar' => 'Varchar'
    ];

    private static $many_many = [
        'MyOtherDataObjects' => MyOtherDataObject::class
    ];

    private static $default_sort = 'Title ASC';
}

```text
# show indexes from MyDataObject;
+--------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| Table        | Non_unique | Key_name  | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Ignored |
+--------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| MyDataObject |          0 | PRIMARY   |            1 | ID          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | NO      |
| MyDataObject |          1 | Foo       |            1 | Foo         | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | NO      |
| MyDataObject |          1 | ClassName |            1 | ClassName   | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | NO      |
+--------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+

# show indexes from MyOtherDataObject;
+-------------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| Table             | Non_unique | Key_name  | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Ignored |
+-------------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| MyOtherDataObject |          0 | PRIMARY   |            1 | ID          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | NO      |
| MyOtherDataObject |          1 | Bar       |            1 | Bar         | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | NO      |
| MyOtherDataObject |          1 | ClassName |            1 | ClassName   | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | NO      |
+-------------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+

# show indexes from MyDataObject_MyOtherDataObjects;

+---------------------------------+------------+---------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| Table                           | Non_unique | Key_name            | Seq_in_index | Column_name         | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Ignored |
+---------------------------------+------------+---------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| MyDataObject_MyOtherDataObjects |          0 | PRIMARY             |            1 | ID                  | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | NO      |
| MyDataObject_MyOtherDataObjects |          1 | MyDataObjectID      |            1 | MyDataObjectID      | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | NO      |
| MyDataObject_MyOtherDataObjects |          1 | MyOtherDataObjectID |            1 | MyOtherDataObjectID | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | NO      |
+---------------------------------+------------+---------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+

[GuySartorelli]

It's not the default sort for either model, it's for the many_many join table itself. It's documented in https://docs.silverstripe.org/en/6/developer_guides/model/relations/#:~:text=To%20ensure%20this,to%20your%20config

You need to add some YAML config (the extrafields can be in your PHP class but the sort has to be in YAML)

MyDataObject:
  many_many_extraFields:
    MyOtherDataObjects:
        SomeField: 'Int'

MyDataObject_MyOtherDataObjects:
  default_sort: 'SomeField ASC'

[GuySartorelli]

Can you please also merge the other PRs which have been approved? None of them except the docs PR rely on this in any way.

[emteknetnz]

Cool thanks, index now shows up with this PR