Switch to IEEE binary floats by default on Oracle

Author: beikov

hibernate-core/src/main/java/org/hibernate/cfg/DialectSpecificSettings.java

@@ -36,6 +36,15 @@ public interface DialectSpecificSettings {
 	 */
 	String ORACLE_APPLICATION_CONTINUITY = "hibernate.dialect.oracle.application_continuity";
 
+	/**
+	 * Specifies whether the dialect should use the IEEE Oracle SQL types {@code binary_float}/{@code binary_double}
+	 * over {@code float(p)}/{@code real}/{@code double precision} when generating DDL or SQL casts for float types.
+	 *
+	 * @settingDefault {@code true}
+	 * @since 7.0
+	 */
+	String ORACLE_USE_IEEE_FLOATS = "hibernate.dialect.oracle.use_ieee_floats";
+
 	/**
 	 * Specifies whether this database's {@code ansinull} setting is enabled.
 	 *

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

@@ -91,6 +91,7 @@
 import org.hibernate.type.descriptor.jdbc.SqlTypedJdbcType;
 import org.hibernate.type.descriptor.jdbc.spi.JdbcTypeRegistry;
 import org.hibernate.type.descriptor.sql.internal.ArrayDdlTypeImpl;
+import org.hibernate.type.descriptor.sql.internal.CapacityDependentDdlType;
 import org.hibernate.type.descriptor.sql.internal.DdlTypeImpl;
 import org.hibernate.type.descriptor.sql.internal.NamedNativeEnumDdlTypeImpl;
 import org.hibernate.type.descriptor.sql.internal.NamedNativeOrdinalEnumDdlTypeImpl;
@@ -107,6 +108,7 @@
 import static org.hibernate.cfg.AvailableSettings.BATCH_VERSIONED_DATA;
 import static org.hibernate.cfg.DialectSpecificSettings.ORACLE_EXTENDED_STRING_SIZE;
 import static org.hibernate.cfg.DialectSpecificSettings.ORACLE_AUTONOMOUS_DATABASE;
+import static org.hibernate.cfg.DialectSpecificSettings.ORACLE_USE_IEEE_FLOATS;
 import static org.hibernate.dialect.OracleJdbcHelper.getArrayJdbcTypeConstructor;
 import static org.hibernate.dialect.OracleJdbcHelper.getNestedTableJdbcTypeConstructor;
 import static org.hibernate.exception.spi.TemplatedViolatedConstraintNameExtractor.extractUsingTemplate;
@@ -993,11 +995,21 @@ public void contributeTypes(TypeContributions typeContributions, ServiceRegistry
 			typeContributions.contributeJdbcType( OracleReflectionStructJdbcType.INSTANCE );
 		}
 
+		final ConfigurationService configurationService = serviceRegistry.requireService( ConfigurationService.class );
 		// account for Oracle's deprecated support for LONGVARBINARY
 		// prefer BLOB, unless the user explicitly opts out
-		final boolean preferLong = serviceRegistry.requireService( ConfigurationService.class )
-				.getSetting( PREFER_LONG_RAW, StandardConverters.BOOLEAN, false );
+		final boolean preferLong =
+				configurationService.getSetting( PREFER_LONG_RAW, StandardConverters.BOOLEAN, false );
+		final boolean preferIeeeFloats =
+				configurationService.getSetting( ORACLE_USE_IEEE_FLOATS, StandardConverters.BOOLEAN, true );
 		typeContributions.contributeJdbcType( preferLong ? BlobJdbcType.PRIMITIVE_ARRAY_BINDING : BlobJdbcType.DEFAULT );
+		if ( preferIeeeFloats ) {
+			typeContributions.getTypeConfiguration().getDdlTypeRegistry().addDescriptor(
+					CapacityDependentDdlType.builder( FLOAT, columnType( DOUBLE ), this )
+							.withTypeCapacity( getFloatPrecision(), columnType( REAL ) )
+							.build()
+			);
+		}
 
 		if ( getVersion().isSameOrAfter( 21 ) ) {
 			typeContributions.contributeJdbcType( OracleJsonJdbcType.INSTANCE );

hibernate-core/src/test/java/org/hibernate/orm/test/hql/ASTParserLoadingTest.java

