r/adbcdrivermanager: behavior of depth argument in adbc_connection_get_objects()

[nbenn]

Going by the docs I was expecting that passing depth = 4L I get back schema info up to columns.

library(adbcdrivermanager)
db <- adbc_database_init(adbcsqlite::adbcsqlite(), uri = ":memory:")
con <- adbc_connection_init(db)
write_adbc(datasets::swiss, con, "swiss")

res <- nanoarrow::convert_array_stream(
  adbc_connection_get_objects(con, 4L)
)

res[["catalog_db_schemas"]][[1L]][["db_schema_tables"]][[1L]]
#>   table_name table_type table_columns table_constraints
#> 1      swiss      table          NULL              NULL

If I use default depth of 0L, I get the expected info.

@paleolimbot Is 3L the largest "sensible" value? Maybe a warning for larger values would be helpful? Or maybe being a bit more clear about this in the docs? As things stand, it might be a bit misleading.

[paleolimbot]

I can't speak to this off the top of my head since the concept of a "catalog" is something that I have only recently run into. The first thing I would try is whether a value of 4L works in the Postgres driver (which has seen a little more use than the sqlite driver).

(I can also look into it in the next few days!)

[lidavidm]

/// \brief Return metadata on catalogs, schemas, tables, and columns.
///
/// \see AdbcConnectionGetObjects
#define ADBC_OBJECT_DEPTH_ALL 0
/// \brief Return metadata on catalogs only.
///
/// \see AdbcConnectionGetObjects
#define ADBC_OBJECT_DEPTH_CATALOGS 1
/// \brief Return metadata on catalogs and schemas.
///
/// \see AdbcConnectionGetObjects
#define ADBC_OBJECT_DEPTH_DB_SCHEMAS 2
/// \brief Return metadata on catalogs, schemas, and tables.
///
/// \see AdbcConnectionGetObjects
#define ADBC_OBJECT_DEPTH_TABLES 3
/// \brief Return metadata on catalogs, schemas, tables, and columns.
///
/// \see AdbcConnectionGetObjects
#define ADBC_OBJECT_DEPTH_COLUMNS ADBC_OBJECT_DEPTH_ALL

I suppose I did this backwards. So you want 0.

[paleolimbot]

@nbenn Are any changes to ADBC required to get the information you need here?