From 470d448e64051e0b863088cc61ac63ec7e2643de Mon Sep 17 00:00:00 2001
From: Sukhendu Sekhar Guria <sukhendu.guria@rtcamp.com>
Date: Fri, 5 Jun 2026 18:14:11 +0530
Subject: [PATCH] perf(query): avoid split query for single post

---
 src/wp-includes/class-wp-query.php |  3 ++-
 tests/phpunit/tests/post/query.php | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/class-wp-query.php b/src/wp-includes/class-wp-query.php
index c9bf901ae1576..9b1c0c366e4bf 100644
--- a/src/wp-includes/class-wp-query.php
+++ b/src/wp-includes/class-wp-query.php
@@ -3365,7 +3365,8 @@ public function get_posts() {
 
 		if ( null === $this->posts ) {
 			$split_the_query = (
-				$is_unfiltered_query
+				1 !== $query_vars['posts_per_page']
+				&& $is_unfiltered_query
 				&& (
 					wp_using_ext_object_cache()
 					|| ( ! empty( $limits ) && $query_vars['posts_per_page'] < 500 )
diff --git a/tests/phpunit/tests/post/query.php b/tests/phpunit/tests/post/query.php
index dece07fbd6b7f..04e786e02468e 100644
--- a/tests/phpunit/tests/post/query.php
+++ b/tests/phpunit/tests/post/query.php
@@ -809,9 +809,39 @@ public function test_split_the_query_object_cache() {
 			)
 		);
 
+		remove_filter( 'split_the_query', array( $filter, 'filter' ) );
+
 		$this->assertSame( (bool) wp_using_ext_object_cache(), $filter->get_args()[0][0] );
 	}
 
+	/**
+	 * @ticket 57416
+	 *
+	 * @dataProvider data_split_the_query_should_be_disabled_when_posts_per_page_is_one
+	 */
+	public function test_split_the_query_should_be_disabled_when_posts_per_page_is_one( $posts_per_page, $expected ) {
+		$filter = new MockAction();
+		add_filter( 'split_the_query', array( $filter, 'filter' ) );
+
+		$q = new WP_Query(
+			array(
+				'posts_per_page' => $posts_per_page,
+				'cache_results'  => false,
+			)
+		);
+
+		remove_filter( 'split_the_query', array( $filter, 'filter' ) );
+
+		$this->assertSame( $expected, $filter->get_args()[0][0] );
+	}
+
+	public function data_split_the_query_should_be_disabled_when_posts_per_page_is_one() {
+		return array(
+			'one post'  => array( 1, false ),
+			'two posts' => array( 2, true ),
+		);
+	}
+
 	/**
 	 * @ticket 56841
 	 */