..F....... [ZBX-18086] fixed missing data selection in data overview and trigger overview screens

* commit '7c41c9178d1cf1936f040b42e34e88b4bbba4461':
  ..F....... [ZBX-18086] fixed applying of limits for data overview
  ..F....... [ZBX-18086] simlified code
  ..F....... [ZBX-18086] improved performance
  ..F....... [ZBX-18086] simplified code; removed dead code
  ..F....... [ZBX-18086] fixed coding style
  ..F....... [ZBX-18086] fixed item grouping in data overview widget
  ..F....... [ZBX-18086] fixed selection of triggers to display in triggers overview
  ..F....... [ZBX-18086] fixed undefined offset error
  ..F....... [ZBX-18086] fixed unneeded references for function arguments
  ..F....... [ZBX-18086] fixed trigger grouping
  ..F....... [ZBX-18086] fixed item naming in data overview report header
  ..F....... [ZBX-18086] fixed nested API request
  .D........ [ZBX-18086] fixed changelog
  ..F....... [ZBX-18086] fixed trigger overview data selection
  ..F....... [ZBX-18086] fixed undefined index error in data overview screen item
  ..F....... [ZBX-18086] fixed items to be grouped by name instead of key in data overview screen
  ..F....... [ZBX-18086] fixed warning mesage not be displayed in data overview report
  ..F....... [ZBX-18086] fixed hostid selection in getDataOverviewItems function
  ..F....... [ZBX-18086] fixed missing data selection in data overview screen

(cherry picked from commit 9e4febe1a3c1b63bdcc5ae9671dde0571f0a61a6)

12 files changed, 266 insertions, 358 deletions

diff --git a/ui/app/controllers/CControllerWidgetDataOverView.php b/ui/app/controllers/CControllerWidgetDataOverView.php
index 7407fa87175..33463e25e08 100644
--- a/ui/app/controllers/CControllerWidgetDataOverView.php
+++ b/ui/app/controllers/CControllerWidgetDataOverView.php
@@ -37,18 +37,7 @@ class CControllerWidgetDataOverView extends CControllerWidget {
 		$groupids = $fields['groupids'] ? getSubGroups($fields['groupids']) : null;
 		$hostids = $fields['hostids'] ? $fields['hostids'] : null;
 
-		if ($fields['style'] == STYLE_TOP) {
-			list($db_items, $db_hosts, $items_by_name, $has_hidden_data) = getDataOverviewTop($groupids, $hostids,
-				$fields['application']
-			);
-		}
-		else {
-			list($db_items, $db_hosts, $items_by_name, $has_hidden_data) = getDataOverviewLeft($groupids, $hostids,
-				$fields['application']
-			);
-		}
-
-		$visible_items = getDataOverviewCellData($db_hosts, $db_items, $items_by_name, $fields['show_suppressed']);
+		[$items, $hosts, $has_hidden_data] = getDataOverview($groupids, $hostids, $fields);
 
 		$this->setResponse(new CControllerResponseData([
 			'name' => $this->getInput('name', $this->getDefaultHeader()),
@@ -56,9 +45,8 @@ class CControllerWidgetDataOverView extends CControllerWidget {
 			'application' => $fields['application'],
 			'show_suppressed' => $fields['show_suppressed'],
 			'style' => $fields['style'],
-			'visible_items' => $visible_items,
-			'db_hosts' => $db_hosts,
-			'items_by_name' => $items_by_name,
+			'items' => $items,
+			'hosts' => $hosts,
 			'has_hidden_data' => $has_hidden_data,
 			'user' => [
 				'debug_mode' => $this->getDebugMode()
diff --git a/ui/app/controllers/CControllerWidgetTrigOverView.php b/ui/app/controllers/CControllerWidgetTrigOverView.php
index 339134866a7..c6e5877dd4e 100644
--- a/ui/app/controllers/CControllerWidgetTrigOverView.php
+++ b/ui/app/controllers/CControllerWidgetTrigOverView.php
@@ -61,9 +61,9 @@ class CControllerWidgetTrigOverView extends CControllerWidget {
 			'hostids' => $fields['hostids'] ? $fields['hostids'] : null
 		];
 
-		list($data['db_hosts'], $data['db_triggers'], $data['dependencies'], $data['triggers_by_name'],
-			$data['hosts_by_name'], $data['exceeded_hosts'], $data['exceeded_trigs']
-		) = getTriggersOverviewData(getSubGroups($fields['groupids']), $fields['application'], $host_options,
+		[$data['db_hosts'], $data['db_triggers'], $data['dependencies'], $data['triggers_by_name'],
+			$data['hosts_by_name'], $data['exceeded_limit']
+		] = getTriggersOverviewData(getSubGroups($fields['groupids']), $fields['application'], $host_options,
 			$trigger_options, $problem_options
 		);
 
diff --git a/ui/app/partials/dataoverview.table.left.php b/ui/app/partials/dataoverview.table.left.php
index 2f368154ed1..b8a900cc8e2 100644
--- a/ui/app/partials/dataoverview.table.left.php
+++ b/ui/app/partials/dataoverview.table.left.php
@@ -26,27 +26,29 @@ $table = (new CTableInfo())
 	->makeVerticalRotation()
 	->setHeadingColumn(0);
 
