Merging big data.frame

Hi all,

I am trying to merge 2 big data.frame. The problem is merge is memory
intensive so R is going out of memory error: cannot allocate vector of
size
360.1 Mb. To overcome this, I am exploring option of using data.table
package. But its not helping in term of memory as merge in data.table
is
fast but not memory efficient. Similar error is coming.
My inputs are
inp1
V1 V2
1  a i1
2  a i2
3  a i3
4  a i4
5  b i5
6  c i6

inp2
 V1 V2
1  a  x
2  b  x
3  a  y
4  c  z

I want  merge(x=inp1, y=inp2, by.x="V1", by.y="V1")
so the output

V1 V2.x V2.y
1   a   i1    x
2   a   i1    y
3   a   i2    x
4   a   i2    y
5   a   i3    x
6   a   i3    y
7   a   i4    x
8   a   i4    y
9   b   i5    x
10  c   i6    z

Is there a way to do this without using merge in data.table? or Is
there
any other solution to do this in more efficient and less memory ?

thanks
avi

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