Implement nested identifier access ( "Nested identifiers not yet supported" ) #11445

> create or replace view foo as select  {'field1': { 'subfield1': 'foo', subfield2: 'bar', subfield3: [10,20,30,40]}} as "the_column";
0 row(s) fetched.
Elapsed 0.001 seconds.

> select * from foo;
+-------------------------------------------------------------------------+
| the_column                                                              |
+-------------------------------------------------------------------------+
| {field1: {subfield1: foo, subfield2: bar, subfield3: [10, 20, 30, 40]}} |
+-------------------------------------------------------------------------+
1 row(s) fetched.
Elapsed 0.002 seconds.

> select the_column.field1.subfield3[2] from foo;
Internal error: Nested identifiers not yet supported for column foo.the_column.
This was likely caused by a bug in DataFusion's code and we would welcome that you file an bug report in our issue tracker

> create or replace view foo as select { 'subfield1': 'foo', subfield2: 'bar', subfield3: [10,20,30,40]} as "field1" ;
0 row(s) fetched.
Elapsed 0.008 seconds.

> select * from foo;
+---------------------------------------------------------------+
| field1                                                        |
+---------------------------------------------------------------+
| {subfield1: foo, subfield2: bar, subfield3: [10, 20, 30, 40]} |
+---------------------------------------------------------------+
1 row(s) fetched.
Elapsed 0.003 seconds.

> select field1.subfield3[2] from foo;
+----------------------------------------------------+
| get_field(foo.field1, Utf8("subfield3"))[Int64(2)] |
+----------------------------------------------------+
| 20                                                 |
+----------------------------------------------------+
1 row(s) fetched.
Elapsed 0.002 seconds.