From de4c356189ec3747124e9b4fd81dd37ce1d8a21d Mon Sep 17 00:00:00 2001
From: Guillaume Smet <guillaume.smet@gmail.com>
Date: Thu, 19 Jul 2018 13:31:37 +0200
Subject: [PATCH] HHH-12827 Define a numeric type as decimal for DB2

DB2 converts the numeric type to decimal and returns Types.DECIMAL for a
numeric. We change the type name used so that we have a match when
comparing the type names as last resort.
---
 .../org/hibernate/dialect/DB2Dialect.java     | 25 ++++++++++++++-----
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java b/hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java
index 7e3ea78b57..13a84cee85 100644
--- a/hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java
+++ b/hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java
@@ -40,6 +40,7 @@ import org.hibernate.internal.CoreLogging;
 import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.internal.util.JdbcExceptionHelper;
 import org.hibernate.type.StandardBasicTypes;
+import org.hibernate.type.descriptor.sql.DecimalTypeDescriptor;
 import org.hibernate.type.descriptor.sql.SmallIntTypeDescriptor;
 import org.hibernate.type.descriptor.sql.SqlTypeDescriptor;
 
@@ -100,7 +101,12 @@ public class DB2Dialect extends Dialect {
 		registerColumnType( Types.TIME, "time" );
 		registerColumnType( Types.TIMESTAMP, "timestamp" );
 		registerColumnType( Types.VARBINARY, "varchar($l) for bit data" );
-		registerColumnType( Types.NUMERIC, "numeric($p,$s)" );
+		// DB2 converts numeric to decimal under the hood
+		// Note that the type returned by DB2 for a numeric column will be Types.DECIMAL. Thus, we have an issue when
+		// comparing the types during the schema validation, defining the type to decimal here as the type names will
+		// also be compared and there will be a match. See HHH-12827 for the details.
+		registerColumnType( Types.NUMERIC, "decimal($p,$s)" );
+		registerColumnType( Types.DECIMAL, "decimal($p,$s)" );
 		registerColumnType( Types.BLOB, "blob($l)" );
 		registerColumnType( Types.CLOB, "clob($l)" );
 		registerColumnType( Types.LONGVARCHAR, "long varchar" );
@@ -210,7 +216,7 @@ public class DB2Dialect extends Dialect {
 		registerKeyword( "only" );
 
 		getDefaultProperties().setProperty( Environment.STATEMENT_BATCH_SIZE, NO_BATCH );
-		
+
 		uniqueDelegate = new DB2UniqueDelegate( this );
 	}
 
@@ -365,7 +371,7 @@ public class DB2Dialect extends Dialect {
 	@Override
 	public ResultSet getResultSet(CallableStatement ps) throws SQLException {
 		boolean isResultSet = ps.execute();
-		// This assumes you will want to ignore any update counts 
+		// This assumes you will want to ignore any update counts
 		while ( !isResultSet && ps.getUpdateCount() != -1 ) {
 			isResultSet = ps.getMoreResults();
 		}
@@ -478,7 +484,14 @@ public class DB2Dialect extends Dialect {
 
 	@Override
 	protected SqlTypeDescriptor getSqlTypeDescriptorOverride(int sqlCode) {
-		return sqlCode == Types.BOOLEAN ? SmallIntTypeDescriptor.INSTANCE : super.getSqlTypeDescriptorOverride( sqlCode );
+		if ( sqlCode == Types.BOOLEAN ) {
+			return SmallIntTypeDescriptor.INSTANCE;
+		}
+		else if ( sqlCode == Types.NUMERIC ) {
+			return DecimalTypeDescriptor.INSTANCE;
+		}
+
+		return super.getSqlTypeDescriptorOverride( sqlCode );
 	}
 
 	@Override
@@ -496,12 +509,12 @@ public class DB2Dialect extends Dialect {
 			}
 		};
 	}
-	
+
 	@Override
 	public UniqueDelegate getUniqueDelegate() {
 		return uniqueDelegate;
 	}
-	
+
 	@Override
 	public String getNotExpression( String expression ) {
 		return "not (" + expression + ")";