fix: add ServerId index to Server_Stats to speed up per-server stats lookup

Server.php's ReadStats() query (SELECT ... WHERE ServerId=? ORDER BY
TimeStamp DESC LIMIT 1) had no supporting index, forcing a full table
scan on every page load that shows server stats. Add a composite
(ServerId, TimeStamp) index via zm_update-1.39.18.sql (idempotent,
checked against INFORMATION_SCHEMA.STATISTICS) and zm_create.sql.in
for fresh installs. Keep the existing TimeStamp-only index, since
zmstats.pl's prune DELETE filters by TimeStamp alone.

Also query ReadStats() with the server's actual Id() instead of
coercing Id() <= 1 to 0.

Bump version.txt and the redhat spec Version to 1.39.18.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Q7jeoG8ptXRpXxif2JqkD7

db/zm_create.sql.in

@@ -846,6 +846,7 @@ CREATE TABLE `Server_Stats` (
 );
 
 CREATE INDEX `Server_Stats_TimeStamp_idx` ON `Server_Stats` (`TimeStamp`);
+CREATE INDEX `Server_Stats_ServerId_idx` ON `Server_Stats` (`ServerId`, `TimeStamp`);
 
 --
 -- Table structure for table `Stats`

db/zm_update-1.39.18.sql

@@ -0,0 +1,19 @@
+--
+-- Add a composite index on Server_Stats to speed up the per-server latest-stats
+-- lookup (SELECT * FROM Server_Stats WHERE ServerId=? ORDER BY TimeStamp DESC LIMIT 1),
+-- which was previously a full table scan.
+--
+
+SET @s = (SELECT IF(
+  (SELECT COUNT(*)
+    FROM INFORMATION_SCHEMA.STATISTICS
+    WHERE table_name = 'Server_Stats'
+    AND table_schema = DATABASE()
+    AND index_name = 'Server_Stats_ServerId_idx'
+  ) > 0,
+  "SELECT 'Server_Stats_ServerId_idx already exists on Server_Stats table'",
+  "ALTER TABLE `Server_Stats` ADD INDEX `Server_Stats_ServerId_idx` (`ServerId`, `TimeStamp`)"
+));
+PREPARE stmt FROM @s;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;

distros/redhat/zoneminder.spec

@@ -21,7 +21,7 @@
 %global zmtargetdistro %{?rhel:el%{rhel}}%{!?rhel:fc%{fedora}}
 
 Name: zoneminder
-Version: 1.39.11
+Version: 1.39.18
 Release: 1%{?dist}
 Summary: A camera monitoring and analysis tool
 Group: System Environment/Daemons

version.txt

@@ -1 +1 @@
-1.39.17
+1.39.18

web/includes/Server.php

@@ -46,7 +46,7 @@ class Server extends ZM_Object {
 
   public function ReadStats() {
     #ToDo: Analyze the date of the last entry, because The entry may be out of date and not updated.
-    $dbStats = dbFetchAll('SELECT * FROM Server_Stats WHERE ServerId=? ORDER BY TimeStamp DESC LIMIT 1',NULL, [$this->Id()>1 ? $this->Id() : 0]);
+    $dbStats = dbFetchAll('SELECT * FROM Server_Stats WHERE ServerId=? ORDER BY TimeStamp DESC LIMIT 1',NULL, [$this->Id()]);
     if (count($dbStats)) {
       $this->TimeUpdateStats = $dbStats[0]['TimeStamp'];
       $this->CpuLoad = $dbStats[0]['CpuLoad'];