sql: show all indexes on a database

[awoods187]

Describe the problem
We have a show index from table command but it'd be useful to see all of the indexes on a database with a show index from database or something similar. It could work something like this underneath the hood from MySQL:

SELECT
    DISTINCT TABLE_NAME,
    INDEX_NAME
FROM
    INFORMATION_SCHEMA.STATISTICS
WHERE
    TABLE_SCHEMA = `schema_name`;

And presents something like this:

  table_name | index_name | non_unique | seq_in_index | column_name | direction | storing | implicit
+------------+------------+------------+--------------+-------------+-----------+---------+----------+
  order      | primary    |   false    |            1 | o_w_id      | ASC       |  false  |  false
  order      | primary    |   false    |            2 | o_d_id      | ASC       |  false  |  false
  order      | primary    |   false    |            3 | o_id        | DESC      |  false  |  false
  warehouse  | primary    |   false    |            1 | w_id        | ASC       |  false  |  false
 history    | primary    |   false    |            1 | rowid       | ASC       |  false  |  false

[rohany]

what kind of syntax would you be looking for in this command? It is unclear how to support in the parser both show indexes from <tablename> and show indexes from <databasename> due to conflicts. I was considering the syntax show indexes from database <databasename>, if this sounds good to you.

[rohany]

Implement in #37942. You can use the command show indexes from database <database_name> to see this information now.