docs(2meet-data-optimizer): correct the 1.4.0 upgrade step for the copy index

- Replace the index only on tables listed in tmdo_post_status_columns
  (ALTER ADD idx_post_status_date_id / DROP idx_post_status_date)
- Warn that `wp tmdo post-status-sync` also adds and backfills copy
  columns on every other post group (large ALTER + UPDATE)
- Found in the 2.4 rollout (dev21: aeav_only, over ten million posts)

2meet-data-optimizer.php

@@ -3,7 +3,7 @@
  * Plugin Name:       2meet Data Optimizer
  * Plugin URI:        https://2meet.io/2meet-data-optimizer
  * Description:       通用 WordPress 反 EAV 引擎：將 postmeta / usermeta / termmeta / commentmeta 自動分流至四象限扁平表（Hot / Warm / Cold / Archive），大幅提升搜尋與篩選效能。從 wp-data-optimizer v2.16.0 提煉的純核心，整合層交給 11 個 AddOn。
- * Version:           1.3.0
+ * Version:           1.4.0
  * Requires at least: 6.0
  * Tested up to:      6.9.4
  * Requires PHP:      8.1
@@ -26,7 +26,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 }
 
 // ── Constants ──────────────────────────────────────────────────────────────
-define( 'TMDO_VERSION', '1.3.0' );
+define( 'TMDO_VERSION', '1.4.0' );
 define( 'TMDO_DB_VERSION', '2.1.0' );
 define( 'TMDO_PATH', plugin_dir_path( __FILE__ ) );
 define( 'TMDO_URL', plugin_dir_url( __FILE__ ) );

CHANGELOG.md

@@ -7,6 +7,52 @@ Versioning follows [Semantic Versioning](https://semver.org/).
 
 ---
 
+## [1.4.0] — 2026-09-28 — 百萬級 listing 的路由排序與日期查詢（hardening 2.4）
+
+**性質**：效能 + 修正。無 schema 變更；post status/date 副本的索引改為三欄（見「升級後」）。
+搭配 HivePress AddOn 0.5.0。來源：dev36 第 3 階壓測（130 萬 listing、121 萬 product、6.2 萬 vendor）。
+
+### Changed
+
+- **flat-first 排序讀 flat 的 post_id 作 tie-break**：`posts.ID` 的 tie-break（ours 與外掛追加的）
+  改讀相等的 `flat.post_id`，方向與排序一致且只出現一次；group 宣告的索引可以 adapter 的
+  entity id 欄結尾，`(欄, post_id)` 索引可直接依序讀取、不需 filesort（主查詢 850 ms → 2 ms）。
+  同值的順序改為依 ID 與排序同方向（原生為 ID DESC）；集合、總數不變，翻頁穩定。（PR-118）
+- **沒有 value 的 meta 條件以 EXISTS 路由**：clause 沒有 `value` 時（HivePress 的精選 listing
+  查詢）視同 EXISTS；只帶 `meta_key`、沒有 `meta_value` 也不以 meta_value 排序的查詢亦同；
+  沒有被 orderby 引用的排序形狀 group 直接移除。HivePress 每個搜尋頁都會跑的精選 listing
+  查詢（`orderby rand`）改走扁平表：2.26 s → 0.2 s。（PR-122）
+- **status/date copy route 在 LIMIT 停下**：只有扁平表一個 JOIN 時去掉 WordPress 的
+  `GROUP BY posts.ID`，`posts.ID` tie-break 改讀 `flat.post_id`（各自保留方向、重複合併）；副本索引改為
+  `idx_post_status_date_id (post_status, post_date, post_id)`，取代兩欄的 `idx_post_status_date`。
+  dev36 價格區間（130 萬中 23.5 萬筆符合）主查詢 1.7 s → 3 ms，頁面 2.7 s → 0.34 s。（PR-128）
+
+### Fixed
+
+- 遷移引擎（backfill、`drift-check --fix`）以 REPLACE 重建 post 列時保留 `post_status` /
+  `post_date` 副本；原本重建後為 NULL，一筆 NULL 就讓整個 group 關閉 copy route。（PR-127）
+- 遷移引擎重建 post 列後遞增路由計數版本（每次呼叫／每批一次，dry run 不遞增），
+  修正後的 found rows 不再沿用舊的快取計數。（PR-129）
+
+### Dev
+
+- live 測試工具（`mut.php`、`qbench.php`）不再清空物件快取（Redis Object Cache 以伺服器端腳本
+  掃描，會卡住共用 Redis 5–20 s）。（PR-123）
+
+### 升級後
+
+- 只需替換索引：對 `tmdo_post_status_columns` 列出的每個 group 表執行
+  `ALTER TABLE <表> ADD INDEX idx_post_status_date_id (post_status, post_date, post_id), DROP INDEX idx_post_status_date`
+  （空表瞬間完成，dev36 130 萬列約 5 s）。未替換前 copy route 照常運作，只是維持 1.3.0 的速度。
+- **不要為了換索引執行 `wp tmdo post-status-sync`**：它除了替換索引，還會替**所有**尚未有副本的
+  post group 加上 `post_status` / `post_date` 欄位並逐列回填（大表 ALTER + 全表 UPDATE；dev36
+  130 萬列約 75 s，上千萬列的站更久）。只有要讓更多 group 啟用 copy route 時才執行，並先在
+  離峰時段以 `--dry-run` 確認列數。
+- 效能數字（dev36 前台，routed）：價格區間 0.34 s、價格排序 0.37 s、時薪排序 0.35 s、
+  評分排序 0.51 s、關鍵字 + 價格 0.59 s（原生 6–43 s）。
+
+---
+
 ## [1.3.0] — 2026-09-27 — 大表索引、路由計數與稽核修正（hardening 2.3）
 
 **性質**：效能 + 稽核修正。無 schema 變更（宣告的複合索引以 ALTER ADD INDEX 就地加上）。

includes/engine/class-tmdo-entity-migration-engine.php

@@ -176,6 +176,9 @@ final class TMDO_Entity_Migration_Engine {
 		// 標記完成
 		if ( ! $options['dry_run'] ) {
 			self::mark_migration_completed( $entity_type, $group_name );
+			if ( $stats['migrated'] > 0 ) {
+				self::counts_changed( $entity_type );
+			}
 		}
 
 		$stats['elapsed_sec'] = round( microtime( true ) - $start_time, 2 );
@@ -183,6 +186,19 @@ final class TMDO_Entity_Migration_Engine {
 		return $stats;
 	}
 
