Make CountWalker use COUNT(*) when $distinct is explicitly set to fal…

…se (doctrine#11552) This change makes CountWalker use COUNT(*) instead of COUNT(tbl.id), when the user declared that their query does not need to use (SELECT) DISTINCT, which is commonly the case when there are no JOINs in the query, or when the JOINs are only *ToOne. Research showed that COUNT(*) allows databases to use index(-only) scans more eagerly from any of the indexed columns, especially when the query is using a WHERE-condition that filters on an indexed column.
d-ph · Jul 22, 2024 · 57247ed · 57247ed
1 parent 1281707
commit 57247ed
Show file tree

Hide file tree

Showing 2 changed files with 34 additions and 16 deletions.
diff --git a/src/Tools/Pagination/CountWalker.php b/src/Tools/Pagination/CountWalker.php
@@ -37,27 +37,31 @@ public function walkSelectStatement(SelectStatement $selectStatement): void
  throw new RuntimeException('Cannot count query which selects two FROM components, cannot make distinction');
  }
 
- $fromRoot = reset($from);
- $rootAlias = $fromRoot->rangeVariableDeclaration->aliasIdentificationVariable;
- $rootClass = $this->getMetadataForDqlAlias($rootAlias);
- $identifierFieldName = $rootClass->getSingleIdentifierFieldName();
+ $distinct = $this->_getQuery()->getHint(self::HINT_DISTINCT);
 
- $pathType = PathExpression::TYPE_STATE_FIELD;
- if (isset($rootClass->associationMappings[$identifierFieldName])) {
- $pathType = PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION;
- }
+ $countPathExpressionOrLiteral = '*';
+ if ($distinct) {
+ $fromRoot = reset($from);
+ $rootAlias = $fromRoot->rangeVariableDeclaration->aliasIdentificationVariable;
+ $rootClass = $this->getMetadataForDqlAlias($rootAlias);
+ $identifierFieldName = $rootClass->getSingleIdentifierFieldName();
+
+ $pathType = PathExpression::TYPE_STATE_FIELD;
+ if (isset($rootClass->associationMappings[$identifierFieldName])) {
+ $pathType = PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION;
+ }
 
- $pathExpression = new PathExpression(
- PathExpression::TYPE_STATE_FIELD | PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION,
- $rootAlias,
- $identifierFieldName,
- );
- $pathExpression->type = $pathType;
+ $countPathExpressionOrLiteral = new PathExpression(
+ PathExpression::TYPE_STATE_FIELD | PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION,
+ $rootAlias,
+ $identifierFieldName,
+ );
+ $countPathExpressionOrLiteral->type = $pathType;
+ }
 
- $distinct = $this->_getQuery()->getHint(self::HINT_DISTINCT);
  $selectStatement->selectClause->selectExpressions = [
  new SelectExpression(
- new AggregateExpression('count', $pathExpression, $distinct),
+ new AggregateExpression('count', $countPathExpressionOrLiteral, $distinct),
  null,
  ),
  ];

diff --git a/tests/Tests/ORM/Tools/Pagination/CountWalkerTest.php b/tests/Tests/ORM/Tools/Pagination/CountWalkerTest.php
@@ -27,6 +27,20 @@ public function testCountQuery(): void
  );
  }
 
+ public function testCountQueryWithoutDistinctUsesCountStar(): void
+ {
+ $query = $this->entityManager->createQuery(
+ 'SELECT p, c, a FROM Doctrine\Tests\ORM\Tools\Pagination\BlogPost p JOIN p.category c JOIN p.author a',
+ );
+ $query->setHint(Query::HINT_CUSTOM_TREE_WALKERS, [CountWalker::class]);
+ $query->setHint(CountWalker::HINT_DISTINCT, false);
+
+ self::assertEquals(
+ 'SELECT count(*) AS sclr_0 FROM BlogPost b0_ INNER JOIN Category c1_ ON b0_.category_id = c1_.id INNER JOIN Author a2_ ON b0_.author_id = a2_.id',
+ $query->getSQL(),
+ );
+ }
+
  public function testCountQueryMixedResultsWithName(): void
  {
  $query = $this->entityManager->createQuery(