Removing SQL_CALC_FOUND_ROWS

.changelogs/remove_sql-calc-found-rows.yml

@@ -0,0 +1,4 @@
+significance: major
+type: changed
+entry: Removing use of SQL_CALC_FOUND_ROWS due to depreciation in MySQL and
+  observed unreliability of count results.

composer.json

@@ -32,7 +32,7 @@
     "lifterlms/lifterlms-blocks": "2.7.2",
     "lifterlms/lifterlms-cli": "0.0.5",
     "lifterlms/lifterlms-helper": "3.5.9",
-    "lifterlms/lifterlms-rest": "1.0.4",
+    "lifterlms/lifterlms-rest": "1.0.5",
     "woocommerce/action-scheduler": "3.5.4",
     "gocodebox/banner-notifications": "1.1.1"
   },

includes/abstracts/abstract.llms.database.query.php

@@ -26,6 +26,18 @@ abstract class LLMS_Database_Query extends LLMS_Abstract_Query {
 	 */
 	protected $id = 'database';
 
+	/**
+	 * SQL query used to count total found results.
+	 *
+	 * Set by subclasses in prepare_query() from the same clause
+	 * variables (FROM, JOIN, WHERE) used for the main query.
+	 *
+	 * @since [version]
+	 *
+	 * @var string
+	 */
+	protected $count_query = '';
+
 	/**
 	 * Retrieve query argument default values.
 	 *
@@ -152,32 +164,38 @@ protected function set_found_results() {
 	}
 
 	/**
-	 * Perform a SQL to retrieve the total number of found results for the given query.
+	 * Retrieve the total number of found results for the given query.
+	 *
+	 * Uses a separate COUNT(*) query built from the same SQL clauses as the
+	 * main query, set by subclasses in prepare_query().
 	 *
 	 * @since 6.0.0
+	 * @since [version] Replaced FOUND_ROWS() with $this->count_query.
 	 *
 	 * @return int
 	 */
 	protected function found_results() {
 
 		global $wpdb;
-		return (int) $wpdb->get_var( 'SELECT FOUND_ROWS()' ); // db call ok; no-cache ok.
+
+		if ( empty( $this->count_query ) ) {
+			return 0;
+		}
+
+		return (int) $wpdb->get_var( $this->count_query ); // db call ok; no-cache ok.
 	}
 
 	/**
 	 * Retrieve the prepared SQL for the SELECT clause.
 	 *
 	 * @since 4.5.1
+	 * @since [version] Removed SQL_CALC_FOUND_ROWS; found results are now counted via a separate query.
 	 *
 	 * @param string $select_columns Optional. Columns to select. Default '*'.
 	 * @return string
 	 */
 	protected function sql_select_columns( $select_columns = '*' ) {
 
-		if ( ! $this->get( 'count_only' ) && ! $this->get( 'no_found_rows' ) ) {
-			$select_columns = 'SQL_CALC_FOUND_ROWS ' . $select_columns;
-		}
-
 		if ( $this->get( 'suppress_filters' ) ) {
 			return $select_columns;
 		}
@@ -200,11 +218,16 @@ protected function sql_select_columns( $select_columns = '*' ) {
 	 *
 	 * @since 3.16.0
 	 * @since 4.5.1 Drop use of `$this->get_filter('limit')` in favor of `"llms_{$this->id}_query_limit"`.
+	 * @since [version] Returns empty string for count_only queries.
 	 *
 	 * @return string
 	 */
 	protected function sql_limit() {
 
+		if ( $this->get( 'count_only' ) ) {
+			return '';
+		}
+
 		global $wpdb;
 
 		$sql = $wpdb->prepare( 'LIMIT %d, %d', $this->get_skip(), $this->get( 'per_page' ) );
@@ -270,6 +293,58 @@ protected function sql_orderby() {
 		return apply_filters( "llms_{$this->id}_query_orderby", $sql, $this );
 	}
 
