PHP Performance issue with loops - php

Question

I use PHP to execute SQL queries and then extract timesheet data for a bunch of users.
Earlier it ran decently fast but has now slowed down drastically due to increase in number of Users and Tasks.
I have used a number of while, for loops. Not sure what I can optimize as calculations are iterative.
Appreciate if someone could look at the code and suggest some options.
private function processGETUSERTIMEREPORTDATA(SimpleXMLElement $xml, DBHandler $dbh) {
$from = Utils::convertToDatetime($this->clientDateFormat, $xml->FROM);
$to = Utils::convertToDatetime($this->clientDateFormat, $xml->TO);
$usercode = stripslashes(html_entity_decode($xml->UNCODE));
$this->logger->LogDebug("User List: " . $usercode);
$userArr = json_decode($usercode, TRUE);
$tChgMode = $xml->TASKCHGMODE;
$tType = $xml->TASKTYPE;
$timeSheetCategory = $xml->TIMESHEETCAT;
$totalChgHrsArr = array();
$totalNonChgHrsArr = array();
$totalGenNonChgHrsArr = array();
$totalChgDaysArr = array();
$totalDaysALeaveArr = array();
$totalDaysSLeaveArr = array();
$totalDaysCLeaveArr = array();
$totalExpensesArr = array();
// Set timesheet category table
if ($timeSheetCategory == "ALL") {
$tablename = array("tblChargeHours", "tblNonChargeHours", "tblFieldDays",
"tblNonChargeDays", "tblExpensesSheet", "tblGeneralNonChargeHours");
} else if ($timeSheetCategory == "Chargeable Hours") {
$tablename = array("tblChargeHours");
} else if ($timeSheetCategory == "Non Chargeable Hours") {
$tablename = array("tblNonChargeHours");
} else if ($timeSheetCategory == "Chargeable Days") {
$tablename = array("tblFieldDays");
} else if ($timeSheetCategory == "Leaves") {
$tablename = array("tblNonChargeDays");
} else if ($timeSheetCategory == "Expenses") {
$tablename = array("tblExpensesSheet");
} else if ($timeSheetCategory == "General Non Chargeable Hours") {
$tablename = array("tblGeneralNonChargeHours");
}
$arrlength = count($tablename);
$userCount = count($userArr);
for ($i = 0; $i < $userCount; $i++) {
for ($x = 0; $x < $arrlength; $x++) {
// Leaves table
if ($tablename[$x] == "tblNonChargeDays") {
// Annual Leave
$daysSum = 0;
$query = "SELECT Mo, Tu, We, Th, Fr, Sa, Su from " . $tablename[$x] . " WHERE (WeekEnding BETWEEN '$from' AND '$to') AND (TaskCode='1') AND (NameCode='" . $userArr[$i] . "')";
$hoursRes = $dbh->executeQuery($query);
if ($dbh->getQueryStatus()) {
while ($timerow = mysqli_fetch_assoc($hoursRes)) {
$daysSum += ($timerow['Mo'] + $timerow['Tu'] + $timerow['We'] + $timerow['Th'] + $timerow['Fr'] + $timerow['Sa'] + $timerow['Su']);
}
$totalDaysALeaveArr[] = $daysSum;
} else {
$this->logger->LogError("Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
return ResponseGenerator::generateNegativeRepsonse($this->reqName, "Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
}
// Sick Leave
$daysSum = 0;
$query = "SELECT Mo, Tu, We, Th, Fr, Sa, Su from " . $tablename[$x] . " WHERE (WeekEnding BETWEEN '$from' AND '$to') AND (TaskCode='2') AND (NameCode='" . $userArr[$i] . "')";
$hoursRes = $dbh->executeQuery($query);
if ($dbh->getQueryStatus()) {
while ($timerow = mysqli_fetch_assoc($hoursRes)) {
$daysSum += ($timerow['Mo'] + $timerow['Tu'] + $timerow['We'] + $timerow['Th'] + $timerow['Fr'] + $timerow['Sa'] + $timerow['Su']);
}
$totalDaysSLeaveArr[] = $daysSum;
} else {
$this->logger->LogError("Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
return ResponseGenerator::generateNegativeRepsonse($this->reqName, "Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
}
// Compassionate Leave
$daysSum = 0;
$query = "SELECT Mo, Tu, We, Th, Fr, Sa, Su from " . $tablename[$x] . " WHERE (WeekEnding BETWEEN '$from' AND '$to') AND (TaskCode='3') AND (NameCode='" . $userArr[$i] . "')";
$hoursRes = $dbh->executeQuery($query);
if ($dbh->getQueryStatus()) {
while ($timerow = mysqli_fetch_assoc($hoursRes)) {
$daysSum += ($timerow['Mo'] + $timerow['Tu'] + $timerow['We'] + $timerow['Th'] + $timerow['Fr'] + $timerow['Sa'] + $timerow['Su']);
}
$totalDaysCLeaveArr[] = $daysSum;
} else {
$this->logger->LogError("Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
return ResponseGenerator::generateNegativeRepsonse($this->reqName, "Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
}
// GeneralNonChgHours Table
} else if ($tablename[$x] == "tblGeneralNonChargeHours") {
$hoursSum = 0;
$query = "SELECT Mo, Tu, We, Th, Fr, Sa, Su from " . $tablename[$x] . " WHERE (WeekEnding BETWEEN '$from' AND '$to') AND (NameCode='" . $userArr[$i] . "')";
$hoursRes = $dbh->executeQuery($query);
if ($dbh->getQueryStatus()) {
