'mlr cut' is very slow

[tooptoop4]

for a 5gb csv running 'mlr cut' for one column takes 5mins but only takes 30seconds with 'xsv select' (https://github.com/BurntSushi/xsv)

[johnkerl]

@tooptoop4 how many columns does the 5GB CSV have? (Also, if possible, can you link to the CSV file itself? No worries if not, but it'd be helpful).

The reason I ask about column-count is #1507 which will be in the next Miller release (6.12).

[aborruso]

Hi @johnkerl I have made a test using this big CSV https://opencoesione.gov.it/media/open_data//progetti_esteso_20231231.zip

QSV

time qsv select -d ";" OC_COD_CICLO progetti_esteso_20231231.csv > cut_qsv.csv

3.988 total, using qsv 0.123

Miller

time mlr --csv --ifs ";" --from progetti_esteso_20231231.csv cut -f OC_COD_CICLO >cut_mlr.csv

I have [2] 119700 killed, after 2:15.86 total, using mlr 6.11.0

duckdb

time duckdb --csv -c "select OC_COD_CICLO from read_csv('progetti_esteso_20231231.csv',delim=';')" >cut_duckdb.csv

1.382 total, using v0.10.0 20b1486d11

[aborruso]

1.382 total, using v0.10.0 20b1486d11

This is not a time to consider. Also duckdb fails and does not extract all 1977163 rows. Now I investigate further.

[aborruso]

In duckdb 0.10 there was this bug. It has been closed, but is not available in the compiled stable version.
I redid everything using duckbd pre version via python - pip3 install duckdb --pre --upgrade - and I have the right output in 1.6 seconds, using 0.10.1-dev1037.

import duckdb
import time  # Importa il modulo time

start_time = time.time()

query = """
COPY (select OC_COD_CICLO from read_csv('progetti_esteso_20231231.csv',delim=';')) to 'cut_duckdb.csv'
"""

duckdb.query(query)

end_time = time.time()


execution_time = end_time - start_time

print("Tempo di esecuzione: {:.2f} secondi".format(execution_time))

[johnkerl]

Thanks @tooptoop4 and @aborruso

Also I would note, xsv is well-known for speed; there is no assertion that Miller will outperform it for speed ...

[aborruso]

John I know, I love Miller, it is too comfortable, it is brilliant.
It is for me the best.

You were asking for an example and I included one that I am working with these days.

[johnkerl]

Indeed @aborruso I should have mentioned -- the example is quite sufficient -- thank you! :)

[aborruso]

Hi @johnkerl, using the new release - 6.12.0 - I have had no errors.

The processing time was 12:45.40 total.