+	/**
+	 * Execute a query.
+	 *
+	 * Overrides the parent to detect if a filter re-added SQL_CALC_FOUND_ROWS
+	 * to the query, and falls back to FOUND_ROWS() if so.
+	 *
+	 * Also warns when a subclass does not set $this->count_query, which means
+	 * get_found_results() and get_max_pages() will return 0.
+	 *
+	 * @since [version]
+	 *
+	 * @return void
+	 */
+	public function query() {
+
+		parent::query();
+
+		$has_sql_calc = ! $this->get( 'suppress_filters' ) &&
+			is_string( $this->query ) &&
+			str_contains( $this->query, 'SQL_CALC_FOUND_ROWS' );
+
+		if ( $has_sql_calc ) {
+			_deprecated_argument(
+				"llms_{$this->id}_query_prepare_query",
+				'[version]',
+				'SQL_CALC_FOUND_ROWS should no longer be added via filters. Results are now counted with a separate COUNT query.'
+			);
+
+			global $wpdb;
+			$this->found_results = (int) $wpdb->get_var( 'SELECT FOUND_ROWS()' ); // db call ok; no-cache ok.
+			$this->max_pages     = absint( ceil( $this->found_results / $this->get( 'per_page' ) ) );
+		}
+
+		if (
+			$this->number_results &&
+			! $this->get( 'no_found_rows' ) &&
+			! $this->get( 'count_only' ) &&
+			empty( $this->count_query ) &&
+			! $has_sql_calc
+		) {
+			_doing_it_wrong(
+				get_class( $this ) . '::prepare_query',
+				sprintf(
+					/* translators: %s: The query subclass name. */
+					'Subclasses of LLMS_Database_Query should set $this->count_query in prepare_query() when no_found_rows is not true. %s does not set count_query, so get_found_results() and get_max_pages() will return 0.',
+					get_class( $this )
+				),
+				'[version]'
+			);
+		}
+	}
+
 	/**
 	 * Gets information about properties that used to be public and have been replaced with public getters.
 	 *

includes/abstracts/llms.abstract.post.data.php

@@ -248,7 +248,8 @@ public function recent_events( $args = array() ) {
 			)
 		);
 
-		$query_args['post_id'] = $this->post_id;
+		$query_args['post_id']        = $this->post_id;
+		$query_args['no_found_rows'] = true;
 
 		$query = new LLMS_Query_User_Postmeta( $query_args );
 

includes/admin/reporting/tables/llms.table.quiz.non.attempts.php

@@ -252,18 +252,7 @@ public function get_results( $args = array() ) {
 
 		$offset = ( $this->current_page - 1 ) * $per;
 
-		$results = $wpdb->get_results(
-			$wpdb->prepare(
-				"SELECT SQL_CALC_FOUND_ROWS DISTINCT
-					u.ID as user_id,
-					u.user_email,
-					u.display_name,
-					u.user_registered,
-					m_first.meta_value as first_name,
-					m_last.meta_value as last_name,
-					upm.meta_value as enrollment_status,
-					upm.updated_date as enrollment_date
-				FROM {$wpdb->users} u
+		$from_joins_where = "FROM {$wpdb->users} u
 				INNER JOIN {$wpdb->prefix}lifterlms_user_postmeta upm
 					ON u.ID = upm.user_id
 					AND upm.post_id = %d
@@ -286,19 +275,39 @@ public function get_results( $args = array() ) {
 					AND upm2.meta_key = '_status'
 				)
 				AND qa.id IS NULL
-				{$search_sql}
+				{$search_sql}";
+
+		$prepare_args = array(
+			$course->get( 'id' ),
+			$this->quiz_id,
+			$course->get( 'id' ),
+		);
+
+		$total_results = $wpdb->get_var(
+			$wpdb->prepare(
+				"SELECT COUNT(DISTINCT u.ID) {$from_joins_where}",
+				$prepare_args
+			)
+		); // db call ok; no-cache ok.
+
+		$results = $wpdb->get_results(
+			$wpdb->prepare(
+				"SELECT DISTINCT
+					u.ID as user_id,
+					u.user_email,
+					u.display_name,
+					u.user_registered,
+					m_first.meta_value as first_name,
+					m_last.meta_value as last_name,
+					upm.meta_value as enrollment_status,
+					upm.updated_date as enrollment_date
+				{$from_joins_where}
 				{$order_sql}
 				LIMIT %d, %d",
-				$course->get( 'id' ),    // Course ID for enrollment check
-				$this->quiz_id,          // Quiz ID for attempt check
-				$course->get( 'id' ),    // Course ID for latest enrollment status
-				$offset,
-				$per
+				array_merge( $prepare_args, array( $offset, $per ) )
 			)
 		);
 
-		$total_results = $wpdb->get_var( 'SELECT FOUND_ROWS()' );
-
 		$this->max_pages    = ceil( $total_results / $per );
 		$this->is_last_page = ( $this->current_page >= $this->max_pages );
 

includes/admin/reporting/tables/llms.table.quizzes.php

@@ -163,8 +163,8 @@ protected function get_data( $key, $data ) {
 			case 'attempts':
 				$query = new LLMS_Query_Quiz_Attempt(
 					array(
-						'quiz_id'  => $quiz->get( 'id' ),
-						'per_page' => 1,
+						'quiz_id'    => $quiz->get( 'id' ),
+						'count_only' => true,
 					)
 				);
 
