system.tables does not show partition_key/sorting_key for Iceberg table before first read/insert

[alsugiliazova]

For an Iceberg table with defined partition and sort order, system.tables initially returns empty partition_key and sorting_key. After the first query against the table (even if the table is empty), the sorting key appears. The partition_key only appears after first insert.

That is inconsistent.

This seems related to lazy loading of Iceberg metadata.

SELECT partition_key
FROM system.tables
WHERE name = 'name_eb73f7dc_174e_11f1_bd5d_de7b9eea348f'

Query id: 29e2b3f0-9752-4251-9c2b-53b3654fa544

   ┌─partition_key─┐
1. │               │
   └───────────────┘

1 row in set. Elapsed: 0.008 sec. 

SELECT sorting_key
FROM system.tables
WHERE name = 'name_eb73f7dc_174e_11f1_bd5d_de7b9eea348f'

Query id: 56cfe01f-fed0-4f4d-8968-768e4d41a7b4

   ┌─sorting_key─┐
1. │             │
   └─────────────┘

1 row in set. Elapsed: 0.002 sec. 

SELECT count()
FROM name_eb73f7dc_174e_11f1_bd5d_de7b9eea348f

Query id: be55a919-1f1e-40e1-90a8-75e3bcacebed

   ┌─count()─┐
1. │       0 │
   └─────────┘

1 row in set. Elapsed: 0.004 sec. 

SELECT sorting_key
FROM system.tables
WHERE name = 'name_eb73f7dc_174e_11f1_bd5d_de7b9eea348f'

Query id: d723b4e0-9655-475d-aa5e-9439143274f4

   ┌─sorting_key─┐
1. │ name        │
   └─────────────┘

1 row in set. Elapsed: 0.002 sec. 

SELECT partition_key
FROM system.tables
WHERE name = 'name_eb73f7dc_174e_11f1_bd5d_de7b9eea348f'

Query id: be5075b0-0088-4a0f-b14b-af490d157634

   ┌─partition_key─┐
1. │               │
   └───────────────┘

[alsugiliazova]

And also before first insert sorting key is shown as
name

After insert:
name asc