Perl -> Avoiding unnecessary method calls - perl

Question

I have to read log files of a store. The log shows the item id and the word "sold" after it. So I made a script to read this file, counting how many times a word "sold" appears for each item id. Turns out that there are many "owners" for the items. That is, there is a relation between "owner_id" (a data in my DB) and "item_id". Im interested in knowing how many items owners sell per day, so I create a "%item_id_owner_map":
my %item_id_sold_times;
my %item_id_owner_map;
open my $infile, "<", $file_location or die("$!: $file_location");
while (<$infile>) {
if (/item_id:(\d+)\s*,\s*sold/) {
my $item_id = $1;
$item_id_sold_times{$item_id}++;
my $owner_ids =
Store::Model::Map::ItemOwnerMap->fetch_by_keys( [$item_id] )
->entry();
for my $owner_id (#$owner_ids) {
$item_id_owner_map{$owner_id}++;
}
}
}
close $infile;
The "Store::Model::Map::ItemOwnerMap->fetch_by_keys( [$item_id] )->entry();" method takes item_id or ids as input, and gives back owner_id as output.
Everything looks great but actually, you will see that every time Perl finds a regex match (that is, every time the "if" condition applies), my script will call "Store::Model::Map::ItemOwnerMap->fetch_by_keys" method, which is very expensive, as these log files are very very long.
Is there a way to make my script more efficient? If possible, I only want to call my Model method once.
Best!

Answer 1

Separate your logic into two loops:
while (<$infile>) {
if (/item_id:(\d+)\s*,\s*sold/) {
my $item_id = $1;
$item_id_sold_times{$item_id}++;
}
}
my #matched_items_ids = keys %item_id_sold_times;
my $owner_ids =
Store::Model::Map::ItemOwnerMap->fetch_by_keys( \#matched_item_ids )
->entry();
for my $owner_id (#$owner_ids) {
$item_id_owner_map{$owner_id}++;
}
I don't know if the entry() call is correct, but the general shape of that code should do it for you.
In general databases are good at fetching sets of rows, so you're right to minimise the calls to fetch from the DB.