-$headings[] = _('Hosts');
-foreach ($data['items_by_name'] as $name => $hostid_to_itemid) {
-	$headings[] = (new CColHeader($name))
-		->addClass('vertical_rotation')
-		->setTitle($name);
+$header = [_('Hosts')];
+foreach ($data['items'] as $item_name => $item_data) {
+	foreach ($item_data as $columns_data) {
+		$header[] = (new CColHeader($item_name))
+			->addClass('vertical_rotation')
+			->setTitle($item_name);
+	}
 }
+$table->setHeader($header);
 
-$table->setHeader($headings);
-
-foreach ($data['db_hosts'] as $hostid => $host) {
+foreach ($data['hosts'] as $hostid => $host) {
 	$name = (new CLinkAction($host['name']))->setMenuPopup(CMenuPopupHelper::getHost($hostid));
 	$row = [(new CColHeader($name))->addClass(ZBX_STYLE_NOWRAP)];
 
-	foreach ($data['items_by_name'] as $hostid_to_itemid) {
-		if (!array_key_exists($host['hostid'], $hostid_to_itemid)) {
-			$row[] = new CCol();
-		}
-		else {
-			$itemid = $hostid_to_itemid[$host['hostid']];
-			$item = $data['visible_items'][$itemid];
-			$row[] = getItemDataOverviewCell($item, $item['trigger']);
+	foreach ($data['items'] as $item_name => $columns_data) {
+		foreach ($columns_data as $column_data) {
+			if (array_key_exists($host['name'], $column_data)) {
+				$item = $column_data[$host['name']];
+				$row[] = getItemDataOverviewCell($item, $item['trigger']);
+			}
+			else {
+				$row[] = new CCol();
+			}
 		}
 	}
 
diff --git a/ui/app/partials/dataoverview.table.top.php b/ui/app/partials/dataoverview.table.top.php
index 38a82ef15ef..d4bb0639253 100644
--- a/ui/app/partials/dataoverview.table.top.php
+++ b/ui/app/partials/dataoverview.table.top.php
@@ -27,7 +27,7 @@ $table = (new CTableInfo())
 	->setHeadingColumn(0);
 
 $headings[] = _('Items');
-foreach ($data['db_hosts'] as $host) {
+foreach ($data['hosts'] as $host) {
 	$headings[] = (new CColHeader($host['name']))
 		->addClass('vertical_rotation')
 		->setTitle($host['name']);
@@ -35,21 +35,21 @@ foreach ($data['db_hosts'] as $host) {
 
 $table->setHeader($headings);
 
-foreach ($data['items_by_name'] as $name => $hostid_to_itemid) {
-	$row = [(new CColHeader($name))->addClass(ZBX_STYLE_NOWRAP)];
-
-	foreach ($data['db_hosts'] as $hostid => $host) {
-		if (!array_key_exists($host['hostid'], $hostid_to_itemid)) {
-			$row[] = new CCol();
-		}
-		else {
-			$itemid = $hostid_to_itemid[$host['hostid']];
-			$item = $data['visible_items'][$itemid];
-			$row[] = getItemDataOverviewCell($item, $item['trigger']);
+foreach ($data['items'] as $item_name => $item_data) {
+	foreach ($item_data as $items) {
+		$row = [(new CColHeader($item_name))->addClass(ZBX_STYLE_NOWRAP)];
+		foreach ($data['hosts'] as $host) {
+			if (array_key_exists($host['name'], $items)) {
+				$item = $items[$host['name']];
+				$row[] = getItemDataOverviewCell($item, $item['trigger']);
+			}
+			else {
+				$row[] = new CCol();
+			}
 		}
-	}
 
-	$table->addRow($row);
+		$table->addRow($row);
+	}
 }
 
 if ($data['has_hidden_data']) {
diff --git a/ui/app/partials/trigoverview.table.left.php b/ui/app/partials/trigoverview.table.left.php
index 66f13c76095..c21166b2954 100644
--- a/ui/app/partials/trigoverview.table.left.php
+++ b/ui/app/partials/trigoverview.table.left.php
@@ -57,7 +57,7 @@ foreach ($data['hosts_by_name'] as $hostname => $hostid) {
 	$table->addRow($row);
 }
 
-if ($data['exceeded_hosts'] || $data['exceeded_trigs']) {
+if ($data['exceeded_limit']) {
 	$table->setFooter([
 		(new CCol(_('Not all results are displayed. Please provide more specific search criteria.')))
 			->setColSpan($table->getNumCols())
diff --git a/ui/app/partials/trigoverview.table.top.php b/ui/app/partials/trigoverview.table.top.php
index ea73cce647a..2770baac3cb 100644
--- a/ui/app/partials/trigoverview.table.top.php
+++ b/ui/app/partials/trigoverview.table.top.php
@@ -56,7 +56,7 @@ foreach ($data['triggers_by_name'] as $trigname => $host_to_trig) {
 	$table->addRow($row);
 }
 
-if ($data['exceeded_hosts'] || $data['exceeded_trigs']) {
+if ($data['exceeded_limit']) {
 	$table->setFooter([
 		(new CCol(_('Not all results are displayed. Please provide more specific search criteria.')))
 			->setColSpan($table->getNumCols())
diff --git a/ui/include/classes/screens/CScreenDataOverview.php b/ui/include/classes/screens/CScreenDataOverview.php
index 9e8b6ea3594..6fcb82e72e7 100644
--- a/ui/include/classes/screens/CScreenDataOverview.php
+++ b/ui/include/classes/screens/CScreenDataOverview.php
@@ -40,35 +40,15 @@ class CScreenDataOverview extends CScreenBase {
 				->addItem([_('Group'), ':', SPACE, $groups[0]['name']])
 		]))->addClass(ZBX_STYLE_DASHBRD_WIDGET_HEAD);
 
