From dbfacdc4afe3420d0a6e8f65ed546b0255d8d3bc Mon Sep 17 00:00:00 2001
From: zy-kkk <zhongyk10@gmail.com>
Date: Wed, 13 Sep 2023 21:40:28 +0800
Subject: [PATCH] [improvement](jdbc catalog) Optimize Loop Performance by
 Caching `isNebula` Method Result (#24260)

---
 .../org/apache/doris/jdbc/JdbcExecutor.java   | 32 ++++++++++++-------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/fe/be-java-extensions/jdbc-scanner/src/main/java/org/apache/doris/jdbc/JdbcExecutor.java b/fe/be-java-extensions/jdbc-scanner/src/main/java/org/apache/doris/jdbc/JdbcExecutor.java
index 4541de0f4c..74e65c73ab 100644
--- a/fe/be-java-extensions/jdbc-scanner/src/main/java/org/apache/doris/jdbc/JdbcExecutor.java
+++ b/fe/be-java-extensions/jdbc-scanner/src/main/java/org/apache/doris/jdbc/JdbcExecutor.java
@@ -148,11 +148,15 @@ public class JdbcExecutor {
             int columnCount = resultSetMetaData.getColumnCount();
             resultColumnTypeNames = new ArrayList<>(columnCount);
             block = new ArrayList<>(columnCount);
-            for (int i = 0; i < columnCount; ++i) {
-                if (!isNebula()) {
-                    resultColumnTypeNames.add(resultSetMetaData.getColumnClassName(i + 1));
+            if (isNebula()) {
+                for (int i = 0; i < columnCount; ++i) {
+                    block.add((Object[]) Array.newInstance(Object.class, batchSizeNum));
+                }
+            } else {
+                for (int i = 0; i < columnCount; ++i) {
+                    resultColumnTypeNames.add(resultSetMetaData.getColumnClassName(i + 1));
+                    block.add((Object[]) Array.newInstance(Object.class, batchSizeNum));
                 }
-                block.add((Object[]) Array.newInstance(Object.class, batchSizeNum));
             }
             return columnCount;
         } catch (SQLException e) {
@@ -367,16 +371,22 @@ public class JdbcExecutor {
         try {
             int columnCount = resultSetMetaData.getColumnCount();
             curBlockRows = 0;
-            do {
-                for (int i = 0; i < columnCount; ++i) {
-                    if (isNebula()) {
+
+            if (isNebula()) {
+                do {
+                    for (int i = 0; i < columnCount; ++i) {
                         block.get(i)[curBlockRows] = UdfUtils.convertObject((ValueWrapper) resultSet.getObject(i + 1));
-                    } else {
+                    }
+                    curBlockRows++;
+                } while (curBlockRows < batchSize && resultSet.next());
+            } else {
+                do {
+                    for (int i = 0; i < columnCount; ++i) {
                         block.get(i)[curBlockRows] = resultSet.getObject(i + 1);
                     }
-                }
-                curBlockRows++;
-            } while (curBlockRows < batchSize && resultSet.next());
+                    curBlockRows++;
+                } while (curBlockRows < batchSize && resultSet.next());
+            }
         } catch (SQLException e) {
             throw new UdfRuntimeException("get next block failed: ", e);
         }