Would shell command join cause out of memory?
- by Hancy
I have two file to join.
FILE 1:
a A1
a A2
a A3
...
c C1
c C2
...
FILE 2:
a feature1_of_a
a feature2_of_a
...
a featureN_of_a
...
...
c feature1_of_c
c feature2_of_c
...
after join, i could get File like this:
A1 feature1_of_a
A2 feature1_of_a
A3 feature1_of_a
A1 feature2_of_a
A2 feature2_of_a
A3 feature2_of_a
...
A1 featureN_of_a
A2 featureN_of_a
A3 featureN_of_a
...
In order to do that: i wrote shell command join -11 -21 -o1.2,2.2 file1 file2.
But the problem is: number N might be huge. So if join read all feautre of a into memory at once, memory might not be enough.
I don't know how join is implemented. WQould the momery become a problem? If so, is there any way to get what I want?