-		$data = [];
-		if ($this->screenitem['style'] == STYLE_TOP) {
-			list($db_items, $db_hosts, $items_by_name, $has_hidden_data) = getDataOverviewTop((array) $groupid, null,
-				$this->screenitem['application']
-			);
-
-			$data['visible_items'] = getDataOverviewCellData($db_hosts, $db_items, $items_by_name,
-				ZBX_PROBLEM_SUPPRESSED_FALSE
-			);
-			$data['db_hosts'] = $db_hosts;
-			$data['items_by_name'] = $items_by_name;
-			$data['has_hidden_data'] = $has_hidden_data;
-
-			$table = new CPartial('dataoverview.table.top', $data);
-		}
-		else {
-			list($db_items, $db_hosts, $items_by_name, $has_hidden_data) = getDataOverviewLeft((array) $groupid, null,
-				$this->screenitem['application']
-			);
-
-			$data['visible_items'] = getDataOverviewCellData($db_hosts, $db_items, $items_by_name,
-				ZBX_PROBLEM_SUPPRESSED_FALSE
-			);
-			$data['db_hosts'] = $db_hosts;
-			$data['items_by_name'] = $items_by_name;
-			$data['has_hidden_data'] = $has_hidden_data;
-
-			$table = new CPartial('dataoverview.table.left', $data);
-		}
+		$data = array_combine(['items', 'hosts', 'has_hidden_data'],
+			getDataOverview((array) $groupid, null, [
+				'application' => $this->screenitem['application'],
+				'show_suppressed' => ZBX_PROBLEM_SUPPRESSED_FALSE
+			])
+		);
+
+		$partial = ($this->screenitem['style'] == STYLE_TOP) ? 'dataoverview.table.top' : 'dataoverview.table.left';
+		$table = new CPartial($partial, $data);
 
 		$footer = (new CList())
 			->addItem(_s('Updated: %1$s', zbx_date2str(TIME_FORMAT_SECONDS)))
diff --git a/ui/include/classes/screens/CScreenTriggersOverview.php b/ui/include/classes/screens/CScreenTriggersOverview.php
index 8a438f0f590..b4fdf419279 100644
--- a/ui/include/classes/screens/CScreenTriggersOverview.php
+++ b/ui/include/classes/screens/CScreenTriggersOverview.php
@@ -38,9 +38,9 @@ class CScreenTriggersOverview extends CScreenBase {
 		]))->addClass(ZBX_STYLE_DASHBRD_WIDGET_HEAD);
 
 		$data = [];
-		list($data['db_hosts'], $data['db_triggers'], $data['dependencies'], $data['triggers_by_name'],
-			$data['hosts_by_name'], $data['exceeded_hosts'], $data['exceeded_trigs']
-		) = getTriggersOverviewData((array) $this->screenitem['resourceid'], $this->screenitem['application']);
+		[$data['db_hosts'], $data['db_triggers'], $data['dependencies'], $data['triggers_by_name'],
+			$data['hosts_by_name'], $data['exceeded_limit']
+		] = getTriggersOverviewData((array) $this->screenitem['resourceid'], $this->screenitem['application']);
 
 		if ($this->screenitem['style'] == STYLE_TOP) {
 			$table = new CPartial('trigoverview.table.top', $data);
diff --git a/ui/include/items.inc.php b/ui/include/items.inc.php
index 61fc193cfcd..13176484db6 100644
--- a/ui/include/items.inc.php
+++ b/ui/include/items.inc.php
@@ -1001,32 +1001,27 @@ function makeItemTemplatesHtml($itemid, array $parent_templates, $flag, bool $pr
 }
 
 /**
- * @param array $db_hosts
+ * Collect latest value and actual severity value for each item of Data overview table.
+ *
  * @param array $db_items
- * @param array $items_by_name
+ * @param array $data
  * @param int   $show_suppressed
  *
  * @return array
  */
-function getDataOverviewCellData(array &$db_hosts, array &$db_items, array &$items_by_name, int $show_suppressed): array {
-	$visible_items = [];
-	foreach ($items_by_name as $hostid_to_itemids) {
-		foreach ($hostid_to_itemids as $itemid) {
-			$visible_items[$itemid] = $db_items[$itemid];
-		}
-	}
-
-	$history = Manager::History()->getLastValues($visible_items, 1,
+function getDataOverviewCellData(array $db_items, array $data, int $show_suppressed): array {
+	$history = Manager::History()->getLastValues($db_items, 1,
 		timeUnitToSeconds(CSettingsHelper::get(CSettingsHelper::HISTORY_PERIOD))
 	);
 
