From 7c019a2bd9861b99ead0f236d7ac1448c7c9c534 Mon Sep 17 00:00:00 2001
From: Ben Hollis <ben.hollis@databricks.com>
Date: Sat, 12 Sep 2026 02:27:54 +0000
Subject: [PATCH] Avoid plan comparison when change logging is disabled

---
 .../org/apache/spark/internal/Logging.scala   |  4 +++
 .../sql/catalyst/rules/RuleExecutor.scala     | 33 +++++++++----------
 2 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/common/utils/src/main/scala/org/apache/spark/internal/Logging.scala b/common/utils/src/main/scala/org/apache/spark/internal/Logging.scala
index 3fac57dbe5dda..2aba75dd897c0 100644
--- a/common/utils/src/main/scala/org/apache/spark/internal/Logging.scala
+++ b/common/utils/src/main/scala/org/apache/spark/internal/Logging.scala
@@ -307,6 +307,10 @@ trait Logging {
     log.isTraceEnabled
   }
 
+  protected def withLogLevel(level: Slf4jLevel)(f: => Unit): Unit = {
+    if (log.isEnabledForLevel(level)) f
+  }
+
   protected def logBasedOnLevel(level: Slf4jLevel)(f: => MessageWithContext): Unit = {
     level match {
       case Slf4jLevel.TRACE => logTrace(f.message)
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/rules/RuleExecutor.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/rules/RuleExecutor.scala
index b5a35608a54e6..8a04a5431a68c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/rules/RuleExecutor.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/rules/RuleExecutor.scala
@@ -55,25 +55,24 @@ class PlanChangeLogger[TreeType <: TreeNode[_]] extends Logging {
   private val logBatches = SQLConf.get.planChangeBatches.map(Utils.stringToSeq)
 
   def logRule(ruleName: String, oldPlan: TreeType, newPlan: TreeType): Unit = {
-    if (!newPlan.fastEquals(oldPlan)) {
-      if (logRules.isEmpty || logRules.get.contains(ruleName)) {
-        def message(): MessageWithContext = {
-          val oldPlanStringWithOutput = oldPlan.treeString(verbose = false,
-            printOutputColumns = true)
-          val newPlanStringWithOutput = newPlan.treeString(verbose = false,
-            printOutputColumns = true)
-          // scalastyle:off line.size.limit
+    withLogLevel(logLevel) {
+      if ((logRules.isEmpty || logRules.get.contains(ruleName)) &&
+          !newPlan.fastEquals(oldPlan)) {
+        val oldPlanStringWithOutput = oldPlan.treeString(verbose = false,
+          printOutputColumns = true)
+        val newPlanStringWithOutput = newPlan.treeString(verbose = false,
+          printOutputColumns = true)
+        // scalastyle:off line.size.limit
+        logBasedOnLevel(logLevel) {
           log"""
-             |=== Applying Rule ${MDC(RULE_NAME, ruleName)} ===
-             |${MDC(QUERY_PLAN, sideBySide(oldPlan.treeString, newPlan.treeString).mkString("\n"))}
-             |
-             |Output Information:
-             |${MDC(QUERY_PLAN, sideBySide(oldPlanStringWithOutput, newPlanStringWithOutput).mkString("\n"))}
-           """.stripMargin
-           // scalastyle:on line.size.limit
+            |=== Applying Rule ${MDC(RULE_NAME, ruleName)} ===
+            |${MDC(QUERY_PLAN, sideBySide(oldPlan.treeString, newPlan.treeString).mkString("\n"))}
+            |
+            |Output Information:
+            |${MDC(QUERY_PLAN, sideBySide(oldPlanStringWithOutput, newPlanStringWithOutput).mkString("\n"))}
+          """.stripMargin
         }
-
-        logBasedOnLevel(logLevel)(message())
+        // scalastyle:on line.size.limit
       }
     }
   }