How to check between two files

[majesty250]

Could someone help me to figure it out my problem?
My fileA has 250K rows whit 2 fields like this
1234567 aabc
9873452 ac3f
...
My fileB has 1.2M rows with 3 or more fields like this:
I 5346282 ab4d 20020701
I 6759902 hhf3 20020901
...
I have to search the field1 of fileA in fileB and put in an external file: fields 1,2,4 of fileB and filed2 of fileA.
I know that using while cycle could be easier but it needs too much time. I'm looking for a shorter method.
Thanks and regards

 

[marsd]

You need to find all matching first columns in the two files, and when these match you need to write fld2 from the first and flds 1 , 2 and 4 from the second , is this right?


You could try this kind of approach.

awk ' BEGIN {
while ((getline array[a++] < file1) > 0) {
}
close(file1)
}
{

for (xx in array) {
cnt = split(array[xx],local,&quot; &quot;]
if (cnt) {
if ($1 == local[1]) {
print arr[2], $1, $2, $4 >> newfile
}
}
}
}

 

[majesty250]

marsd,

thanks for working on my stuff.
I decided to move to another direction. Your suggestion was too heavy for my machine, so as first step I grep out all records I need from the bigger file, than I gone ahead with awk having two files with same number of records.
Thanks for your effort.

majesty250

 

[marsd]

Yes, that's much simpler than the huge number of
times you will iterate over those entries otherwise.