Linux: awk - Grouping Data in a file

Consider the below file:

# cat test.csv
aa 1 qwer
ab 2 tyui
aa 3 poiu
ab 2 mnb
bb 1 njio
ba 2 njtwe

test.csv  is a tab separated file with 3 columns. 

Here, I want to segregate the whole lines with matching 1st and 2nd columns into separate files. 

Like below:

# cat file_bb_1.csv

bb 1 njio

# cat file_ba_2.csv

ba 2 njtwe

# cat file_ab_2.csv

ab 2 tyui

ab 2 mnb

# cat file_aa_3.csv

aa 3 poiu

# cat file_aa_1.csv

aa 1 qwer

Though you can do this manually, think of a file with more than million lines.

Here, 'awk', being an powerful data manipulation tool,comes to our help. 

Below is the command we can use:

#cat test.csv | awk '{a=$1;b=$2; print $0 >> "file_" a "_" b ".csv"}'

[You can give any name instead of 'file_']