+	/**
+	 * Rows rebuilt outside the Hook Bus (backfill, drift-check --fix): routed
+	 * post counts cached for the old rows are stale (2.4 PR-129).
+	 *
+	 * @param string $entity_type Entity type.
+	 * @return void
+	 */
+	private static function counts_changed( string $entity_type ): void {
+		if ( 'post' === $entity_type && class_exists( 'TMDO_Post_Query_Router' ) ) {
+			TMDO_Post_Query_Router::bump_count_version();
+		}
+	}
+
 	/**
 	 * Rebuild one entity's row of a group from native meta.
 	 *
@@ -194,7 +210,7 @@ final class TMDO_Entity_Migration_Engine {
 		if ( ! $adapter || empty( $group_fields ) ) {
 			return false;
 		}
-		return self::migrate_single_entity(
+		$migrated = self::migrate_single_entity(
 			$entity_type,
 			$group_name,
 			$entity_id,
@@ -203,6 +219,10 @@ final class TMDO_Entity_Migration_Engine {
 			$adapter,
 			false
 		);
+		if ( $migrated ) {
+			self::counts_changed( $entity_type );
+		}
+		return $migrated;
 	}
 
 	/**
@@ -278,6 +298,15 @@ final class TMDO_Entity_Migration_Engine {
 			}
 		}
 
+		// REPLACE drops columns it is not given: keep a post row's status/date
+		// copies, or one NULL row turns the copy route off for the group (2.4 PR-127).
+		if ( 'post' === $entity_type && class_exists( 'TMDO_Post_Status_Sync' ) ) {
+			foreach ( TMDO_Post_Status_Sync::insert_columns( $entity_id, $group_name ) as $col => $value ) {
+				$data[ $col ] = $value;
+				$formats[]    = '%s';
+			}
+		}
+
 		if ( $dry_run ) {
 			return true;
 		}
@@ -400,6 +429,9 @@ final class TMDO_Entity_Migration_Engine {
 
 		$total = $prev_total + $batch_migrated;
 		$done  = count( $entity_ids ) < $batch_size;
+		if ( $batch_migrated > 0 ) {
+			self::counts_changed( $entity_type );
+		}
 
 		if ( $done ) {
 			self::mark_migration_completed( $entity_type, $group_name );

includes/engine/class-tmdo-entity-registry.php

@@ -159,9 +159,12 @@ final class TMDO_Entity_Registry {
 			self::$scopes[ $entity_type ][ $group_name ] = $post_types;
 		}
 		$keys = array_column( $normalized, 'key' );
+		// A sort index may end with the entity ID (flat-first tie-break, 2.4 PR-118).
+		$id_col = (string) self::$adapters[ $entity_type ]->get_entity_id_column();
 		foreach ( (array) ( $args['indexes'] ?? array() ) as $index_name => $columns ) {
 			$columns = array_values( array_map( 'strval', (array) $columns ) );
-			if ( $columns && ! array_diff( $columns, $keys ) ) {
+			$fields  = '' !== $id_col && end( $columns ) === $id_col ? array_slice( $columns, 0, -1 ) : $columns;
+			if ( $fields && ! array_diff( $fields, $keys ) ) {
 				self::$indexes[ $entity_type ][ $group_name ][ (string) $index_name ] = $columns;
 			}
 		}

includes/engine/class-tmdo-post-status-sync.php

@@ -29,7 +29,10 @@ final class TMDO_Post_Status_Sync {
 
 	public const OPTION = 'tmdo_post_status_columns';
 
-	private const INDEX = 'idx_post_status_date';
+	private const INDEX = 'idx_post_status_date_id';
+
+	/** The 2.2–2.3 (post_status, post_date) index, replaced by INDEX. */
+	private const LEGACY_INDEX = 'idx_post_status_date';
 
 	/**
 	 * Hook the sync into WordPress.
@@ -203,7 +206,12 @@ final class TMDO_Post_Status_Sync {
 			$changes[] = 'ADD COLUMN `post_date` DATETIME DEFAULT NULL';
 		}
 		if ( ! in_array( self::INDEX, $indexes, true ) ) {
-			$changes[] = 'ADD INDEX `' . self::INDEX . '` (`post_status`, `post_date`)';
+			// Ends with post_id: the router reads the date route's ID tie-break
+			// from it, so MySQL walks the index and stops at the LIMIT (2.4 PR-128).
+			$changes[] = 'ADD INDEX `' . self::INDEX . '` (`post_status`, `post_date`, `post_id`)';
+		}
+		if ( in_array( self::LEGACY_INDEX, $indexes, true ) ) {
+			$changes[] = 'DROP INDEX `' . self::LEGACY_INDEX . '`';
 		}
 		if ( $changes && false === $wpdb->query( "ALTER TABLE `{$table}` " . implode( ', ', $changes ) ) ) { // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Fixed DDL on a registry table name.
 			return false;

includes/query/class-tmdo-post-query-router.php

@@ -26,8 +26,9 @@
  * post_date copies are ready (TMDO_Post_Status_Sync) and none is missing,
  * a single-post-type search with explicit statuses and date ordering
  * INNER JOINs the table, filters the copies and orders by the copied
- * post_date, so MySQL can walk `idx_post_status_date` and stop at the
- * LIMIT. Not with NOT EXISTS: posts without a flat row must still match.
+ * post_date (ID tie-breaks read as the flat post_id), so MySQL can walk
+ * `idx_post_status_date_id` and stop at the LIMIT. Not with NOT EXISTS:
+ * posts without a flat row must still match.
  *
  * Found rows (O-4): routed searches drop SQL_CALC_FOUND_ROWS (it counts every
  * match inside the page query); found_posts_query answers from a COUNT of the
@@ -191,6 +192,25 @@ class TMDO_Post_Query_Router {
 			$routed[ $pt ][] = $route;
 			$sort            = self::sort_for( $pt, $route, $direction );
 		}
+		// meta_key alone (no meta_value, not a meta_value sort): WP_Query adds a
+		// clause that tests the key exists — HivePress's featured-listing lookup.
+		$exists_key = ! $take_key && is_string( $meta_key ) && '' !== $meta_key
+			&& '' === (string) $query->get( 'meta_value' ) && '' === (string) $query->get( 'meta_compare' )
+			&& ! in_array( $sort_name, array( 'meta_value', 'meta_value_num' ), true )
+			&& null !== self::field_for( array( 'key' => $meta_key ), $pt );
+		if ( $exists_key ) {
+			$route = self::route_clause(
+				array(
+					'key'     => $meta_key,
+					'compare' => 'EXISTS',
+				),
+				self::field_for( array( 'key' => $meta_key ), $pt )
+			);
+			if ( ! $route ) {
+				return;
+			}
+			$routed[ $pt ][] = $route;
+		}
 
