HHH-18035 Change Oracle default timestamp precision to 9

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/OracleLegacyDialect.java

@@ -1229,6 +1229,12 @@ public class OracleLegacyDialect extends Dialect {
 		return getVersion().isSameOrAfter( 12, 2 ) ? 128 : 30;
 	}
 
+	@Override
+	public int getDefaultTimestampPrecision() {
+		// 9 is supported at least since v10
+		return getVersion().isSameOrAfter( 10 ) ? 9 : 6;
+	}
+
 	@Override
 	public CallableStatementSupport getCallableStatementSupport() {
 		// Oracle supports returning cursors

hibernate-core/src/main/java/org/hibernate/dialect/OracleDialect.java

@@ -1311,6 +1311,11 @@ public class OracleDialect extends Dialect {
 		return 128;
 	}
 
+	@Override
+	public int getDefaultTimestampPrecision() {
+		return 9;
+	}
+
 	@Override
 	public CallableStatementSupport getCallableStatementSupport() {
 		// Oracle supports returning cursors

migration-guide.adoc

@@ -131,6 +131,11 @@ String isDefault();
 * Removed `hibernate.mapping.precedence` and friends
 
 
+[[ddl-implicit-datatype-timestamp]]
+== Default precision for Oracle timestamp
+
+The default precision for Oracle timestamps was changed to 9 i.e. nanosecond precision.
+
 [[todo]]
 == Todos (dev)