nanoarrow_array_stream or nanoarrow_array?

[eitsupi]

The DBI package documentation and the DBItest shows that methods like dbGetQueryArrow return nanoarrow_array_stream, but the README of this repository seems to return nanoarrow_array.
Is this intentional?

adbi/README.md

Lines 98 to 99 in f56d677

	dbGetQueryArrow(con, "SELECT * from swiss WHERE Agriculture < 40")
	#> <nanoarrow_array struct[16]>

[nbenn]

@eitsupi sorry for the slow response. We're still a bit unclear on the DBI API here. As soon as that is fixed (i.e. CRAN released), adbi should fall in line.

cc @krlmlr

[eitsupi]

Any update on this?

I tried to implement Arrow-related methods to polarssql, but the return value type is not listed in the documentation and I cannot see the implementation method.

[krlmlr]

The README now returns a nanoarrow array stream. The documentation at https://dbi.r-dbi.org/dev/reference/dbGetQueryArrow.html isn't very specific, intentionally. DBI's implementation for the fallback is accessible like this:

DBI:::dbGetQueryArrow_DBIConnection_character
#> function(conn, statement, ...) {
#>   rs <- dbSendQueryArrow(conn, statement, ...)
#>   on.exit(dbClearResult(rs))
#> 
#>   dbFetchArrow(rs, ...)
#> }
#> <environment: namespace:DBI>
DBI:::dbFetchArrow_DBIResultArrow
#> function(res, ...) {
#>   chunk <- dbFetchArrowChunk_DBIResultArrow(res)
#>   # Corner case: add empty chunk only for zero rows, for schema
#>   if (chunk$length == 0) {
#>     return(nanoarrow::basic_array_stream(
#>       list(),
#>       schema = nanoarrow::infer_nanoarrow_schema(chunk),
#>       validate = FALSE
#>     ))
#>   }
#> 
#>   out <- list(chunk)
#>   repeat {
#>     chunk <- dbFetchArrowChunk_DBIResultArrow(res)
#>     if (chunk$length == 0) {
#>       return(nanoarrow::basic_array_stream(
#>         out,
#>         schema = nanoarrow::infer_nanoarrow_schema(out[[1]]),
#>         validate = FALSE
#>       ))
#>     }
#>     out <- c(out, list(chunk))
#>   }
#> }
#> <environment: namespace:DBI>

^{Created on 2023-12-31 with reprex v2.0.2}

[eitsupi]

I think this has been fixed, thanks!