 		foreach ( $raw_meta_query as $k => $clause ) {
 			if ( 'relation' === $k || ! is_array( $clause ) ) {
@@ -199,7 +219,10 @@ class TMDO_Post_Query_Router {
 			}
 			if ( ! isset( $clause['key'] ) ) {
 				// Sort shape: matches every post, only orders by the key.
-				$name  = 'AND' === $relation ? self::sort_shape( $clause ) : '';
+				$name = 'AND' === $relation ? self::sort_shape( $clause ) : '';
+				if ( '' !== $name && ! in_array( $name, $named, true ) && self::field_for( $clause[ $name ], $pt ) ) {
+					continue; // Matches every post and orders nothing here (a copy of a search's meta query).
+				}
 				$field = '' !== $name && $name === $sort_name ? self::field_for( $clause[ $name ], $pt ) : null;
 				if ( $field ) {
 					$route = self::route_clause( array( 'compare' => 'EXISTS' ) + $clause[ $name ], $field );
@@ -239,7 +262,7 @@ class TMDO_Post_Query_Router {
 		if ( empty( $routed ) && empty( $sort ) ) {
 			return;
 		}
-		if ( $take_key ) {
+		if ( $take_key || $exists_key ) {
 			$query->set( 'meta_key', '' );
 		}
 		if ( $sort ) {
@@ -678,11 +701,17 @@ class TMDO_Post_Query_Router {
 	 */
 	private static function route_clause( array $clause, array $field ): ?array {
 		$compare = strtoupper( trim( (string) ( $clause['compare'] ?? '=' ) ) );
-		$type    = strtoupper( trim( (string) ( $clause['type'] ?? '' ) ) );
-		$type    = '' === $type ? 'CHAR' : $type;
-		$value   = $clause['value'] ?? '';
-		$kind    = $field['type'] ?? 'text';
-		$multi   = in_array( $compare, array( 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN' ), true );
+		// Without 'value', WP_Meta_Query checks only that the key exists (it adds a
+		// value condition only when one is set): HivePress's featured-listing
+		// lookup, run on every search page, is array( 'key' => 'hp_featured' ).
+		if ( ! array_key_exists( 'value', $clause ) && ! in_array( $compare, array( 'EXISTS', 'NOT EXISTS' ), true ) ) {
+			$compare = 'EXISTS';
+		}
+		$type  = strtoupper( trim( (string) ( $clause['type'] ?? '' ) ) );
+		$type  = '' === $type ? 'CHAR' : $type;
+		$value = $clause['value'] ?? '';
+		$kind  = $field['type'] ?? 'text';
+		$multi = in_array( $compare, array( 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN' ), true );
 
 		if ( ! in_array( $compare, self::COMPARES, true ) || ( ! $multi && is_array( $value ) ) ) {
 			return null;
@@ -721,7 +750,56 @@ class TMDO_Post_Query_Router {
 	 * @return string
 	 */
 	private static function routed_request( string $request, \WP_Query $query ): string {
-		return self::flat_first( self::without_found_rows( $request ), $query );
+		return self::copy_ordered( self::flat_first( self::without_found_rows( $request ), $query ), $query );
+	}
+
+	/**
+	 * The copy route's request without WordPress's GROUP BY (when the flat row
+	 * is the only join) and with posts.ID tie-breaks read as the flat post_id,
+	 * each in its own direction, once. MariaDB then walks the
+	 * (post_status, post_date, post_id) index and stops at the LIMIT instead
+	 * of sorting every match (dev36, 235k of 1.3M listings: 1.7 s → 3 ms).
+	 *
+	 * @param string    $request SELECT statement.
+	 * @param \WP_Query $query   Current WP_Query.
+	 * @return string
+	 */
+	private static function copy_ordered( string $request, \WP_Query $query ): string {
+		$copy = $query->get( self::COPY_VAR );
+		if ( empty( $copy ) ) {
+			return $request;
+		}
+		global $wpdb;
+		$tie = '`' . self::table_alias( $copy['post_type'], $copy['group'] ) . '`.`post_id` ';
+		return (string) preg_replace_callback(
+			'/\bORDER BY\b(?!.*\bORDER BY\b).*$/s',
+			static function ( $m ) use ( $wpdb, $tie ) {
+				$order = (string) preg_replace_callback(
+					'/`?' . preg_quote( $wpdb->posts, '/' ) . '`?\.`?ID`?(?!\w)(?:\s+(ASC|DESC)\b)?/i',
+					static fn( $id ) => $tie . ( 'DESC' === strtoupper( $id[1] ?? '' ) ? 'DESC' : 'ASC' ),
+					$m[0]
+				);
+				return (string) preg_replace( '/(,\s*' . preg_quote( $tie, '/' ) . '(ASC|DESC))(\s*,\s*' . preg_quote( $tie, '/' ) . '\2)+/', '$1', $order );
+			},
+			self::without_group_by( $request )
+		);
+	}
+
+	/**
+	 * WordPress groups by posts.ID for any tax or meta query. With a flat row
+	 * (one per post) as the only join there is nothing to collapse, and the
+	 * GROUP BY makes MySQL sort the whole match in a temporary table
+	 * (WooCommerce's product_visibility NOT IN on searches is a subquery).
+	 *
+	 * @param string $request SELECT statement.
+	 * @return string
+	 */
+	private static function without_group_by( string $request ): string {
+		global $wpdb;
+		if ( 1 !== preg_match_all( '/\bJOIN\b/i', $request ) ) {
+			return $request;
+		}
+		return (string) preg_replace( '/\s+GROUP BY\s+`?' . preg_quote( $wpdb->posts, '/' ) . '`?\.`?ID`?(?=\s)/', ' ', $request, 1 );
 	}
 
