RaqForum 41 No.
151 View  • 
     ...

Process a large csv file with parallel processing

 

A csv file stores a large amount orders data.

OrderID,Client,SellerID,Amount,OrderDate

1,SPLI,219,9173,01/17/2022

2,HU,110,6192,10/01/2020

3,SPL,173,5659,04/23/2020

4,OFS,7,3811,02/05/2023

5,ARO,146,3752,08/27/2021

6,SRR,449,10752,05/27/2022

7,SJCH,326,11719,01/18/2022

8,JDR,3,11828,12/09/2021

Use Java to process this file: Find orders whose amounts are between 3,000 and 5,000, group them by customers, and sum order amounts and count orders.

Client

amt

cnt

ARO

11948382

2972

BDR

11720848

2933

BON

11864952

2960

BSF

11947734

2980

CHO

11806401

2968

CHOP

11511201

2877

D

11491452

2876

DSG

11672114

2910

DSGC

11656479

2918

Write the following SPL statement:

=file("d:/OrdersBig.csv").cursor@mtc(;8).select(Amount>=3000 && Amount<5000).groups(Client;sum(Amount):amt,count(1):cnt)

cursor() function parses a large file that cannot fit into the memory; by default, it performs the serial computation. @m option enables multithreaded data retrieval; 8 is the number of parallel threads; @t option enables importing the first line as column titles; and @c option enables using comma as the separator.

Read How to Call a SPL Script in Java to find how to integrate SPL into a Java application.
Source:https://stackoverflow.com/questions/70586145/how-to-read-a-specific-column-of-a-row-from-a-csv-file-in-java


 
 •  151 View  •