Perl Monks,

I have a routine to update a number of rows for one column in a database table. I want to speed this up though because at the moment it runs an SQL update for each row. For approx 10000 it takes 2 secs. 

sub process_urlhits_update{
    my $sql1 = qq {UPDATE url_table SET hits};
    my $sql2 = qq {WHERE url};
    my $sql;
    foreach my $url ( keys %urlhits_update ){
        $sql= qq { $sql1=$urlhits_update{$url} $sql2="$url" };
        my $sth = $dbh->prepare( $sql );
        $sth->execute();
        $urlid_hash{$url}=get_urlid($url) if ! defined $urlid_hash{$ur
+l};
        delete $urlhits_update{$url};
    }
}

[download]

I tried changing the code to write to a file and then run one SQL command to LOAD FILE. This runs quicker at about 1.3 secs for 10000 rows: 

sub process_urlhits_update{
    my $sql1 = qq {\nUPDATE url_table SET hits};
    my $sql2 = qq {WHERE url};
    my $sql;
    open(FH,">/tmp/updates.txt")||die("could not open updates file");

    foreach my $url ( keys %urlhits_update ){
        $sql .= qq { $sql1=$urlhits_update{$url} $sql2="$url" };
        $urlid_hash{$url}=get_urlid($url) if ! defined $urlid_hash{$ur
+l};
        delete $urlhits_update{$url};
    }
    print FH $sql;
    $sql="LOAD DATA LOCAL INFILE '/tmp/updates.txt' INTO TABLE url_tab
+le";
    my $sth = $dbh->prepare( $sql );
    $sth->execute();
}

[download]

However, my 2 routines which do bulk SQL inserts only take 0.26 secs.

Is there anything I can do to improve my code above? For example, can I run LOAD FILE without actually writing to disk ? or can you do bulk updates?

Thanks as always for your wisdom.

js.

In reply to speedy update routine by js1

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