 	/**
@@ -790,17 +868,18 @@ class TMDO_Post_Query_Router {
 		if ( 1 !== $replaced ) {
 			return $request;
 		}
-		// WordPress groups by posts.ID for any tax or meta query. With the flat row
-		// (one per post) as the only join there is nothing to collapse, and the
-		// GROUP BY makes MySQL sort the whole match in a temporary table
-		// (WooCommerce's product_visibility NOT IN on searches is a subquery).
-		if ( 1 === preg_match_all( '/\bJOIN\b/i', (string) $flat_first ) ) {
-			$flat_first = preg_replace( '/\s+GROUP BY\s+`?' . preg_quote( $wpdb->posts, '/' ) . '`?\.`?ID`?(?=\s)/', ' ', (string) $flat_first, 1 );
-		}
-		// Tie-breaks on posts.ID (ours, and any a plugin appended) read the flat post_id.
+		$flat_first = self::without_group_by( (string) $flat_first );
+		// Tie-breaks on posts.ID (ours, and any a plugin appended) read the flat
+		// post_id, once, in the sort's direction: a (column, post_id) index then
+		// returns rows in order with no filesort. Ties are ordered by ID the same
+		// way as the column (natively ID DESC); pagination stays stable.
+		$tie        = "`{$alias}`.`post_id` " . ( 'ASC' === strtoupper( (string) $sort['order'] ) ? 'ASC' : 'DESC' );
 		$flat_first = preg_replace_callback(
 			'/\bORDER BY\b(?!.*\bORDER BY\b).*$/s',
-			static fn( $m ) => preg_replace( '/`?' . preg_quote( $wpdb->posts, '/' ) . '`?\.`?ID`?(?!\w)/', "`{$alias}`.`post_id`", $m[0] ),
+			static function ( $m ) use ( $wpdb, $tie ) {
+				$order = (string) preg_replace( '/`?' . preg_quote( $wpdb->posts, '/' ) . '`?\.`?ID`?(?!\w)(\s+(ASC|DESC)\b)?/i', $tie, $m[0] );
+				return (string) preg_replace( '/(,\s*' . preg_quote( $tie, '/' ) . ')(\s*,\s*' . preg_quote( $tie, '/' ) . ')+/', '$1', $order );
+			},
 			(string) $flat_first
 		);
 		return (string) preg_replace( '/^\s*SELECT\s/', 'SELECT STRAIGHT_JOIN ', (string) $flat_first, 1 );

readme.txt

@@ -4,7 +4,7 @@ Tags: performance, database, postmeta, optimization, hivepress
 Requires at least: 6.0
 Tested up to: 6.9
 Requires PHP: 8.1
-Stable tag: 1.3.0
+Stable tag: 1.4.0
 License: GPLv2 or later
 License URI: https://www.gnu.org/licenses/gpl-2.0.html
 
@@ -107,6 +107,13 @@ The Classifier tab analyzes your existing `wp_postmeta` data (access frequency,
 
 == Changelog ==
 
+= 1.4.0 =
+* Flat-first sorts read the ID tie-break from the flat post_id, so a declared (column, post_id) index returns rows in order; ties now follow the sort direction
+* Meta clauses without a value route as EXISTS; HivePress's featured-listing lookup on every search page uses the flat table
+* Date-ordered routed searches drop the redundant GROUP BY and use a (post_status, post_date, post_id) index (replace the index on the tables listed in `tmdo_post_status_columns`; `wp tmdo post-status-sync` also adds the copy columns to every other post group)
+* Rows rebuilt by the migration engine keep their status/date copies and invalidate cached routed counts
+* Live test tools no longer flush the object cache
+
 = 1.3.0 =
 * Declared flat-table indexes are added only from WP-CLI or WP-Cron, one process at a time (MySQL GET_LOCK); web requests schedule `tmdo_ensure_group_indexes`, and doctor lists indexes not added yet
 * Routed searches with post__not_in count from a cached base count minus the excluded posts; the cache key ignores wpdb's per-request placeholder escape and follows post saves and managed-key writes only, not every post meta write (HivePress keyword + price search no longer slower than native)

tests/integration/PostQueryRouterCopyTest.php

@@ -31,7 +31,7 @@ class PostQueryRouterCopyTest extends TestCase {
 	protected function setUp(): void {
 		global $wpdb;
 		$wpdb->query( 'DROP TABLE IF EXISTS `' . self::TABLE . '`' );
-		$wpdb->query( 'CREATE TABLE `' . self::TABLE . "` ( id BIGINT NOT NULL AUTO_INCREMENT, post_id BIGINT NOT NULL, rc_price DECIMAL(18,6) DEFAULT NULL, post_status VARCHAR(20) DEFAULT NULL, post_date DATETIME DEFAULT NULL, PRIMARY KEY (id), UNIQUE KEY uk_entity (post_id), KEY idx_post_status_date (post_status, post_date) ) ENGINE=InnoDB" );
+		$wpdb->query( 'CREATE TABLE `' . self::TABLE . "` ( id BIGINT NOT NULL AUTO_INCREMENT, post_id BIGINT NOT NULL, rc_price DECIMAL(18,6) DEFAULT NULL, post_status VARCHAR(20) DEFAULT NULL, post_date DATETIME DEFAULT NULL, PRIMARY KEY (id), UNIQUE KEY uk_entity (post_id), KEY idx_post_status_date_id (post_status, post_date, post_id) ) ENGINE=InnoDB" );
 		$wpdb->query( 'INSERT INTO `' . self::TABLE . "` (post_id, rc_price, post_status, post_date) VALUES (1, 10, 'publish', '2026-01-01 00:00:00')" );
 
 		$GLOBALS['_wp_options']  = array( TMDO_Post_Status_Sync::OPTION => array( 'rc_core' => 'ready' ) );
@@ -58,6 +58,55 @@ class PostQueryRouterCopyTest extends TestCase {
 		$mode->setValue( null, null );
 	}
 
