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Full Discussion: Honey, I broke awk! (duplicate line removal in 30M line 3.7GB csv file)
Top Forums Shell Programming and Scripting Honey, I broke awk! (duplicate line removal in 30M line 3.7GB csv file) Post 302894671 by DGPickett on Wednesday 26th of March 2014 04:07:49 PM
Old 03-26-2014
If I recall correctly, cygwin and win7 not -64 is 32 bit, so 'a' may get too big for the address space of the awk process. Depending on ram size, it might eventually thrash a bit. The awk solution, a hash map, does not support parallism.

The classic, robust solution is 'sort -u <file_set>' but tends to be slower. You can parallelize the sort with a command of the form:
Code:
sort -mu <( sort -u <file_set_1> )  <( sort -u <file_set_2> ) <( sort -u <file_set_3> ) . . . .

where the nicer ksh or bash makes named pipes of the '<(...)' that run concurrently. I like twice the core count <(sort)'s, assuming 50% i/o delay. The final pass of the <(sort)'s feeds the sort -m merge parent.

ETL programs like Ab Initio know how to tell parallel processes to split up big files and process each part separately, even when the files are linefeed delimited (they all agree to search up (or down) for the dividing linefeed closest to N bytes down file). Does anyone know of a utility that can split a file this way (without reading it sequentially)? 'GNU parallel?'
 

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LEARN ABOUT SUNOS

mlib_vectorminimummag_u8c

mlib_VectorMinimumMag_U8C(3MLIB)			    mediaLib Library Functions				  mlib_VectorMinimumMag_U8C(3MLIB)

NAME

       mlib_VectorMinimumMag_U8C,  mlib_VectorMinimumMag_S8C,  mlib_VectorMinimumMag_S16C, mlib_VectorMinimumMag_S32C, mlib_VectorMinimumMag_F32C,
       mlib_VectorMinimumMag_D64C - find the first element with the minimum magnitude in a vector

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_VectorMinimumMag_U8C(mlib_u8 *min, const mlib_u8 *x, mlib_s32 n);

       mlib_status mlib_VectorMinimumMag_S8C(mlib_s8 *min, const mlib_s8 *x, mlib_s32 n);

       mlib_status mlib_VectorMinimumMag_S16C(mlib_s16 *min, const mlib_s16 *x, mlib_s32 n);

       mlib_status mlib_VectorMinimumMag_S32C(mlib_s32 *min, const mlib_s32 *x, mlib_s32 n);

       mlib_status mlib_VectorMinimumMag_F32C(mlib_f32 *min, const mlib_f32 *x, mlib_s32 n);

       mlib_status mlib_VectorMinimumMag_D64C(mlib_d64 *min, const mlib_d64 *x, mlib_s32 n);

DESCRIPTION

       Each of these functions finds the first element with the minimum magnitude in a complex vector, then puts the real and imaginary  parts	of
       it into min[0] and min[1], respectively.

PARAMETERS

       Each of the functions takes the following arguments:

       min	       Pointer to the first element with the minimum magnitude.

       x	       Pointer to the first element of the source vector.

       n	       Number of elements in the source vector.

RETURN VALUES

       Each of the functions returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_VectorMaximumMag_U8C(3MLIB), mlib_MatrixMaximumMag_U8C(3MLIB), mlib_MatrixMinimumMag_U8C(3MLIB), attributes(5)

SunOS 5.10							    9 Nov 2004					  mlib_VectorMinimumMag_U8C(3MLIB)
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