Cannot write MAP type to DB

[DavZim]

I cannot write a MAP type to a duckdb using DBI::dbAppendTable().

con <- DBI::dbConnect(duckdb::duckdb())

DBI::dbExecute(con, "CREATE TABLE tbl (mp MAP(VARCHAR, VARCHAR));")
#> [1] 0
DBI::dbExecute(con, "INSERT INTO tbl VALUES (MAP {'a': 'b'})")
#> [1] 1

DBI::dbGetQuery(con, "DESCRIBE tbl")
#>   column_name           column_type null  key default extra
#> 1          mp MAP(VARCHAR, VARCHAR)  YES <NA>    <NA>  <NA>


DBI::dbReadTable(con, "tbl") |> str()
#> 'data.frame':	1 obs. of  1 variable:
#> $ mp:List of 1
#>  ..$ :'data.frame':	1 obs. of  2 variables:
#>  .. ..$ key  : chr "a"
#>  .. ..$ value: chr "b"

df <- data.frame(
  mp = I(list(data.frame(key = "page", value = "1")))
)
str(df) # same structure as the returned tbl data
#> 'data.frame':	1 obs. of  1 variable:
#>  $ mp:List of 1
#>   ..$ :'data.frame':	1 obs. of  2 variables:
#>   .. ..$ key  : chr "page"
#>   .. ..$ value: chr "1"
#>   ..- attr(*, "class")= chr "AsIs"

DBI::dbAppendTable(con, "tbl", df)
#> Error: rapi_execute: Failed to run query
#> Error: Conversion Error: Unimplemented type for cast (STRUCT("key" VARCHAR, "value" VARCHAR)[] -> MAP(VARCHAR, VARCHAR))

I am using

sapply(c("DBI", "duckdb"), packageVersion)
#> $DBI
#> [1] 1 2 3
#> 
#> $duckdb
#> [1] 1 0 0 1

(1.0.0-2 is being installed at the moment but I didnt see anything related to MAPs in the changelog from 1.0.0-1).
Update, I updated to 1.0.0-2 and I see the same error.

This is closely related to #165 and #61

[krlmlr]

Thanks, confirmed.

I'm currently at a loss what needs to happen here. You can work around with map_from_entries(), see below.

@hannes: do you think duckdb could implement the cast (STRUCT("key" *, "value" *)[] -> MAP(*, *)) directly?

con <- DBI::dbConnect(duckdb::duckdb())

DBI::dbExecute(con, "CREATE TABLE tbl (mp MAP(VARCHAR, VARCHAR));")
#> [1] 0
DBI::dbExecute(con, "INSERT INTO tbl VALUES (MAP {'a': 'b'})")
#> [1] 1

DBI::dbGetQuery(con, "DESCRIBE tbl")
#>   column_name           column_type null  key default extra
#> 1          mp MAP(VARCHAR, VARCHAR)  YES <NA>    <NA>  <NA>

df <- DBI::dbReadTable(con, "tbl")
tibble::as_tibble(df)
#> # A tibble: 1 × 1
#>   mp          
#>   <list>      
#> 1 <df [1 × 2]>
df$mp
#> [[1]]
#>   key value
#> 1   a     b

duckdb::duckdb_register(con, "df", df)
DBI::dbExecute(con, "INSERT INTO tbl SELECT map_from_entries(mp) FROM df")
#> [1] 1

df <- DBI::dbReadTable(con, "tbl")
tibble::as_tibble(df)
#> # A tibble: 2 × 1
#>   mp          
#>   <list>      
#> 1 <df [1 × 2]>
#> 2 <df [1 × 2]>
df$mp
#> [[1]]
#>   key value
#> 1   a     b
#> 
#> [[2]]
#>   key value
#> 1   a     b

^{Created on 2024-08-16 with reprex v2.1.0}