+	/**
+	 * The full request WordPress would build for the routed search, after posts_request.
+	 *
+	 * @param string $extra_join Another JOIN (a tax query's).
+	 * @param string $ties       ID tie-breaks plugins appended.
+	 */
+	private function request( string $extra_join = '', string $ties = ', {posts}.ID DESC, {posts}.ID DESC' ): string {
+		global $wpdb;
+		$ties  = str_replace( '{posts}', $wpdb->posts, $ties );
+		$query = new WP_Query();
+		foreach ( array(
+			'post_type'   => 'rc_item',
+			'post_status' => 'publish',
+			'meta_query'  => array( array( 'key' => 'rc_price', 'value' => array( 5, 20 ), 'compare' => 'BETWEEN', 'type' => 'NUMERIC' ) ),
+		) as $k => $v ) {
+			$query->set( $k, $v );
+		}
+		$router = new TMDO_Post_Query_Router();
+		$router->pre_get_posts( $query );
+		$request = 'SELECT SQL_CALC_FOUND_ROWS wp_posts.ID FROM wp_posts ' . $router->posts_join( $extra_join, $query )
+			. ' WHERE 1=1 ' . $router->posts_where( " AND wp_posts.post_status = 'publish'", $query )
+			. " GROUP BY {$wpdb->posts}.ID ORDER BY " . $router->posts_orderby( 'wp_posts.post_date DESC', $query ) . $ties . ' LIMIT 0, 10';
+		return $router->posts_request( $request, $query );
+	}
+
+	/**
+	 * 2.4 PR-128: with GROUP BY or a posts.ID tie-break MariaDB sorts every
+	 * match (dev36, 235k of 1.3M listings: 1.7 s); without them it walks
+	 * (post_status, post_date, post_id) backwards and stops at the LIMIT (3 ms).
+	 */
+	public function test_copy_route_orders_by_the_flat_date_and_post_id_without_group_by(): void {
+		$sql = $this->request();
+
+		$this->assertStringNotContainsString( 'GROUP BY', $sql, 'one flat row per post: nothing to collapse' );
+		$this->assertStringEndsWith( 'ORDER BY ' . self::ALIAS . '.`post_date` DESC, ' . self::ALIAS . '.`post_id` DESC LIMIT 0, 10', $sql );
+	}
+
+	public function test_copy_route_keeps_each_tie_break_direction(): void {
+		$this->assertStringEndsWith( 'ORDER BY ' . self::ALIAS . '.`post_date` DESC, ' . self::ALIAS . '.`post_id` ASC LIMIT 0, 10', $this->request( '', ', {posts}.ID ASC' ) );
+		$this->assertStringEndsWith( 'ORDER BY ' . self::ALIAS . '.`post_date` DESC LIMIT 0, 10', $this->request( '', '' ) );
+	}
+
+	public function test_copy_route_keeps_group_by_with_another_join(): void {
+		global $wpdb;
+		$sql = $this->request( " LEFT JOIN wp_term_relationships ON ({$wpdb->posts}.ID = wp_term_relationships.object_id)" );
+
+		$this->assertStringContainsString( "GROUP BY {$wpdb->posts}.ID", $sql );
+	}
+
 	/** @return array{join:string, where:string, orderby:string} */
 	private function sql( array $vars ): array {
 		$query = new WP_Query();

tests/integration/PostQueryRouterFoundRowsTest.php

@@ -226,14 +226,14 @@ class PostQueryRouterFoundRowsTest extends TestCase {
 	 *
 	 * @return array{0:TMDO_Post_Query_Router, 1:WP_Query, 2:string}
 	 */
-	private function sorted( string $compare = '>=' ): array {
+	private function sorted( string $compare = '>=', string $order = 'DESC' ): array {
 		global $wpdb;
 		$query = new WP_Query();
 		$query->set( 'post_type', 'fr_item' );
 		$query->set( 'post_status', 'publish' );
 		$query->set( 'meta_query', array( 'price' => array( 'key' => 'fr_price', 'value' => 15, 'compare' => $compare, 'type' => 'NUMERIC' ) ) );
 		$query->set( 'orderby', 'price' );
-		$query->set( 'order', 'DESC' );
+		$query->set( 'order', $order );
 		$router = new TMDO_Post_Query_Router();
 		$router->pre_get_posts( $query );
 
@@ -252,11 +252,26 @@ class PostQueryRouterFoundRowsTest extends TestCase {
 		$this->assertStringStartsWith( 'SELECT STRAIGHT_JOIN ', $sql );
 		$this->assertStringContainsString( 'FROM `' . self::TABLE . '` AS `wpdoflat_fr_item_fr_core` INNER JOIN ' . $wpdb->posts . ' ON', $sql );
 		$this->assertStringNotContainsString( 'LEFT JOIN `' . self::TABLE . '`', $sql );
-		$this->assertStringEndsWith( 'ORDER BY `wpdoflat_fr_item_fr_core`.`fr_price` DESC, `wpdoflat_fr_item_fr_core`.`post_id` DESC, `wpdoflat_fr_item_fr_core`.`post_id` DESC LIMIT 0, 10', $sql, 'posts.ID tie-breaks read the flat post_id' );
+		$this->assertStringEndsWith( 'ORDER BY `wpdoflat_fr_item_fr_core`.`fr_price` DESC, `wpdoflat_fr_item_fr_core`.`post_id` DESC LIMIT 0, 10', $sql, 'posts.ID tie-breaks read the flat post_id, once' );
 		$this->assertSame( array( '3', '2' ), $wpdb->get_col( $sql ) );
 		$this->assertSame( $wpdb->get_col( str_replace( 'SQL_CALC_FOUND_ROWS ', '', $request ) ), $wpdb->get_col( $sql ) );
 	}
 
+	/**
+	 * The ID tie-break follows the sort direction, so a (column, post_id)
+	 * index returns rows in order with no filesort (2.4 PR-118); ties are
+	 * ordered by ID the same way as the column.
+	 */
+	public function test_flat_first_tie_break_follows_the_sort_direction(): void {
+		global $wpdb;
+		list( $router, $query, $request ) = $this->sorted( '>=', 'ASC' );
+
+		$sql = $router->posts_request( $request, $query );
+
+		$this->assertStringEndsWith( 'ORDER BY `wpdoflat_fr_item_fr_core`.`fr_price` ASC, `wpdoflat_fr_item_fr_core`.`post_id` ASC LIMIT 0, 10', $sql );
+		$this->assertSame( array( '2', '3' ), $wpdb->get_col( $sql ) );
+	}
+
 	public function test_date_ordered_filtered_request_keeps_wordpress_join_order(): void {
 		list( $router, $query, $request ) = $this->routed();
 