 	$db_triggers = getTriggersWithActualSeverity([
 		'output' => ['triggerid', 'priority', 'value'],
 		'selectItems' => ['itemid'],
-		'itemids' => array_keys($visible_items),
+		'itemids' => array_keys($db_items),
 		'monitored' => true,
 		'preservekeys' => true
 	], ['show_suppressed' => $show_suppressed]);
+
 	$itemid_to_triggerids = [];
 	foreach ($db_triggers as $triggerid => $db_trigger) {
 		foreach ($db_trigger['items'] as $item) {
@@ -1037,38 +1032,41 @@ function getDataOverviewCellData(array &$db_hosts, array &$db_items, array &$ite
 		}
 	}
 
-	foreach ($items_by_name as $hostid_to_itemids) {
-		foreach ($db_hosts as $host) {
-			if (!array_key_exists($host['hostid'], $hostid_to_itemids)) {
-				continue;
-			}
+	// Apply values and trigger severity to each $data cell.
+	foreach ($data as &$data_clusters) {
+		foreach ($data_clusters as &$data_cluster) {
+			foreach ($data_cluster as &$item) {
+				$itemid = $item['itemid'];
+
+				if (array_key_exists($itemid, $itemid_to_triggerids)) {
+					$max_priority = -1;
+					$max_priority_triggerid = -1;
+					foreach ($itemid_to_triggerids[$itemid] as $triggerid) {
+						$trigger = $db_triggers[$triggerid];
 
-			$itemid = $hostid_to_itemids[$host['hostid']];
-			$visible_items[$itemid]['value'] = array_key_exists($itemid, $history)
-				? $history[$itemid][0]['value']
-				: null;
-			$trigger = null;
-
-			if (array_key_exists($itemid, $itemid_to_triggerids)) {
-				$max_priority = -1;
-				$max_priority_triggerid = -1;
-				foreach ($itemid_to_triggerids[$itemid] as $triggerid) {
-					$trigger = $db_triggers[$triggerid];
-
-					// Bump lower priority triggers of value "true" ahead of triggers with value "false".
-					$multiplier = ($trigger['value'] == TRIGGER_VALUE_TRUE) ? TRIGGER_SEVERITY_COUNT : 0;
-					if ($trigger['priority'] + $multiplier > $max_priority) {
-						$max_priority_triggerid = $triggerid;
-						$max_priority = $trigger['priority'] + $multiplier;
+						// Bump lower priority triggers of value "true" ahead of triggers with value "false".
+						$multiplier = ($trigger['value'] == TRIGGER_VALUE_TRUE) ? TRIGGER_SEVERITY_COUNT : 0;
+						if ($trigger['priority'] + $multiplier > $max_priority) {
+							$max_priority_triggerid = $triggerid;
+							$max_priority = $trigger['priority'] + $multiplier;
+						}
 					}
+					$trigger = $db_triggers[$max_priority_triggerid];
 				}
-				$trigger = $db_triggers[$max_priority_triggerid];
+				else {
+					$trigger = null;
+				}
+
+				$item += [
+					'value' => array_key_exists($itemid, $history) ? $history[$itemid][0]['value'] : null,
+					'trigger' => $trigger
+				];
 			}
-			$visible_items[$itemid]['trigger'] = $trigger;
 		}
 	}
+	unset($data_clusters, $data_cluster, $item);
 
-	return $visible_items;
+	return $data;
 }
 
 /**
@@ -1079,33 +1077,54 @@ function getDataOverviewCellData(array &$db_hosts, array &$db_items, array &$ite
  * @return array
  */
 function getDataOverviewItems(?array $groupids = null, ?array $hostids = null, ?string $application = ''): array {
-	$limit = CSettingsHelper::get(CSettingsHelper::SEARCH_LIMIT);
 	if ($application !== '') {
-		$applicationids = array_keys(API::Application()->get([
-			'output' => [],
+		$db_applications = API::Application()->get([
+			'output' => ['hostid'],
 			'hostids' => $hostids,
 			'groupids' => $groupids,
 			'search' => ['name' => $application],
 			'preservekeys' => true
-		]));
+		]);
+
+		$applicationids = array_keys($db_applications);
+		$hostids = array_keys(array_flip(array_column($db_applications, 'hostid')));
+	}
+	else {
+		$applicationids = null;
+	}
 
+	if ($hostids === null) {
+		$limit = (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE) + 1;
+		$db_hosts = API::Host()->get([
+			'output' => [],
+			'groupids' => $groupids,
+			'applicationids' => $applicationids,
+			'monitored_hosts' => true,
+			'with_monitored_items' => true,
+			'preservekeys' => true,
+			'limit' => $limit
+		]);
+		$hostids = array_keys($db_hosts);
+	}
+
+	if ($application !== '') {
 		$db_items = API::Item()->get([
 			'output' => ['itemid', 'hostid', 'name', 'key_', 'value_type', 'units', 'valuemapid'],
+			'selectHosts' => ['name'],
 			'applicationids' => $applicationids,
 			'monitored' => true,
 			'webitems' => true,
-			'limit' => $limit,
 			'preservekeys' => true
 		]);
 	}
 	else {
 		$db_items = API::Item()->get([
 			'output' => ['itemid', 'hostid', 'name', 'key_', 'value_type', 'units', 'valuemapid'],
+			'selectHosts' => ['name'],
 			'hostids' => $hostids,
 			'groupids' => $groupids,
 			'monitored' => true,
 			'webitems' => true,
-			'limit' => $limit,
 			'preservekeys' => true
 		]);
 	}
@@ -1117,128 +1136,101 @@ function getDataOverviewItems(?array $groupids = null, ?array $hostids = null, ?
 		['field' => 'itemid', 'order' => ZBX_SORT_UP]
 	]);
 
