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Merge pull request #8915 from creative-commoners/pulls/4.4/helping-performance-exist

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NEW DataQuery::exists now generates EXISTS SQL statements
This commit is contained in:
Robbie Averill 2020-09-01 13:09:02 -07:00 committed by GitHub
commit 1eb66e2258
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3 changed files with 45 additions and 6 deletions
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2
src/ORM/DataList.php
View File

@ -963,7 +963,7 @@ class DataList extends ViewableData implements SS_List, Filterable, Sortable, Li
*/
public function exists()
{
return $this->count() > 0;
return $this->dataQuery->exists();
}
/**

35
src/ORM/DataQuery.php
View File

@ -453,6 +453,41 @@ class DataQuery
return $this->getFinalisedQuery()->count("DISTINCT {$quotedColumn}");
}
/**
* Return whether this dataquery will have records. This will use `EXISTS` statements in SQL which are more
* performant - especially when used in combination with indexed columns (that you're filtering on)
*
* @return bool
*/
public function exists(): bool
{
// Grab a statement selecting "everything" - the engine shouldn't care what's being selected in an "EXISTS"
// statement anyway
$statement = $this->getFinalisedQuery();
// Clear limit, distinct, and order as it's not relevant for an exists query
$statement->setDistinct(false);
$statement->setOrderBy(null);
$statement->setLimit(null);
// We can remove grouping if there's no "having" that might be relying on an aggregate
// Additionally, the columns being selected no longer matter
$having = $statement->getHaving();
if (empty($having)) {
$statement->setSelect('*');
$statement->setGroupBy(null);
}
// Wrap the whole thing in an "EXISTS"
$sql = 'SELECT EXISTS(' . $statement->sql($params) . ')';
$result = DB::prepared_query($sql, $params);
$row = $result->first();
$result = reset($row);
// Checking for 't' supports PostgreSQL before silverstripe/postgresql@2.2
return $result === true || $result === 1 || $result === 't';
}
/**
* Return the maximum value of the given field in this DataList
*

14
tests/php/ORM/DataQueryTest.php
View File

@ -6,6 +6,7 @@ use SilverStripe\ORM\DataQuery;
use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\DB;
use SilverStripe\Dev\SapphireTest;
use SilverStripe\ORM\Tests\DataQueryTest\ObjectE;
use SilverStripe\Security\Member;
/**
@ -386,11 +387,7 @@ class DataQueryTest extends SapphireTest
$query = new DataQuery(DataQueryTest\ObjectC::class);
$query->sort('"SortOrder"');
$query->where(
[
'"DataQueryTest_C"."Title" = ? OR "DataQueryTest_E"."SortOrder" > ?' => [
'First', 2
]
]
['"DataQueryTest_C"."Title" = ? OR "DataQueryTest_E"."SortOrder" > ?' => ['First', 2]]
);
$result = $query->getFinalisedQuery(['Title']);
$from = $result->getFrom();
@ -466,4 +463,11 @@ class DataQueryTest extends SapphireTest
$this->assertEquals('Second', $titles[1]);
$this->assertEquals('Last', $titles[2]);
}
public function testExistsCreatesFunctionalQueries()
{
$this->assertTrue(ObjectE::get()->exists());
$this->assertFalse(ObjectE::get()->where(['"Title" = ?' => 'Foo'])->exists());
$this->assertTrue(ObjectE::get()->dataQuery()->groupby('"SortOrder"')->exists());
}
}