Howdy,

I am seeing some issues when trying to render a web page that contains a large table of data. I chatted a bit yesterday evening about this in the chat box and did some checking to see where the most time is spent.

It appears the time hog is occuring when processing my foreach loop. I have simplified my code and it is below.

In summary, I have three pieces of SQL I run (see Lori713's scratchpad), and the total rows returned for all three is approx. 75,000. On smaller project numbers (say 500 rows), once I get through my foreach loop, the three datasets are nicely smooshed together to form one row for each project number and works beautifully if a bit more slowly than I would like:

project ID        Bud amount       Act amount        Enc amount

I noticed that it is taking a very long time to process each row. Could this be because of the sort in the foreach? Does putting
 foreach $key ( sort keys %ctrl_tbl )
cause it to sort each time through the control table, or is the cost for the sort observed only the first time through? 
#!/usr/local/bin/perl5_8
use strict;
use ncw_com_library;            # contains common subs (commify, timeo
+ut, etc.)
use HTML::Template;
use Time::Local;
use DBI;
use CGI ':standard';
my $CGI = CGI->new;

# Clear buffers and set up web page (required)
$|=1;
open STDERR, ">&STDOUT";

# SNIP   there are ~25,000 unique keys in my control table and I have 
+snipped
# out the SQL and database calls that generate my control table datase
+t for
# those since they are returning results in a timely fashion based on 
# timestamps printed while fetching and executing SQL.

my ($key, %col_cbud, %col_encu, %col_fytd, %col_proj, %ctrl_tbl, @loop
+_data);

foreach $key ( sort keys %ctrl_tbl )
    { my %row_data;

# Gimme a timestamp so I can see how long each row takes
my ( $sec1,$min1,$hour1,$mday1,$mon1,$year1,$wday1,$yday1,$isdst1 ) = 
+localtime;
print "during foreach loop hour min sec $hour1 $min1 $sec1 xxx key is 
+$key <br>";

      $row_data{col_proj}   = $key;
      $row_data{col_cbud}   = $col_cbud{$key};
      $row_data{col_fytd}   = $col_fytd{$key};
      $row_data{col_encu}   = $col_encu{$key};

      # Add each hash row to loop for template
      push(@loop_data, \%row_data);
    }

# Pass parameters and variable values from @loop arrays to template; p
+rint report
$template->param(
passdata       => \@loop_data,
                );

print $template->output();

[download]
So far, as I try to run the report, my timestamp prints look like this (the first 100 rows): 
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxbefore foreach loop hour min sec 
+11 13 44
during foreach loop hour min sec 11 13 45 xxx key is 649001 
during foreach loop hour min sec 11 14 43 xxx key is 649001-60426-F 

SNIP

during foreach loop hour min sec 12 3 44 xxx key is 660062-05279 
during foreach loop hour min sec 12 4 19 xxx key is 660062-15279

[download]
We are beginning to see more and more issues with pages timing out as our co-workers ask for more sophisticated programs (I work at a public university). I think we need to start looking into alternative ways to address this issue and come up with a coding method to incorporate into the applications we're writing.

I would appreciate any suggestions or ideas as to what might be causing such a large block of time being spent on each row, and for any ideas about future coding that can take into account rendering large data tables on the browser.

Thanks!

In reply to Foreach loop takes a long time to process and my report times out before page is rendered by Lori713

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