-	return $db_items;
+	return [$db_items, $hostids];
 }
 
 /**
- * @param array  $groupids
- * @param array  $hostids
- * @param array  $itemids
- * @param string $application
+ * @param array   $groupids
+ * @param array   $hostids
+ * @param array   $filter
+ * @param string  $filter['application']
+ * @param int     $filter['show_suppressed']
  *
  * @return array
  */
-function getDataOverviewHosts(?array $groupids, ?array $hostids, ?array $itemids, ?string $application = ''): array {
-	$limit = CSettingsHelper::get(CSettingsHelper::SEARCH_LIMIT);
-	if ($application !== '') {
-		$applicationids = array_keys(API::Application()->get([
-			'output' => [],
-			'hostids' => $hostids ? $hostids : null,
-			'groupids' => $groupids ? $groupids : null,
-			'search' => ['name' => $application],
-			'preservekeys' => true
-		]));
+function getDataOverview(?array $groupids, ?array $hostids, array $filter): array {
+	[$db_items, $hostids] = getDataOverviewItems($groupids, $hostids, $filter['application']);
 
-		$db_hosts = API::Host()->get([
-			'output' => ['name', 'hostid'],
-			'groupids' => $groupids,
-			'applicationids' => $applicationids,
-			'monitored_hosts' => true,
-			'with_monitored_items' => true,
-			'preservekeys' => true,
-			'limit' => $limit
-		]);
-	}
-	else {
-		$db_hosts = API::Host()->get([
-			'output' => ['name', 'hostid'],
-			'monitored_hosts' => true,
-			'hostids' => $hostids,
-			'itemids' => $itemids,
-			'groupids' => $groupids,
-			'with_monitored_items' => true,
-			'preservekeys' => true,
-			'limit' => $limit
-		]);
-	}
+	$data = [];
+	$item_counter = [];
+	$db_hosts = [];
 
-	CArrayHelper::sort($db_hosts, [
-		['field' => 'name', 'order' => ZBX_SORT_UP]
-	]);
+	foreach ($db_items as $db_item) {
+		$item_name = $db_item['name_expanded'];
+		$host_name = $db_item['hosts'][0]['name'];
+		$db_hosts[$db_item['hostid']] = $db_item['hosts'][0];
 
-	return $db_hosts;
-}
+		if (!array_key_exists($host_name, $item_counter)) {
+			$item_counter[$host_name] = [];
+		}
 
-/**
- * @param array  $groupids
- * @param array  $hostids
- * @param string $application
- *
- * @return array
- */
-function getDataOverviewLeft(?array $groupids, ?array $hostids, string $application = ''): array {
-	$db_items = getDataOverviewItems($groupids, $hostids, $application);
-	$items_by_name = [];
-	foreach ($db_items as $itemid => $db_item) {
-		if (!array_key_exists($db_item['name_expanded'], $items_by_name)) {
-			$items_by_name[$db_item['name_expanded']] = [];
+		if (!array_key_exists($item_name, $item_counter[$host_name])) {
+			$item_counter[$host_name][$item_name] = 0;
 		}
-		$items_by_name[$db_item['name_expanded']][$db_item['hostid']] = $itemid;
-	}
 
-	$hidden_items_cnt = count(array_splice($items_by_name, (int) CSettingsHelper::get(
-		CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE
-	)));
+		$item_place = $item_counter[$host_name][$item_name];
+		$item_counter[$host_name][$item_name]++;
 
-	$itemids = [];
-	foreach ($items_by_name as $hostid_to_itemid) {
-		foreach ($hostid_to_itemid as $itemid) {
-			$itemids[] = $itemid;
+		$item = [
+			'itemid' => $db_item['itemid'],
+			'value_type' => $db_item['value_type'],
+			'units' => $db_item['units'],
+			'valuemapid' => $db_item['valuemapid'],
+			'acknowledged' => array_key_exists('acknowledged', $db_item) ? $db_item['acknowledged'] : 0
+		];
+
+		if (array_key_exists('triggerid', $db_item)) {
+			$item += [
+				'triggerid' => $db_item['triggerid'],
+				'severity' => $db_item['priority'],
+				'tr_value' => $db_item['value']
+			];
+		}
+		else {
+			$item += [
+				'triggerid' => null,
+				'severity' => null,
+				'tr_value' => null
+			];
 		}
+
+		$data[$item_name][$item_place][$host_name] = $item;
 	}
-	$db_items = array_intersect_key($db_items, array_flip($itemids));
 
-	$db_hosts = getDataOverviewHosts(null, null, $itemids);
-	$db_hosts_ctn = count($db_hosts);
-	$db_hosts = array_slice($db_hosts, 0, (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE), true);
+	CArrayHelper::sort($db_hosts, [
+		['field' => 'name', 'order' => ZBX_SORT_UP],
+	]);
 
-	$has_hidden_data = ($hidden_items_cnt || ($db_hosts_ctn > count($db_hosts)));
+	$data_display_limit = (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE);
+	$has_hidden_hosts = (count($db_hosts) > $data_display_limit);
+	$db_hosts = array_slice($db_hosts, 0, $data_display_limit, true);
 