tests/integration/PostQueryRouterTest.php

@@ -412,4 +412,71 @@ class PostQueryRouterTest extends TestCase {
 
 		$this->assertStringContainsString( "LIKE '%B1\\\\_1\\\\%%'", $router->posts_where( '', $query ) );
 	}
+
+	/**
+	 * A clause with no value tests only that the key exists (WP_Meta_Query adds
+	 * a value condition only when 'value' is set), so it routes as EXISTS.
+	 * HivePress's featured-listing lookup on every search page is one:
+	 * array( 'key' => 'hp_featured' ) — it kept the whole query native (2.4 PR-122).
+	 */
+	public function test_a_clause_without_a_value_routes_as_exists(): void {
+		$this->set_post_mode( 'aeav_only' );
+		$router = new WPDO_Post_Query_Router();
+		$query  = $this->make_query(
+			array(
+				'post_type'  => 'product',
+				'meta_query' => array(
+					array( 'key' => '_stock' ),
+					array( 'key' => '_price', 'value' => array( 10, 20 ), 'compare' => 'BETWEEN', 'type' => 'NUMERIC' ),
+				),
+			)
+		);
+		$router->pre_get_posts( $query );
+
+		$this->assertEmpty( $query->get( 'meta_query' ), 'both clauses routed' );
+		$this->assertStringContainsString( '`_stock` IS NOT NULL', $router->posts_where( '', $query ) );
+	}
+
+	/**
+	 * HivePress's featured-listing lookup (Attribute::set_search_query()): the
+	 * search's meta query, including its sort group, plus meta_key hp_featured,
+	 * ordered at random. The sort group (key NOT EXISTS OR key EXISTS) matches
+	 * every post, so unused for ordering it is dropped; meta_key without a
+	 * value or a meta_value sort tests that the key exists (2.4 PR-122).
+	 */
+	public function test_hivepress_featured_lookup_is_routed(): void {
+		$this->set_post_mode( 'aeav_only' );
+		$router = new WPDO_Post_Query_Router();
+		$query  = $this->make_query(
+			array(
+				'post_type'  => 'product',
+				'meta_key'   => '_stock',
+				'orderby'    => 'rand',
+				'meta_query' => array(
+					array(
+						'relation'      => 'OR',
+						'price__order' => array( 'key' => '_price', 'compare' => 'NOT EXISTS', 'type' => 'DECIMAL' ),
+						array( 'key' => '_price', 'compare' => 'EXISTS', 'type' => 'DECIMAL' ),
+					),
+					array( 'key' => '_price', 'value' => array( 10, 20 ), 'compare' => 'BETWEEN', 'type' => 'NUMERIC' ),
+				),
+			)
+		);
+		$router->pre_get_posts( $query );
+
+		$this->assertSame( '', $query->get( 'meta_key' ), 'meta_key routed' );
+		$this->assertEmpty( array_filter( (array) $query->get( 'meta_query' ), 'is_array' ), 'sort group dropped, filter routed' );
+		$where = $router->posts_where( '', $query );
+		$this->assertStringContainsString( '`_stock` IS NOT NULL', $where );
+		$this->assertStringContainsString( 'BETWEEN', $where );
+	}
+
+	public function test_meta_key_with_a_value_is_left_alone(): void {
+		$this->set_post_mode( 'aeav_only' );
+		$router = new WPDO_Post_Query_Router();
+		$query  = $this->make_query( array( 'post_type' => 'product', 'meta_key' => '_stock', 'meta_value' => '5' ) );
+		$router->pre_get_posts( $query );
+
+		$this->assertSame( '_stock', $query->get( 'meta_key' ) );
+	}
 }

tests/integration/PostStatusSyncTest.php

@@ -25,6 +25,9 @@ class PostStatusSyncTest extends TestCase {
 			'includes/adapters/class-tmdo-adapter-post.php',
 			'includes/engine/class-tmdo-hook-bus.php',
 			'includes/engine/class-tmdo-post-status-sync.php',
+			'includes/engine/class-tmdo-entity-migration-engine.php',
+			'includes/integrations/class-tmdo-post-fields.php',
+			'includes/query/class-tmdo-post-query-router.php',
 		) as $file ) {
 			require_once $base . $file;
 		}
@@ -81,9 +84,34 @@ class PostStatusSyncTest extends TestCase {
 		return $out;
 	}
 
-	private function has_index( string $table ): bool {
+	/** @return array<string, string[]> index name → columns */
+	private function indexes( string $table ): array {
 		global $wpdb;
-		return in_array( 'idx_post_status_date', array_column( (array) $wpdb->get_results( "SHOW INDEX FROM `{$table}`", ARRAY_A ), 'Key_name' ), true );
+		$out = array();
+		foreach ( (array) $wpdb->get_results( "SHOW INDEX FROM `{$table}`", ARRAY_A ) as $row ) {
+			$out[ $row['Key_name'] ][ (int) $row['Seq_in_index'] - 1 ] = $row['Column_name'];
+		}
+		return $out;
+	}
+
+	private function has_index( string $table ): bool {
+		return array( 'post_status', 'post_date', 'post_id' ) === ( $this->indexes( $table )['idx_post_status_date_id'] ?? null );
+	}
+
+	/**
+	 * 2.4 PR-128: the date route's ID tie-break is read from post_id, which the
+	 * index must end with; the 2.2 two-column index is replaced, not kept beside it.
+	 */
+	public function test_run_replaces_the_two_column_index_of_existing_tables(): void {
+		global $wpdb;
+		$wpdb->query( 'ALTER TABLE `' . self::A . '` ADD COLUMN post_status VARCHAR(20) COLLATE utf8mb4_unicode_520_ci DEFAULT NULL, ADD COLUMN post_date DATETIME DEFAULT NULL, ADD INDEX idx_post_status_date (post_status, post_date)' );
+		$GLOBALS['_wp_options'][ TMDO_Post_Status_Sync::OPTION ] = array( 'ps_a' => 'ready' );
+
+		TMDO_Post_Status_Sync::run();
+
+		$this->assertTrue( $this->has_index( self::A ) );
+		$this->assertArrayNotHasKey( 'idx_post_status_date', $this->indexes( self::A ) );
+		$this->assertSame( 'ready', TMDO_Post_Status_Sync::state( 'ps_a' ) );
 	}
 
 	public function test_run_adds_the_columns_copies_every_row_and_marks_groups_ready(): void {
@@ -173,6 +201,64 @@ class PostStatusSyncTest extends TestCase {
 		$this->assertNotContains( 'post_status', $wpdb->get_col( 'SHOW COLUMNS FROM `' . self::A . '`' ) );
 	}
 
