How to insert nested/composite types into DuckDB from a DataFrame?

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Looks like it’s not supported at the moment (same issue for the Rust client: Appender support for arrays (or alternative) · Issue #422 · duckdb/duckdb-rs · GitHub).

As a workaround, you can:

# flatten the df
tab1_df = DataFrame(id=1:10, vals=fill([1,2,3],10))
flat_df = flatten(tab1_df, [:vals])

# register the data frame or create the table in whatever way
DuckDB.register_data_frame(db_mem, flat_df, "flat_tab1")

# create aggregated table 
DuckDB.query(
  db_mem,
  "CREATE OR REPLACE TABLE tab1 AS
  SELECT
    id,
    ARRAY_AGG(vals) AS vals,
  FROM flat_tab1
  GROUP BY
    id",
)

# trust buy verify
DuckDB.query(db_mem, "FROM tab1") |> DataFrame

Please let me know if this is helpful.

PS. If you can add the errors you’re having, it will help more people find this issue (especially in the future)

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