-	return [$db_items, $db_hosts, $items_by_name, $has_hidden_data];
-}
+	$data = array_slice($data, 0, $data_display_limit);
+	$items_left = $data_display_limit;
+	$itemids = [];
+	array_walk($data, function (array &$item_columns) use ($data_display_limit, &$itemids, &$items_left) {
+		if ($items_left != 0) {
+			$item_columns = array_slice($item_columns, 0, min($data_display_limit, $items_left));
+			$items_left -= count($item_columns);
+		}
+		else {
+			$item_columns = null;
+			return;
+		}
 
-/**
- * @param array  $groupids
- * @param array  $hostids
- * @param string $application
- *
- * @return array
- */
-function getDataOverviewTop(?array $groupids, ?array $hostids, string $application = ''): array {
-	$db_hosts = getDataOverviewHosts($groupids, $hostids, null, $application);
-	$hostids = array_keys($db_hosts);
-	$hidden_db_hosts_cnt = count(array_splice($hostids, (int) CSettingsHelper::get(
-		CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE
-	)));
-	$db_hosts = array_intersect_key($db_hosts, array_flip($hostids));
-
-	$db_items = getDataOverviewItems(null, $hostids, $application);
-	$items_by_name = [];
-	foreach ($db_items as $itemid => $db_item) {
-		if (!array_key_exists($db_item['name_expanded'], $items_by_name)) {
-			$items_by_name[$db_item['name_expanded']] = [];
-		}
-		$items_by_name[$db_item['name_expanded']][$db_item['hostid']] = $itemid;
-	}
-
-	$items_by_name_ctn = count($items_by_name);
-	$items_by_name = array_slice($items_by_name, 0,
-		(int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE), true
-	);
+		array_walk($item_columns, function (array &$item_column) use ($data_display_limit, &$itemids) {
+			$item_column = array_slice($item_column, 0, $data_display_limit);
+			$itemids += array_column($item_column, 'itemid', 'itemid');
+		});
+	});
+	$data = array_filter($data);
+
+	$has_hidden_items = (count($db_items) != count($itemids));
 
-	$has_hidden_data = ($hidden_db_hosts_cnt || ($items_by_name_ctn > count($items_by_name)));
+	$db_items = array_intersect_key($db_items, $itemids);
+	$data = getDataOverviewCellData($db_items, $data, $filter['show_suppressed']);
 
-	return [$db_items, $db_hosts, $items_by_name, $has_hidden_data];
+	return [$data, $db_hosts, ($has_hidden_items || $has_hidden_hosts)];
 }
 
 /**
diff --git a/ui/include/triggers.inc.php b/ui/include/triggers.inc.php
index a9625c269bd..9dbe4ae2fcc 100644
--- a/ui/include/triggers.inc.php
+++ b/ui/include/triggers.inc.php
@@ -676,55 +676,47 @@ function replace_template_dependencies($deps, $hostid) {
 }
 
 /**
+ * Prepare arrays containing only hosts and triggers that will be shown results table.
+ *
  * @param array $db_hosts
  * @param array $db_triggers
- * @param int   $limit
  *
  * @return array
  */
-function getTriggersOverviewTableData(array $db_hosts, array $db_triggers, int $limit): array {
+function getTriggersOverviewTableData(array $db_hosts, array $db_triggers): array {
+	// Prepare triggers to show in results table.
 	$triggers_by_name = [];
-	$hosts_by_name = [];
-	$exceeded_hosts = false;
-	$exceeded_trigs = false;
-
 	foreach ($db_triggers as $trigger) {
-		$trigger_name = $trigger['description'];
-		$triggerid = $trigger['triggerid'];
-
-		CArrayHelper::sort($trigger['hosts'], ['name']);
-
 		foreach ($trigger['hosts'] as $host) {
-			$host_name = $host['name'];
-			$hostid = $host['hostid'];
-
-			if (!array_key_exists($hostid, $db_hosts)) {
+			if (!array_key_exists($host['hostid'], $db_hosts)) {
 				continue;
 			}
 
-			if (!array_key_exists($trigger_name, $triggers_by_name)) {
-				$triggers_by_name[$trigger_name] = [];
-			}
-
-			if (!array_key_exists($host_name, $hosts_by_name)) {
-				$hosts_by_name[$host_name] = [];
-			}
-
-			$triggers_by_name[$trigger_name][$hostid] = $triggerid;
-			$hosts_by_name[$host_name] = $hostid;
+			$triggers_by_name[$trigger['description']][$host['hostid']] = $trigger['triggerid'];
+		}
+	}
 
-			$exceeded_trigs = (count($triggers_by_name) > $limit);
-			$exceeded_hosts = (count($hosts_by_name) > $limit);
+	$limit = (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE);
+	$exceeded_trigs = (count($triggers_by_name) > $limit);
+	$triggers_by_name = array_slice($triggers_by_name, 0, $limit);
+	foreach ($triggers_by_name as $name => $triggers) {
+		$triggers_by_name[$name] = array_slice($triggers, 0, $limit, true);
+	}
 
-			if ($exceeded_hosts || $exceeded_trigs) {
-				$hosts_by_name = array_slice($hosts_by_name, 0, $limit, true);
-				$triggers_by_name = array_slice($triggers_by_name, 0, $limit, true);
-				break 2;
-			}
+	// Prepare hosts to show in results table.
+	$exceeded_hosts = false;
+	$hosts_by_name = [];
+	foreach ($db_hosts as $host) {
+		if (count($hosts_by_name) >= $limit) {
+			$exceeded_hosts = true;
+			break;
+		}
+		else {
+			$hosts_by_name[$host['name']] = $host['hostid'];
 		}
 	}
 