while ($timerow = mysqli_fetch_assoc($hoursRes)) {
$hoursSum += ($timerow['Mo'] + $timerow['Tu'] + $timerow['We'] + $timerow['Th'] + $timerow['Fr'] + $timerow['Sa'] + $timerow['Su']);
}
$totalGenNonChgHrsArr[] = $hoursSum;
} else {
$this->logger->LogError("Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
return ResponseGenerator::generateNegativeRepsonse($this->reqName, "Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
}
}
} // end-for-tablename
} // end-for-usercode
if ($tChgMode == "ALL") {
if ($tType == "ALL") {
// $tChgMode = ALL && $tType = ALL
$tquery = "SELECT TCode, TType FROM tblTasks WHERE (TCreatedDate BETWEEN '$from' AND '$to')";
} else {
// $tChgMode = ALL && $tType = Sel
$tquery = "SELECT TCode, TType FROM tblTasks WHERE (TCreatedDate BETWEEN '$from' AND '$to') AND (TType='" . $tType . "') ORDER BY TCode ASC";
}
} else {
if ($tType == "ALL") {
// $tChgMode = Sel && $tType = ALL
$tquery = "SELECT TCode, TType FROM tblTasks WHERE (TCreatedDate BETWEEN '$from' AND '$to') AND (TChargeMode='" . $tChgMode . "') ORDER BY TCode ASC";
} else {
// $tChgMode = Sel && $tType = Sel
$tquery = "SELECT TCode, TType FROM tblTasks WHERE (TCreatedDate BETWEEN '$from' AND '$to') AND (TChargeMode='" . $tChgMode . "') AND (TType='" . $tType . "') ORDER BY TCode ASC";
}
}
$result = $dbh->executeQuery($tquery);
$tqueryArr = array(); // Store the query results
while ($row = mysqli_fetch_assoc($result)) {
$tqueryArr[] = $row;
}
for ($i = 0; $i < $userCount; $i++) {
$totalExpenses = 0;
$totalChgHrs = 0;
$totalNonChgHrs = 0;
$totalChgDays = 0;
foreach ($tqueryArr as $row) {
for ($x = 0; $x < $arrlength; $x++) {
$tCode = $row['TCode'];
// Expenses Table
if ($tablename[$x] == "tblExpensesSheet") {
$query = "SELECT FinalAmount from " . $tablename[$x] . " WHERE (WeekEnding BETWEEN '$from' AND '$to') AND (TaskCode='" . $tCode . "') AND (NameCode='" . $userArr[$i] . "')";
// $this->logger->LogDebug($query);
$hoursRes = $dbh->executeQuery($query);
if ($dbh->getQueryStatus()) {
while ($exprow = mysqli_fetch_assoc($hoursRes)) {
$totalExpenses += $exprow['FinalAmount'];
}
} else {
$this->logger->LogError("Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
return ResponseGenerator::generateNegativeRepsonse($this->reqName, "Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
}
// Other Tables
} else {
$query = "SELECT Mo, Tu, We, Th, Fr, Sa, Su from " . $tablename[$x] . " WHERE (WeekEnding BETWEEN '$from' AND '$to') AND (TaskCode='" . $tCode . "') AND (NameCode='" . $userArr[$i] . "')";
$hoursRes = $dbh->executeQuery($query);
$totalHours = 0;
if ($dbh->getQueryStatus()) {
while ($timerow = mysqli_fetch_assoc($hoursRes)) {
$hoursSum = ($timerow['Mo'] + $timerow['Tu'] + $timerow['We'] + $timerow['Th'] + $timerow['Fr'] + $timerow['Sa'] + $timerow['Su']);
$totalHours += $hoursSum;
}
switch ($tablename[$x]) {
case "tblChargeHours":
$totalChgHrs += $totalHours;
break;
case "tblNonChargeHours":
$totalNonChgHrs += $totalHours;
break;
case "tblFieldDays":
$totalChgDays += $totalHours;
break;
default:
}
} else {
$this->logger->LogError("Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
return ResponseGenerator::generateNegativeRepsonse($this->reqName, "Unable to generate Timesheet report data. Q : " . $query . " E : " . $dbh->getQueryMessage());
}
}
} // end-for
} // end-while
$totalExpensesArr[] = $totalExpenses;
$totalChgHrsArr[] = $totalChgHrs;
$totalNonChgHrsArr[] = $totalNonChgHrs;
$totalChgDaysArr[] = $totalChgDays;
} // end-for-usercode
$xmlop = new SimpleXMLElement('<RESPONSE/>');
$xmlop->addChild("REQUESTNAME", $this->reqName);
$xmlop->addChild("REQUESTSTATUS", "SUCCESS");
$rowxml = $xmlop->addChild("ROW");
$rowxml->addChild("USERCODE", json_encode($userArr));
$rowxml->addChild("CHGHOURS", json_encode($totalChgHrsArr));
$rowxml->addChild("NONCHGHOURS", json_encode($totalNonChgHrsArr));
$rowxml->addChild("GENNONCHGHOURS", json_encode($totalGenNonChgHrsArr));
$rowxml->addChild("FIELDDAYS", json_encode($totalChgDaysArr));
$rowxml->addChild("ANNLEAVE", json_encode($totalDaysALeaveArr));
$rowxml->addChild("SICKLEAVE", json_encode($totalDaysSLeaveArr));
$rowxml->addChild("COMPLEAVE", json_encode($totalDaysCLeaveArr));
$rowxml->addChild("EXPENSES", json_encode($totalExpensesArr));
return $xmlop->asXML();
}

Answer 1

Apart from the complicated code, you will probably find that you have an indexing (or lack of) issue.
Find every field that is used in any of the WHERE clauses and create an index for it.
It's quite possible that if you have a growing database that is gradually getting slower, it could be an indexing problem.