@@ -175,7 +175,7 @@ protected function get_data( $key, $data ) {
 						'quiz_id' => $quiz->get( 'id' ),
 					)
 				);
-				$value = '<a href="' . $url . '">' . $query->get_found_results() . '</a>';
+				$value = '<a href="' . $url . '">' . $query->get_count_only_result() . '</a>';
 
 				break;
 

includes/admin/tools/class-llms-admin-tool-recurring-payment-rescheduler.php

@@ -140,16 +140,15 @@ protected function handle() {
 	 *
 	 * @since 4.6.0
 	 * @since 4.7.0 Added `SQL_CALC_FOUND_ROWS` and improved query to exclude results with a completed payment plan.
+	 * @since [version] Replaced SQL_CALC_FOUND_ROWS with a separate COUNT(*) query.
 	 *
 	 * @return object[]
 	 */
 	protected function query_orders() {
 
 		global $wpdb;
 
-		$orders = $wpdb->get_results(
-			"SELECT SQL_CALC_FOUND_ROWS p.ID
-			   FROM {$wpdb->posts} AS p
+		$from_joins_where = "FROM {$wpdb->posts} AS p
 		  LEFT JOIN {$wpdb->postmeta} AS m
 			     ON p.ID = m.post_ID
 			    AND m.meta_key = '_llms_plan_ended'
@@ -161,14 +160,19 @@ protected function query_orders() {
 			    AND p.post_type   = 'llms_order'
 			    AND p.post_status = 'llms-active'
 			    AND a.action_id IS NULL
-			    AND m.meta_value IS NULL
+			    AND m.meta_value IS NULL";
+
+		$total = $wpdb->get_var( "SELECT COUNT(*) {$from_joins_where}" ); // no-cache ok.
+		wp_cache_set( sprintf( '%s-total-results', $this->id ), $total, 'llms_tool_data' );
+
+		$orders = $wpdb->get_results(
+			"SELECT p.ID
+			   {$from_joins_where}
 		   ORDER BY p.ID ASC
 			  LIMIT 50
 			;"
 		); // no-cache ok -- Caching implemented in `get_orders()`.
 
-		wp_cache_set( sprintf( '%s-total-results', $this->id ), $wpdb->get_var( 'SELECT FOUND_ROWS()' ), 'llms_tool_data' );
-
 		return $orders;
 
 	}

includes/class-llms-events-query.php

@@ -137,16 +137,24 @@ protected function parse_args() {
 	 * @since 3.36.0
 	 * @since 4.7.0 Use `$this->sql_select_columns({columns})` to determine the columns to select.
 	 * @since 6.0.0 Renamed from `preprare_query()`.
+	 * @since [version] Build count_query from shared clauses instead of using SQL_CALC_FOUND_ROWS.
 	 *
 	 * @return string
 	 */
 	protected function prepare_query() {
 
 		global $wpdb;
 
+		$from  = "FROM {$wpdb->prefix}lifterlms_events";
+		$where = $this->sql_where();
+
+		if ( ! $this->get( 'no_found_rows' ) ) {
+			$this->count_query = "SELECT COUNT(*) {$from} {$where}";
+		}
+
 		return "SELECT {$this->sql_select_columns( 'id' )}
-				FROM {$wpdb->prefix}lifterlms_events
-				{$this->sql_where()}
+				{$from}
+				{$where}
 				{$this->sql_orderby()}
 				{$this->sql_limit()};";
 

includes/class-llms-sessions.php

@@ -348,6 +348,7 @@ public function get_session_events( $start, $args = array() ) {
 			$args['exclude'][]   = $end->get( 'id' );
 		}
 
+		$args['no_found_rows'] = true;
 		$query = new LLMS_Events_Query( $args );
 		return $query->get_events();
 

includes/class.llms.query.quiz.attempt.php

@@ -137,18 +137,27 @@ protected function parse_args() {
 	 *
 	 * @since 3.16.0
 	 * @since 6.0.0 Renamed from `preprare_query()`.
+	 * @since [version] Build count_query from shared clauses instead of using SQL_CALC_FOUND_ROWS.
 	 *
 	 * @return string
 	 */
 	protected function prepare_query() {
 
 		global $wpdb;
 
-		$select = 'SELECT SQL_CALC_FOUND_ROWS qa.id';
-		$from   = "FROM {$wpdb->prefix}lifterlms_quiz_attempts qa";
-		$joins  = $this->sql_joins();
+		$from  = "FROM {$wpdb->prefix}lifterlms_quiz_attempts qa";
+		$joins = $this->sql_joins();
+		$where = $this->sql_where();
 
-		return "{$select} {$from} {$joins} {$this->sql_where()} {$this->sql_orderby()} {$this->sql_limit()};";
+		if ( $this->get( 'count_only' ) ) {
+			return "SELECT COUNT(*) AS total {$from} {$joins} {$where};";
+		}
+
+		if ( ! $this->get( 'no_found_rows' ) ) {
+			$this->count_query = "SELECT COUNT(*) {$from} {$joins} {$where}";
+		}
+
+		return "SELECT qa.id {$from} {$joins} {$where} {$this->sql_orderby()} {$this->sql_limit()};";
 	}
 
 	/**