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The code for constructing
List(v::Vector{String})
is extremely slow, causing problems when writing Feather files of dataframes that are string heavy (for instance, it took me 770s to write a 3.2GB file with a large number of address fields, whereas python can write the same file in 12s). It looks like the problem comes from the code that encodes the strings as vectors ofUInt8
.I played around with it, and it looks like you can get nearly a 20X speedup by writing a specialized method to handle vectors of strings as in this PR:
I'm not super familiar with the internals of string encodings, but this seems to work on my local machine (and passes all the tests). I've tried it out with Feather as well on some real world datasets, and everything seems to work properly.