From a37254a976502a342a863ece8b285b96faff9494 Mon Sep 17 00:00:00 2001
From: mattab <matthieu.aubry@gmail.com>
Date: Sat, 6 Dec 2014 01:53:27 +1300
Subject: [PATCH] The ultimate prize and final step to close the issue: do not
group by the whole set of matched rows, way too slow on huge datasets!
---
core/DataAccess/LogQueryBuilder.php | 10 +++++++---
plugins/Live/tests/System/ModelTest.php | 1 -
tests/PHPUnit/Integration/SegmentTest.php | 3 +--
3 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/core/DataAccess/LogQueryBuilder.php b/core/DataAccess/LogQueryBuilder.php
index ac55ccf454..a5b2fcf986 100644
--- a/core/DataAccess/LogQueryBuilder.php
+++ b/core/DataAccess/LogQueryBuilder.php
@@ -184,14 +184,18 @@ class LogQueryBuilder
$innerSelect = implode(", \n", $neededFields);
$innerFrom = $from;
$innerWhere = $where;
- $innerGroupBy = "log_visit.idvisit";
- $innerLimit = $limit;
+ $innerLimit = $limit;
+ $innerGroupBy = "log_visit.idvisit";
$innerOrderBy = "NULL";
- // Only when there is a LIMIT then we can apply to the inner query the same ORDER BY as the parent query
if($innerLimit && $orderBy) {
+ // only When LIMITing we can apply to the inner query the same ORDER BY as the parent query
$innerOrderBy = $orderBy;
}
+ if($innerLimit) {
+ // When LIMITing, no need to GROUP BY (GROUPing by is done before the LIMIT which is super slow when large amount of rows is matched)
+ $innerGroupBy = false;
+ }
$innerQuery = $this->buildSelectQuery($innerSelect, $innerFrom, $innerWhere, $innerGroupBy, $innerOrderBy, $innerLimit);
diff --git a/plugins/Live/tests/System/ModelTest.php b/plugins/Live/tests/System/ModelTest.php
index 90196e7309..268a7861d4 100644
--- a/plugins/Live/tests/System/ModelTest.php
+++ b/plugins/Live/tests/System/ModelTest.php
@@ -91,7 +91,6 @@ class ModelTest extends SystemTestCase
AND log_visit.visit_last_action_time >= ?
AND log_visit.visit_last_action_time <= ? )
AND ( log_link_visit_action.custom_var_k1 = ? )
- GROUP BY log_visit.idvisit
ORDER BY idsite, visit_last_action_time DESC
LIMIT 100
) AS log_inner
diff --git a/tests/PHPUnit/Integration/SegmentTest.php b/tests/PHPUnit/Integration/SegmentTest.php
index 864420a161..19108b1312 100644
--- a/tests/PHPUnit/Integration/SegmentTest.php
+++ b/tests/PHPUnit/Integration/SegmentTest.php
@@ -458,7 +458,7 @@ class SegmentTest extends IntegrationTestCase
}
- public function test_getSelectQuery_whenLimit_innerQueryShouldHaveLimit()
+ public function test_getSelectQuery_whenLimit_innerQueryShouldHaveLimitAndNoGroupBy()
{
$select = 'sum(log_visit.visit_total_time) as sum_visit_length';
$from = 'log_visit';
@@ -489,7 +489,6 @@ class SegmentTest extends IntegrationTestCase
( log_visit.idvisit = ? )
AND
( log_link_visit_action.custom_var_k1 = ? )
- GROUP BY log_visit.idvisit
ORDER BY NULL
LIMIT 33
) AS log_inner
--
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