+	/**
+	 * The migration engine (backfill, drift-check --fix) REPLACEs whole rows:
+	 * without the copies, a rebuilt row had NULL post_status, which turns the
+	 * status/date copy route off for the whole group (2.4 PR-127).
+	 */
+	public function test_a_row_rebuilt_from_native_keeps_its_copies(): void {
+		global $wpdb;
+		TMDO_Post_Status_Sync::run();
+		$GLOBALS['_wp_posts'][2] = (object) array( 'ID' => 2, 'post_type' => 'hp_listing', 'post_status' => 'draft', 'post_date' => '2026-02-01 10:00:00' );
+		$GLOBALS['_wp_posts'][3] = (object) array( 'ID' => 3, 'post_type' => 'hp_listing', 'post_status' => 'pending', 'post_date' => '2026-03-01 10:00:00' );
+		$wpdb->query( "CREATE TABLE IF NOT EXISTS `{$wpdb->postmeta}` ( meta_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT, post_id BIGINT UNSIGNED NOT NULL DEFAULT 0, meta_key VARCHAR(255) DEFAULT NULL, meta_value LONGTEXT, PRIMARY KEY (meta_id) ) ENGINE=InnoDB" );
+		try {
+			$wpdb->query( "INSERT INTO `{$wpdb->postmeta}` (post_id, meta_key, meta_value) VALUES (2, 'k', 'a2-native'), (3, 'k', 'a3-native')" );
+
+			WPDO_Entity_Migration_Engine::migrate_entity( 'post', 'ps_a', 2 ); // Existing row.
+			WPDO_Entity_Migration_Engine::migrate_entity( 'post', 'ps_a', 3 ); // New row.
+		} finally {
+			$wpdb->query( "DROP TABLE IF EXISTS `{$wpdb->postmeta}`" );
+		}
+
+		$this->assertSame( array( 'draft', '2026-02-01 10:00:00' ), $this->copies( self::A )[2] );
+		$this->assertSame( array( 'pending', '2026-03-01 10:00:00' ), $this->copies( self::A )[3] );
+	}
+
+	/**
+	 * Backfills and drift-check --fix rebuild rows outside the Hook Bus: the
+	 * routed counts cached for the old rows must go (2.4 PR-129; dev36: a
+	 * vendor search kept counting 21515 of 21522 matches after a fix).
+	 */
+	public function test_rebuilding_post_rows_invalidates_cached_routed_counts(): void {
+		global $wpdb;
+		$status = $wpdb->prefix . TMDO_TABLE_PREFIX . 'migration_status';
+		$wpdb->query( "CREATE TABLE IF NOT EXISTS `{$wpdb->postmeta}` ( meta_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT, post_id BIGINT UNSIGNED NOT NULL DEFAULT 0, meta_key VARCHAR(255) DEFAULT NULL, meta_value LONGTEXT, PRIMARY KEY (meta_id) ) ENGINE=InnoDB" );
+		$wpdb->query( "CREATE TABLE IF NOT EXISTS `{$status}` ( id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT, entity_type VARCHAR(50) NOT NULL, group_name VARCHAR(50) NOT NULL, last_id BIGINT UNSIGNED NOT NULL DEFAULT 0, total_migrated BIGINT UNSIGNED NOT NULL DEFAULT 0, status VARCHAR(20) NOT NULL DEFAULT 'pending', started_at DATETIME DEFAULT NULL, completed_at DATETIME DEFAULT NULL, PRIMARY KEY (id), UNIQUE KEY entity_group (entity_type, group_name) ) ENGINE=InnoDB" );
+		$version = static fn() => $GLOBALS['_wp_last_changed'][ TMDO_Post_Query_Router::COUNT_VERSION_GROUP ] ?? null;
+		try {
+			$wpdb->query( "INSERT INTO `{$wpdb->postmeta}` (post_id, meta_key, meta_value) VALUES (2, 'k', 'a2-native')" );
+
+			$GLOBALS['_wp_last_changed'][ TMDO_Post_Query_Router::COUNT_VERSION_GROUP ] = 'before';
+			TMDO_Entity_Migration_Engine::migrate_group( 'post', 'ps_a', array( 'resume' => false, 'sleep_ms' => 0, 'dry_run' => true ) );
+			$this->assertSame( 'before', $version(), 'a dry run writes nothing' );
+
+			foreach ( array(
+				'migrate_entity'      => static fn() => TMDO_Entity_Migration_Engine::migrate_entity( 'post', 'ps_a', 2 ),
+				'migrate_group'       => static fn() => TMDO_Entity_Migration_Engine::migrate_group( 'post', 'ps_a', array( 'resume' => false, 'sleep_ms' => 0 ) ),
+				'migrate_group_batch' => static fn() => TMDO_Entity_Migration_Engine::migrate_group_batch( 'post', 'ps_a' ),
+			) as $path => $run ) {
+				TMDO_Entity_Migration_Engine::reset_checkpoint( 'post', 'ps_a' );
+				$GLOBALS['_wp_last_changed'][ TMDO_Post_Query_Router::COUNT_VERSION_GROUP ] = 'before';
+				$run();
+				$this->assertNotSame( 'before', $version(), $path );
+			}
+		} finally {
+			$wpdb->query( "DROP TABLE IF EXISTS `{$wpdb->postmeta}`" );
+			$wpdb->query( "DROP TABLE IF EXISTS `{$status}`" );
+		}
+	}
+
 	public function test_flat_write_that_creates_a_row_fills_the_copies(): void {
 		TMDO_Post_Status_Sync::run();
 		$mode = new ReflectionProperty( WPDO_Mode_Manager::class, 'cache' );

tests/live/tools/mut.php

@@ -7,7 +7,8 @@ $mode = TMDO_Mode_Manager::get( 'post' ) . '/' . TMDO_Mode_Manager::get( 'user'
 function nat( $t, $id, $k ) { global $wpdb; $mt = $t === 'user' ? $wpdb->usermeta : $wpdb->postmeta; $c = $t === 'user' ? 'user_id' : 'post_id'; $v = $wpdb->get_col( $wpdb->prepare( "SELECT meta_value FROM $mt WHERE $c=%d AND meta_key=%s", $id, $k ) ); return $v ? implode( '|', $v ) : '∅'; }
 function flat( $t, $g, $id, $k ) { global $wpdb; $c = $t === 'user' ? 'user_id' : 'post_id'; $v = $wpdb->get_row( $wpdb->prepare( "SELECT `$k` v FROM {$wpdb->prefix}wpdo_{$t}_{$g} WHERE $c=%d", $id ) ); return $v ? ( $v->v ?? 'NULL' ) : 'NO-ROW'; }
 function row( $name, $vals ) { printf( "%-44s %s\n", $name, implode( '  ', array_map( fn( $k, $v ) => "$k=" . ( is_scalar( $v ) || is_null( $v ) ? var_export( $v, true ) : json_encode( $v ) ), array_keys( $vals ), $vals ) ) ); }
-function clear_caches( $id ) { wp_cache_flush(); clean_post_cache( $id ); }
+// Never wp_cache_flush(): with Redis Object Cache selective flush it is one server-side scan that blocks Redis for every site.
+function clear_caches( $id ) { clean_post_cache( $id ); wp_cache_flush_runtime(); }
 echo "== mode post/user = $mode\n";
 
