How to increase efficiency of perl script which uses sqlplus - sql

Question

I have this perl script which takes the data from sqlplus database... this database adds a new entry every time when there is a change in the value of state for a particular serial number. Now we need to pick the entries at every state change and prepare a csv file with old state, new state and other fields. db table sample.
SERIALNUMBER STATE AT OPERATORID SUBSCRIBERID TRANSACTIONID
51223344558899 Available 20081008T10:15:47 vsuser
51223344558857 Available 20081008T10:15:49 vsowner
51223344558899 Used 20081008T10:20:25 vsuser
51223344558860 Stolen 20081008T10:15:49 vsanyone
51223344558857 Damaged 20081008T10:50:49 vsowner
51223344558899 Damaged 20081008T10:50:25 vsuser
51343253335355 Available 20081008T11:15:47 vsindian
my script:
#! /usr/bin/perl
#use warnings;
use strict;
#my $circle =
#my $schema =
my $basePath = "/scripts/Voucher-State-Change";
#my ($sec, $min, $hr, $day, $month, $years) = localtime(time);
#$years_+=1900;$mont_+=1;
#my $timestamp=sprintf("%d%02d%02d",$years,$mont,$moday);
sub getDate {
my $daysago=shift;
$daysago=0 unless ($daysago);
#my #months=qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time-(86400*$daysago));
# YYYYMMDD, e.g. 20060126
return sprintf("%d%02d%02d",$year+1900,$mon+1,$mday);
}
my $filedate=getDate(1);
#my $startdate="${filedate}T__:__:__";
my $startdate="20081008T__:__:__";
print "$startdate\n";
##### Generating output file---
my $outputFile = "${basePath}/VoucherStateChangeReport.$filedate.csv";
open (WFH, ">", "$outputFile") or die "Can't open output file $outputFile for writing: $!\n";
print WFH "VoucherSerialNumber,Date,Time,OldState,NewState,UserId\n";
##### Generating log file---
my $logfile = "${basePath}/VoucherStateChange.$filedate.log";
open (STDOUT, ">>", "$logfile") or die "Can't open logfile $logfile for writing: $!\n";
open (STDERR, ">>", "$logfile") or die "Can't open logfile $logfile for writing: $!\n";
print "$logfile\n";
##### Now login to sqlplus-----
my $SQLPLUS='/opt/oracle/product/11g/db_1/bin/sqlplus -S system/coolman7#vsdb';
`$SQLPLUS \#${basePath}/VoucherQuery1.sql $startdate> ${basePath}/QueryResult1.txt`;
open (FH1, "${basePath}/QueryResult1.txt");
while (my $serial = <FH1>) {
chomp ($serial);
my $count = `$SQLPLUS \#${basePath}/VoucherQuery2.sql $serial $startdate`;
chomp ($count);
$count =~ s/\s+//g;
#print "$count\n";
next if $count == 1;
`$SQLPLUS \#${basePath}/VoucherQuery3.sql $serial $startdate> ${basePath}/QueryResult3.txt`;
# print "select * from sample where SERIALNUMBER = $serial----\n";
open (FH3, "${basePath}/QueryResult3.txt");
my ($serial_number, $state, $at, $operator_id);
my $count1 = 0;
my $old_state;
while (my $data = <FH3>) {
chomp ($data);
#print $data."\n";
my #data = split (/\s+/, $data);
my ($serial_number, $state, $at, $operator_id) = #data[0..3];
#my $serial_number = $data[0];
#my $state = $data[1];
#my $at = $data[2];
#my $operator_id = $data[3];
$count1++;
if ($count1 == 1) {
$old_state = $data[1];
next;
}
my ($date, $time) = split (/T/, $at);
$date =~ s/(\d{4})(\d{2})(\d{2})/$1-$2-$3/;
print WFH "$serial_number,$date,$time,$old_state,$state,$operator_id\n";
$old_state = $data[1];
}
}
close(WFH);
query in VoucherQuery1.sql:
select distinct SERIALNUMBER from sample where AT like '&1';
query in VoucherQuery2.sql:
select count(*) from sample where SERIALNUMBER = '&1' and AT like '&2';
query in VoucherQuery2.sql:
select * from sample where SERIALNUMBER = '&1' and AT like '&2';
and my sample output:
VoucherSerialNumber,Date,Time,OldState,NewState,UserId
51223344558857,2008-10-08,10:50:49,Available,Damaged,vsowner
51223344558899,2008-10-08,10:20:25,Available,Used,vsuser
51223344558899,2008-10-08,10:50:25,Used,Damaged,vsuser
Script is working pretty fine. But problem is that actual db table has millions of records for a specific day... and therefore it is raising performance issues... could you please advise how can we improve the efficiency of this script in terms of time & load. Only restriction is that I can't use DBI module for this...
Also in case of any error in the sql queries, error msg is coming to QueryResult?.txt files. I want to handle and receive these errors in my log file. how this can be accomplished? thanks

Answer 1

I think you need to tune your query. A good starting point is to use the EXPLAIN PLAN, if it is an Oracle database.