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 (file)
--- 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");