 // T1: HivePress model update of a listing price.
@@ -42,12 +43,12 @@ row( "T5 delete_post_meta hp_featured", array( 'native' => nat( 'post', $lid, 'h
 
 // T6: user first_name via wp_update_user.
 $uid = (int) $wpdb->get_var( "SELECT ID FROM {$wpdb->users} WHERE user_login LIKE 's36v_B1p1_%' ORDER BY ID LIMIT 1" );
-$fn = 'Fn' . mt_rand( 100, 999 ); wp_update_user( array( 'ID' => $uid, 'first_name' => $fn ) ); wp_cache_flush();
+$fn = 'Fn' . mt_rand( 100, 999 ); wp_update_user( array( 'ID' => $uid, 'first_name' => $fn ) ); clean_user_cache( $uid ); wp_cache_flush_runtime();
 $u = get_userdata( $uid );
 row( "T6 user $uid first_name:=$fn", array( 'native' => nat( 'user', $uid, 'first_name' ), 'flat' => flat( 'user', 'core_profile', $uid, 'first_name' ), 'get_meta' => get_user_meta( $uid, 'first_name', true ), 'WP_User' => $u->first_name, 'wc_customer' => ( new WC_Customer( $uid ) )->get_first_name() ) );
 
 // T7: WC customer billing city via CRUD.
-$c = new WC_Customer( $uid ); $city = 'City' . mt_rand( 10, 99 ); $c->set_billing_city( $city ); $c->save(); wp_cache_flush();
+$c = new WC_Customer( $uid ); $city = 'City' . mt_rand( 10, 99 ); $c->set_billing_city( $city ); $c->save(); clean_user_cache( $uid ); wp_cache_flush_runtime();
 row( "T7 WC_Customer billing_city:=$city", array( 'native' => nat( 'user', $uid, 'billing_city' ), 'flat' => flat( 'user', 'commerce', $uid, 'billing_city' ), 'get_meta' => get_user_meta( $uid, 'billing_city', true ), 'wc_customer' => ( new WC_Customer( $uid ) )->get_billing_city() ) );
 
 // T8: delete a listing → flat row?
@@ -57,5 +58,5 @@ row( "T8 wp_delete_post $d", array( 'posts' => (int) $wpdb->get_var( "SELECT COU
 
 // T9: HP review → listing rating recompute.
 $before = get_post_meta( $lid, 'hp_rating_count', true );
-$rv = ( new Models\Review() )->fill( array( 'text' => 'mut', 'rating' => 5, 'approved' => 1, 'author' => $uid, 'author__display_name' => 'x', 'author__email' => 'x@example.test', 'listing' => $lid ) ); $rv->save(); wp_cache_flush();
+$rv = ( new Models\Review() )->fill( array( 'text' => 'mut', 'rating' => 5, 'approved' => 1, 'author' => $uid, 'author__display_name' => 'x', 'author__email' => 'x@example.test', 'listing' => $lid ) ); $rv->save(); clean_post_cache( $lid ); wp_cache_flush_runtime();
 row( "T9 add review (count was $before)", array( 'native' => nat( 'post', $lid, 'hp_rating_count' ), 'flat' => flat( 'post', 'hp_listing_core', $lid, 'hp_rating_count' ), 'hp_model' => Models\Listing::query()->get_by_id( $lid )->get_rating_count() ) );

tests/live/tools/qbench.php

@@ -40,7 +40,12 @@ foreach ( $cases as $name => $qa ) {
 	$err   = '';
 	$sql   = '';
 	for ( $i = 0; $i < $iters; $i++ ) {
-		wp_cache_flush_group( 'tmdo_found_rows' );
+		// Fresh routed counts without wp_cache_flush_group() (a Redis-blocking server-side scan).
+		if ( method_exists( 'TMDO_Post_Query_Router', 'bump_count_version' ) ) {
+			TMDO_Post_Query_Router::bump_count_version();
+		} else {
+			wp_cache_set_last_changed( 'posts' ); // Core < 1.3.0 keyed the counts on posts' last_changed.
+		}
 		$wpdb->last_error = '';
 		$t = microtime( true );
 		$q = new WP_Query( $qa + array( 'fields' => 'ids', 'cache_results' => false, 'suppress_filters' => false ) );

tests/unit/EntityRegistryIndexesTest.php

@@ -14,7 +14,9 @@ class EntityRegistryIndexesTest extends TestCase {
 
 	protected function setUp(): void {
 		TMDO_Entity_Registry::init();
-		TMDO_Entity_Registry::register_adapter( 'post', $this->createMock( TMDO_Entity_Adapter_Interface::class ) );
+		$adapter = $this->createMock( TMDO_Entity_Adapter_Interface::class );
+		$adapter->method( 'get_entity_id_column' )->willReturn( 'post_id' );
+		TMDO_Entity_Registry::register_adapter( 'post', $adapter );
 	}
 
 	private function fields(): array {
@@ -37,6 +39,16 @@ class EntityRegistryIndexesTest extends TestCase {
 		$this->assertSame( array( 'ok' => array( 'x_price' ) ), TMDO_Entity_Registry::get_group_indexes( 'post', 'x_core' ) );
 	}
 
+	/**
+	 * A sort index ends with the entity ID, so a flat-first search ordered by a
+	 * column with the ID tie-break reads the index in order (2.4 PR-118).
+	 */
+	public function test_an_index_may_end_with_the_entity_id_column(): void {
+		TMDO_Entity_Registry::register_group( 'post', 'x_core', $this->fields(), array( 'indexes' => array( 'price_id' => array( 'x_price', 'post_id' ), 'id_first' => array( 'post_id', 'x_price' ) ) ) );
+
+		$this->assertSame( array( 'price_id' => array( 'x_price', 'post_id' ) ), TMDO_Entity_Registry::get_group_indexes( 'post', 'x_core' ), 'the ID only as the last column' );
+	}
+
 	public function test_indexes_leave_the_field_definition_and_hash_alone(): void {
 		TMDO_Entity_Registry::register_group( 'post', 'plain', $this->fields() );
 		TMDO_Entity_Registry::register_group( 'post', 'indexed', $this->fields(), array( 'indexes' => array( 'flag_price' => array( 'x_flag', 'x_price' ) ) ) );