@@ -6,6 +6,8 @@
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
+import java.math.MathContext;
+import java.math.RoundingMode;
 import java.sql.Time;
 import java.sql.Timestamp;
 import java.util.ArrayList;
@@ -2825,12 +2827,8 @@ public void testStr() {
 		an.setBodyWeight(123.45f);
 		session.persist( an );
 		String str = (String) session.createQuery("select str(an.bodyWeight) from Animal an where str(an.bodyWeight) like '%1%'").uniqueResult();
-		if ( getDialect() instanceof DB2Dialect ) {
-			assertTrue( str.startsWith( "1.234" ) );
-		}
-		else {
-			assertTrue( str.startsWith("123.4") );
-		}
+		BigDecimal value = new BigDecimal( str, new MathContext( 4, RoundingMode.DOWN ) );
+		assertEquals( new BigDecimal( "123.4" ), value );
 
 		String dateStr1 = (String) session.createQuery("select str(current_date) from Animal").uniqueResult();
 		String dateStr2 = (String) session.createQuery("select str(year(current_date))||'-'||str(month(current_date))||'-'||str(day(current_date)) from Animal").uniqueResult();

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/embeddable/JsonWithArrayEmbeddableTest.java

@@ -20,6 +20,7 @@
 
 import org.hibernate.annotations.JdbcTypeCode;
 import org.hibernate.cfg.AvailableSettings;
+import org.hibernate.cfg.DialectSpecificSettings;
 import org.hibernate.dialect.OracleDialect;
 
 import org.hibernate.testing.orm.junit.SkipForDialect;
@@ -55,7 +56,11 @@
 		integrators = SharedDriverManagerTypeCacheClearingIntegrator.class
 )
 // Don't reorder columns in the types here to avoid the need to rewrite the test
-@ServiceRegistry(settings = @Setting(name = AvailableSettings.COLUMN_ORDERING_STRATEGY, value = "legacy"))
+@ServiceRegistry(settings = {
+		@Setting(name = AvailableSettings.COLUMN_ORDERING_STRATEGY, value = "legacy"),
+		// Avoids running into Oracle bugs when converting a JSON float array to varray of binary_double
+		@Setting(name = DialectSpecificSettings.ORACLE_USE_IEEE_FLOATS, value = "false")
+})
 @DomainModel(annotatedClasses = JsonWithArrayEmbeddableTest.JsonHolder.class)
 @SessionFactory
 public class JsonWithArrayEmbeddableTest {

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/formula/FormulaTests.java

@@ -114,7 +114,7 @@ public static class Account {
 		@DialectOverride.Formula(dialect = DB2Dialect.class,
 				override = @Formula("varchar_format(rate * 100) || '%'"))
 		@DialectOverride.Formula(dialect = OracleDialect.class,
-				override = @Formula("to_char(rate * 100) || '%'"))
+				override = @Formula("to_char(cast(rate * 100 as number(10,2))) || '%'"))
 		@DialectOverride.Formula(dialect = SQLServerDialect.class,
 				override = @Formula("ltrim(str(rate * 100, 10, 2)) + '%'"))
 		@DialectOverride.Formula(dialect = SybaseDialect.class,

migration-guide.adoc

@@ -310,6 +310,26 @@ The migration requires to read data and re-save it.
 
 To retain backwards compatibility, configure the setting `hibernate.type.preferred_array_jdbc_type` to `VARBINARY`.
 
+[[float-mapping-changes-oracle]]
+== DDL type for Java `float` and `double` changed on Oracle
+
+Previous version of Hibernate ORM mapped Java `float` and `double` to Oracle `float(p)`, `real` or `double precision`
+types, which are all internally implemented as `number`. To avoid potential misbehavior compared to Java execution
+and match the expectations of the IEEE floating point semantics as requested by using Java `float`/`double`,
+the default DDL types were changed to Oracles IEEE floating point types `binary_float` and `binary_double` respectively.
+
+Migration requires multiple steps because Oracle doesn't support online type changes:
+
+```sql
+alter table TBL add (NEW_COLUMN binary_float);
+update TBL set NEW_COLUMN=OLD_COLUMN;
+alter table TBL drop column OLD_COLUMN;
+alter table TBL rename column NEW_COLUMN to OLD_COLUMN;
+```
+
+Note that changing the schema is not required for Hibernate ORM to work correctly.
+The previous behavior may be recovered by setting `hibernate.dialect.oracle.use_ieee_floats` to `false`.
+
 [[sf-name]]
 == SessionFactory Name (and JNDI)