-	return [$triggers_by_name, $hosts_by_name, $exceeded_hosts, $exceeded_trigs];
+	return [$triggers_by_name, $hosts_by_name, ($exceeded_hosts || $exceeded_trigs)];
 }
 
 /**
@@ -742,16 +734,10 @@ function getTriggersOverviewTableData(array $db_hosts, array $db_triggers, int $
 function getTriggersOverviewData(array $groupids, string $application, array $host_options = [],
 		array $trigger_options = [], array $problem_options = []): array {
 
-	$exhausted_hosts = false;
-	$exhausted_triggers = false;
-	$exceeded_hosts = false;
-	$exceeded_trigs = false;
-
 	$host_options = [
 		'output' => ['hostid', 'name'],
 		'groupids' => $groupids ? $groupids : null,
-		'sortfield' => 'name',
-		'sortorder' => ZBX_SORT_UP,
+		'with_monitored_triggers' => true,
 		'preservekeys' => true
 	] + $host_options;
 
@@ -761,78 +747,65 @@ function getTriggersOverviewData(array $groupids, string $application, array $ho
 		],
 		'selectHosts' => ['hostid', 'name'],
 		'selectDependencies' => ['triggerid'],
-		'monitored' => true,
-		'sortfield' => 'description',
-		'sortorder' => ZBX_SORT_UP,
-		'preservekeys' => true
+		'monitored' => true
 	] + $trigger_options;
 
 	$problem_options += [
-		'min_severity' => TRIGGER_SEVERITY_NOT_CLASSIFIED,
-		'show_suppressed' => ZBX_PROBLEM_SUPPRESSED_FALSE,
-		'time_from' => null
+		'show_suppressed' => ZBX_PROBLEM_SUPPRESSED_FALSE
 	];
 
-	$db_triggers = [];
-	$db_hosts = [];
-	$applicationids = [];
-	$dependencies = [];
-
-	$triggers_by_name = [];
-	$hosts_by_name = [];
-
 	$limit = (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE);
-	$axis_limit = (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE);
 
 	do {
-		if (!$exhausted_hosts) {
-			$db_hosts = API::Host()->get(['limit' => $limit + 1] + $host_options);
-			$exhausted_hosts = (count($db_hosts) < $limit);
-
-			if ($application !== '') {
-				$applications = API::Application()->get([
-					'output' => [],
-					'hostids' => array_keys($db_hosts),
-					'search' => ['name' => $application],
-					'preservekeys' => true
-				]);
-				$applicationids = array_keys($applications);
-			}
-		}
+		$db_hosts = API::Host()->get(['limit' => $limit + 1] + $host_options);
+		$fetch_hosts = (count($db_hosts) > $limit);
 
-		if (!$exhausted_triggers) {
-			$db_triggers = getTriggersWithActualSeverity([
-				'applicationids' => ($application !== '') ? $applicationids : null,
+		$applicationids = ($application !== '')
+			? array_keys(API::Application()->get([
+				'output' => [],
 				'hostids' => array_keys($db_hosts),
-				'limit' => $limit + 1
-			]+ $trigger_options, $problem_options);
+				'search' => ['name' => $application],
+				'preservekeys' => true
+			]))
+			: null;
 
-			$db_triggers = CMacrosResolverHelper::resolveTriggerNames($db_triggers, true);
+		$db_triggers = getTriggersWithActualSeverity([
+			'applicationids' => $applicationids,
+			'hostids' => array_keys($db_hosts)
+		] + $trigger_options, $problem_options);
 
-			if ($db_triggers) {
-				$dependencies = getTriggerDependencies($db_triggers);
-			}
+		if (!$db_triggers) {
+			$db_hosts = [];
+		}
 
-			$exhausted_triggers = (count($db_triggers) < $limit);
+		// Unset hosts without having matching triggers.
+		$represented_hosts = [];
+		foreach ($db_triggers as $trigger) {
+			$hostids = array_column($trigger['hosts'], 'hostid');
+			$represented_hosts += array_combine($hostids, $hostids);
 		}
 
-		CArrayHelper::sort($db_triggers, ['description']);
+		$db_hosts = array_intersect_key($db_hosts, $represented_hosts);
 
-		list($triggers_by_name, $hosts_by_name, $exceeded_hosts, $exceeded_trigs) = getTriggersOverviewTableData(
-			$db_hosts, $db_triggers, $axis_limit
-		);
+		$fetch_hosts &= (count($db_hosts) < $limit);
+		$limit += (int) CSettingsHelper::get(CSettingsHelper::MAX_OVERVIEW_TABLE_SIZE);
 
-		if ($exceeded_hosts || $exceeded_trigs) {
-			break;
-		}
+	} while ($fetch_hosts);
 
-		$limit += $limit;
-	} while (!($exhausted_triggers && $exhausted_hosts));
+	CArrayHelper::sort($db_hosts, [
+		['field' => 'name', 'order' => ZBX_SORT_UP]
+	]);
 
