<[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Hi all,
Hello,
>
> I have two database tables, one is local and one is on a WAN. They are
> supposed
> to be in-sync but they at the moment, they are not. There are 8million+
> plus
> rows on this table.
>
> I tried to do SELECT EMPNO FROM EMP WHERE EMPNO NOT IN ( SELECT EMPNO FROM
> [EMAIL PROTECTED] ), leave that running for hours and all thru the night and
> guess
> what, am still waiting for the result to come out ...
>
> So what I decided is I want to extract the records into a flat file and
> then
> write a Perl script to skim thru each line and check whether it exists on
> the
> other file. While there will be 8million+ lines, the file will not be big
> beacuse am only extracting one-column from the table.
>
> Does anyone have an existing Perl code that does a similar thing like this
> already? It will be much appreciated if you can send it to me and then I
> will
> just modify it accordingly.
>
> Example logic that I have is this:
>
> FILE1:
> MICKEY
> MINNIE
> DONALD
> GOOFY
> PLUTO
>
> FILE2:
> MICKEY
> MINNIE
> DONALD
> GOOFY
> PLUTO
> BUGS-BUNNY
>
This will work, based on you given data
use strict;
use warnings;
my @file2 = qw/mickey minnie donald goofy pluto /;
my @file1 = qw /mickey minnie donald goofy pluto bunny/;
my %hash = map { $_ => undef } @file2;
while(<@file1>) {
unless(exists $hash{$_}) {
print $_, "\n";
}
}
output:
bunny
caveats:
This will only print out the element that were present on file1 and were
not on file2,
and i'm also a beginner.
> So search FILE1 for all line entries of FILE2 then output whoever does not
> exist
> into FILE3. So after running the script, I should have ...
>
> FILE3:
> BUGS-BUNNY
>
> What I currently have is that I read all of FILE2's entries into an array?
> Read
> FILE1 one line at a time using m/// and if there is no m///, print that to
> FILE3.
>
> It seems to work fine for 1000 lines of entries, but am not particularly
> sure
> how long will that take for 8million+ rows, not even sure if I can create
> an
> array to contain 8million+ plus rows, if I can't, then am back to doing
> this on
> the database instead. Another option am looking at is just to read FILE1
> one
> line at a time and do a grep "$string_to_search" FILE2 but I do not know
> how to
> do a grep-like syntax against a file on Perl especially if the search
> string is
> a variable.
>
> Why I prefer using a script is so am not putting loads into the database
> not to
> mention that I can put more logic into the script than on the SQL
> statement.
>
> Any advise or other options will be very much appreciated .... Thanks in
> advance.
>
>
welcome, HTH.
/joseph
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