Split a file using windows batch script

Question

I have a csv file and i need to split it in to n files such that each split file should not exceed 100 mb. I need to achieve it in windows batch script. I tried the below way but its taking lot of time as my unsplit file is in GBs

@echo off
setlocal enableextensions enabledelayedexpansion
set count=1
set maxbytesize=100000000
set size=1
type NUL > output_1.csv

FOR /F  "tokens=*" %%i in (myfile.csv) do (
FOR /F "usebackq" %%A in ('!filename!_!count!.csv') do (
set size=%%~zA) 
if !size! LSS !maxbytesize! (
echo %%i>>!filename!_!count!.csv) else (
set /a count+=1 
echo %%i>>!filename!_!count!.csv 
))

please let me know if there is a better way to achieve this. I cant go to any other scripting languages as my server is windows

Answer 1

This would do the trick assuming your lines are roughly the same size.

Its advantage is that it is only a 2 pass solution, One for counting the lines and the other for printing them.

@rem echo off

@rem usage: batchsplit.bat <file-to-split> <size-limit>
@rem it will generate files named <file-to-split>.part_NNN

setlocal EnableDelayedExpansion

set FILE_TO_SPLIT=%1
set SIZE_LIMIT=%2

for /f %%s in ('dir /b %FILE_TO_SPLIT%') do set SIZE=%%~Zs
for /f %%c in ('type "%FILE_TO_SPLIT%"^|find "" /v /c') do set LINE_COUNT=%%c

set /a AVG_LINE_SIZE=%SIZE%/%LINE_COUNT%
set /a LINES_PER_PART=%SIZE_LIMIT%/%AVG_LINE_SIZE%

set "cmd=findstr /R /N "^^" %FILE_TO_SPLIT%"

for /f "tokens=1,2* delims=:" %%a in ('!cmd!') do @(
    set /a ccc = %%a / %LINES_PER_PART%
    echo %%b >> %FILE_TO_SPLIT%.part_!ccc!
)

save it as batchsplit.bat and run it using:

batchsplit.bat myfile.csv 100000000