-	CArrayHelper::sort($db_hosts, ['name']);
+	$db_triggers = CMacrosResolverHelper::resolveTriggerNames($db_triggers, true);
+	$dependencies = $db_triggers ? getTriggerDependencies($db_triggers) : [];
 
-	return [$db_hosts, $db_triggers, $dependencies, $triggers_by_name, $hosts_by_name, $exceeded_hosts, $exceeded_trigs
-	];
+	CArrayHelper::sort($db_triggers, [
+		['field' => 'description', 'order' => ZBX_SORT_UP]
+	]);
+
+	[$triggers_by_name, $hosts_by_name, $exceeded_limit] = getTriggersOverviewTableData($db_hosts, $db_triggers);
+
+	return [$db_hosts, $db_triggers, $dependencies, $triggers_by_name, $hosts_by_name, $exceeded_limit];
 }
 
 /**
@@ -963,8 +936,8 @@ function getTriggersWithActualSeverity(array $trigger_options, array $problem_op
 /**
  * Creates and returns a trigger status cell for the trigger overview table.
  *
- * @param array $trigger
- * @param array $dependencies  The list of trigger dependencies, prepared by getTriggerDependencies() function.
+ * @param array  $trigger
+ * @param array  $dependencies  The list of trigger dependencies, prepared by getTriggerDependencies() function.
  *
  * @return CCol
  */
diff --git a/ui/include/views/monitoring.overview.items.php b/ui/include/views/monitoring.overview.items.php
index a5409e68dd0..57233418f43 100644
--- a/ui/include/views/monitoring.overview.items.php
+++ b/ui/include/views/monitoring.overview.items.php
@@ -156,22 +156,12 @@ if ($web_layout_mode == ZBX_LAYOUT_NORMAL) {
 	);
 }
 
-if ($data['view_style'] == STYLE_TOP) {
-	$table = new CPartial('dataoverview.table.top', [
-		'visible_items' => $data['visible_items'],
-		'db_hosts' => $data['db_hosts'],
-		'items_by_name' => $data['items_by_name'],
-		'has_hidden_data' => $data['has_hidden_data']
-	]);
-}
-else {
-	$table = new CPartial('dataoverview.table.left', [
-		'visible_items' => $data['visible_items'],
-		'db_hosts' => $data['db_hosts'],
-		'items_by_name' => $data['items_by_name'],
-		'has_hidden_data' => $data['has_hidden_data']
-	]);
-}
+$partial = ($data['view_style'] == STYLE_TOP) ? 'dataoverview.table.top' : 'dataoverview.table.left';
+$table = new CPartial($partial, [
+	'items' => $data['items'],
+	'hosts' => $data['hosts'],
+	'has_hidden_data' => $data['has_hidden_data']
+]);
 
 $widget->addItem($table);
 
diff --git a/ui/overview.php b/ui/overview.php
index 8526a8ff299..0c20441345d 100644
--- a/ui/overview.php
+++ b/ui/overview.php
@@ -134,8 +134,7 @@ $data = [
 	'dependencies' => [],
 	'triggers_by_name' => [],
 	'hosts_by_name' => [],
-	'exceeded_hosts' => false,
-	'exceeded_trigs' => false
+	'exceeded_limit' => false
 ];
 
 // fetch trigger data
@@ -219,9 +218,9 @@ if ($type == SHOW_TRIGGERS) {
 		'close' => CWebUser::checkAccess(CRoleHelper::ACTIONS_CLOSE_PROBLEMS)
 	];
 
-	list($data['db_hosts'], $data['db_triggers'], $data['dependencies'], $data['triggers_by_name'],
-		$data['hosts_by_name'], $data['exceeded_hosts'], $data['exceeded_trigs']
-	) = getTriggersOverviewData($groupids, $filter['application'], $host_options, $trigger_options, $problem_options);
+	[$data['db_hosts'], $data['db_triggers'], $data['dependencies'], $data['triggers_by_name'], $data['hosts_by_name'],
+		$data['exceeded_limit']
+	] = getTriggersOverviewData($groupids, $filter['application'], $host_options, $trigger_options, $problem_options);
 
 	$data['filter'] = $filter;
 
@@ -262,23 +261,7 @@ else {
 	$groupids = $data['filter']['groups'] ? getSubGroups(array_keys($data['filter']['groups'])) : null;
 	$hostids = $data['filter']['hosts'] ? array_keys($data['filter']['hosts']) : null;
 
-	if ($data['view_style'] == STYLE_TOP) {
-		list($db_items, $db_hosts, $items_by_name, $has_hidden_data) = getDataOverviewTop($groupids, $hostids,
-			$data['filter']['application']
-		);
-	}
-	else {
-		list($db_items, $db_hosts, $items_by_name, $has_hidden_data) = getDataOverviewLeft($groupids, $hostids,
-			$data['filter']['application']
-		);
-	}
-
-	$data['visible_items'] = getDataOverviewCellData($db_hosts, $db_items, $items_by_name,
-		$data['filter']['show_suppressed']
-	);
-	$data['db_hosts'] = $db_hosts;
-	$data['items_by_name'] = $items_by_name;
-	$data['has_hidden_data'] = $has_hidden_data;
+	[$data['items'], $data['hosts'], $data['has_hidden_data']] = getDataOverview($groupids, $hostids, $data['filter']);
 
 	// Render view.
 	echo (new CView('monitoring.overview.items', $data))->getOutput();