I am writing a Swift language interface to the Apache Arrow GLib C bindings.
I am currently successfully putting Swift arrays into GArrays into GTables into
feather files on disk:
func saveGTableToFeather(_ gTable: UnsafeMutablePointer<GArrowTable>,
outputPath: String) throws {
var error: UnsafeMutablePointer<GError>? = nil
// TODO: How do I turn on compression?
let properties = garrow_feather_write_properties_new()
let path = outputPath.cString(using: .utf8)
let output = garrow_file_output_stream_new(path, 0, &error)
if let error = error {
let errorString: String = String(cString: error.pointee.message)
g_error_free(error)
g_object_unref(output)
g_object_unref(properties)
throw ArrowError.invalidTableCreation(errorString)
}
let result: gboolean = garrow_table_write_as_feather(gTable,
GARROW_OUTPUT_STREAM(output), properties, &error)
if result == 0 {
let errorString: String = error != nil ? String(cString:
error!.pointee.message) : ""
g_error_free(error)
g_object_unref(output)
g_object_unref(properties)
throw ArrowError.invalidTableCreation(errorString)
}
g_object_unref(output)
g_object_unref(properties)
}
When I run file myData.feather on Ubuntu 18.04, it doesn’t indicate any kind of
compression, so the files I’m saving may not be compressed at all.
You can see I’ve created a new GArrowFeatherWriteProperties with
garrow_feather_write_properties_new , but how do I set the compression level? I
see it is meant to have a compression property based on the docs here (
https://arrow.apache.org/docs/c_glib/arrow-glib/GArrowTable.html#GArrowFeatherWriteProperties--compression
). When I attempt to set properties.compression (In Swift this is likely
properties.pointee.compression ), I get a compiler error that it has no such
property. Do I need to make a cast? Is there any example code of setting the
compression on a GArrowFeatherWriteProperties ?
Thank you,
Xander
