From: Gustavo Martin Morcuende <gu.martinm@gmail.com>
Date: Sun, 10 Apr 2016 16:32:26 +0000 (+0200)
Subject: MyBatis ReuseBatchExecutor: comments about REUSE vs SIMPLE vs BATCH modes
X-Git-Url: https://git.gumartinm.name/?a=commitdiff_plain;h=78b127f58e071e3ac20f389a0f1a1389be9f3cd5;p=JavaForFun

MyBatis ReuseBatchExecutor: comments about REUSE vs SIMPLE vs BATCH modes
---

diff --git a/MyBatis/MyBatis-Spring-ReuseBatchExecutor/src/main/java/de/example/mybatis/spring/service/impl/ExampleServiceImpl.java b/MyBatis/MyBatis-Spring-ReuseBatchExecutor/src/main/java/de/example/mybatis/spring/service/impl/ExampleServiceImpl.java
index 4bcc2c0..0c9f2ef 100644
--- a/MyBatis/MyBatis-Spring-ReuseBatchExecutor/src/main/java/de/example/mybatis/spring/service/impl/ExampleServiceImpl.java
+++ b/MyBatis/MyBatis-Spring-ReuseBatchExecutor/src/main/java/de/example/mybatis/spring/service/impl/ExampleServiceImpl.java
@@ -61,6 +61,28 @@ public class ExampleServiceImpl implements ExampleService {
 		adTestOne.setCompanyId(2L);
 		adTestOne.setUpdatedAt(new Date());
 		adMapper.insert(adTestOne);
+		// BATCH MODE: no transaction
+		// adTestOne.id = VALUE, AUTOINCREMENT FROM DATABASE
+		// BATCH MODE: transaction
+		// adTestOne.id = null  <-------------- IF YOU WANT TO USE BATCH MODE, YOUR CODE MUST BE IMPLEMENTED KNOWING THIS KIND OF STUFF!!!!
+		// SIMPLE MODE: no transaction
+		// adTestOne.id = VALUE, AUTOINCREMENT FROM DATABASE
+		// SIMPLE MODE: transaction
+		// adTestOne.id = VALUE, AUTOINCREMENT FROM DATABASE
+		// REUSE MODE: no transaction
+		// adTestOne.id = VALUE, AUTOINCREMENT FROM DATABASE
+		// REUSE MODE: transaction
+		// adTestOne.id = VALUE, AUTOINCREMENT FROM DATABASE
+		
+		// What is good about REUSE? When running this code in some transaction (using @Transactional)
+		// the PreparedStatement being used for INSERT can be reused in the next INSERT (some lines below)
+		// As always there is a cache ONLY for DMLs where the key is the statement. If the statement is the same
+		// the PreparedStatement can be reused. Reusing some PreparedStatement means there is no need to call again
+		// getConnection saving in this way CPU cycles. Besides when running in some transaction getConnection
+		// will always return the same connection so, again calling getConnection is not needed.
+		// If there is no transaction the cache is useless because after every DML will be cleaned up. Without transaction
+		// REUSE and SIMPLE are the same. With transaction REUSE skips the code calling getConnection. With transaction
+		// getConnection returns always the same connection. So, with transaction we can avoid some CPU cycles using REUSE.
 
 		final Ad adTestTwo = new Ad();
 		adTestTwo.setAdMobileImage("bildTwo.jpg");