From a334caaa2053511a77b05f74bd1c6ff219d65164 Mon Sep 17 00:00:00 2001
From: zch <zangch@mesnac.com>
Date: Mon, 27 Apr 2026 18:06:07 +0800
Subject: [PATCH] =?UTF-8?q?perf(/latestSteamInstantList):=20=E4=BC=98?=
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修改 SQL 查询方式，从设备表驱动并使用 CROSS APPLY 获取每个设备的最新记录
移除 Java 服务层不必要的过滤逻辑，直接使用优化后的查询结果
---
 .../impl/EmsRecordSteamInstantServiceImpl.java  | 11 ++---------
 .../ems/record/EmsRecordSteamInstantMapper.xml  | 17 ++++++++---------
 2 files changed, 10 insertions(+), 18 deletions(-)

diff --git a/os-ems/src/main/java/com/os/ems/record/service/impl/EmsRecordSteamInstantServiceImpl.java b/os-ems/src/main/java/com/os/ems/record/service/impl/EmsRecordSteamInstantServiceImpl.java
index 44fbd1c..abbbd19 100644
--- a/os-ems/src/main/java/com/os/ems/record/service/impl/EmsRecordSteamInstantServiceImpl.java
+++ b/os-ems/src/main/java/com/os/ems/record/service/impl/EmsRecordSteamInstantServiceImpl.java
@@ -114,16 +114,9 @@ public class EmsRecordSteamInstantServiceImpl implements IEmsRecordSteamInstantS
         List<EmsRecordSteamInstant> emsRecordSteamInstants = new ArrayList<>();
         //判断监控编码是否为空
         if (monitorCode == null){
-            //没有选择设备，monitorCode为空的时候，分组查询全部设备的最新一条记录
-            List<EmsRecordSteamInstant> allEmsRecordSteamInstants = emsRecordSteamInstantMapper
+            //没有选择设备，monitorCode为空的时候，从设备表驱动查询每个设备的最新一条记录
+            emsRecordSteamInstants = emsRecordSteamInstantMapper
                     .selectEmsRecordLatestSteamInstantList(emsRecordSteamInstant);
-            //遍历查询结果
-            for (EmsRecordSteamInstant recordSteamInstantallEmsRecordSteamInstants : allEmsRecordSteamInstants){
-                //如果有设备名称就添加到返回集合中
-                if (recordSteamInstantallEmsRecordSteamInstants.getMonitorName() != null){
-                    emsRecordSteamInstants.add(recordSteamInstantallEmsRecordSteamInstants);
-                }
-            }
         }else {
             //选择了设备，monitorCode不为空的时候，根据monitorCode查询指定设备的最新一条记录
             emsRecordSteamInstants = emsRecordSteamInstantMapper
diff --git a/os-ems/src/main/resources/mapper/ems/record/EmsRecordSteamInstantMapper.xml b/os-ems/src/main/resources/mapper/ems/record/EmsRecordSteamInstantMapper.xml
index 18e7fcd..7f411c6 100644
--- a/os-ems/src/main/resources/mapper/ems/record/EmsRecordSteamInstantMapper.xml
+++ b/os-ems/src/main/resources/mapper/ems/record/EmsRecordSteamInstantMapper.xml
@@ -213,7 +213,7 @@
     </select>
 -->
 
-    <!-- 查询每个设备的最新一条记录 -->
+    <!-- 查询每个设备的最新一条记录：从设备表驱动，每个设备只取 TOP 1，避免全表扫描 -->
     <select id="selectEmsRecordLatestSteamInstantList" parameterType="EmsRecordSteamInstant" resultMap="EmsRecordSteamInstantResult">
         SELECT
             ersi.obj_id,
@@ -230,15 +230,14 @@
             ersi.difference_press,
             ersi.record_time
         FROM
-            ems_record_steam_instant ersi
-                LEFT JOIN ems_base_monitor_info ebmi ON ersi.monitor_code = ebmi.monitor_code
-                INNER JOIN (
-                SELECT monitor_code, MAX(obj_id) AS max_obj_id
+            ems_base_monitor_info ebmi
+                CROSS APPLY (
+                SELECT TOP 1 *
                 FROM ems_record_steam_instant
-                GROUP BY monitor_code
-            ) ersi_max ON ersi.monitor_code = ersi_max.monitor_code AND ersi.obj_id = ersi_max.max_obj_id
-        ORDER BY ersi.monitor_code ASC;
-
+                WHERE monitor_code = ebmi.monitor_code
+                ORDER BY obj_id DESC
+            ) ersi
+        ORDER BY ersi.monitor_code ASC
     </select>
 
 </mapper>