HHH-15958 support the @RowId annotation on DB2 LUW

... and perhaps also on DB2 for z and i (no way to test it)

hibernate-core/src/main/java/org/hibernate/annotations/RowId.java

@@ -13,25 +13,35 @@ import static java.lang.annotation.ElementType.TYPE;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
 /**
- * Specifies that an Oracle-style {@code rowid} should be used in SQL
- * {@code update} statements for an entity, instead of the primary key.
+ * Specifies that a {@code rowid}-like column or pseudo-column should be
+ * used as the row locator in SQL {@code update} statements for an entity,
+ * instead of the primary key of the table.
  * <p>
  * If the {@linkplain org.hibernate.dialect.Dialect SQL dialect} does
- * not support some sort of {@code rowid}, this annotation is ignored.
+ * not support some sort of {@code rowid}-like column or pseudo-column,
+ * then this annotation is ignored, and the primary key is used as the
+ * row locator.
  *
  * @author Steve Ebersole
+ *
+ * @see org.hibernate.dialect.Dialect#rowId
  */
 @Target(TYPE)
 @Retention(RUNTIME)
 public @interface RowId {
 	/**
-	 * Specifies the {@code rowid} identifier.
+	 * Specifies the name of the {@code rowid}-like column for databases
+	 * where the column is declared explicitly in DDL.
 	 * <p>
-	 * For example, on Oracle, this should be just {@code "rowid"}.
+	 * It is <em>not</em> necessary to specify the name for databases where
+	 * the {@code rowid}-like value is an implicitly-existing pseudo-column,
+	 * and on those databases, this annotation member is ignored.
 	 *
-	 * @deprecated the {@code rowid} identifier is now inferred
-	 * automatically from the {@link org.hibernate.dialect.Dialect}
+	 * @apiNote Previously, this annotation member was required. But the
+	 *          name of the column it is now usually determined by calling
+	 *          {@link org.hibernate.dialect.Dialect#rowId}, and so this
+	 *          member is now usually ignored. The exception is for certain
+	 *          flavors of DB2.
 	 */
-	@Deprecated(since = "6.2")
 	String value() default "";
 }

hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java

@@ -948,8 +948,8 @@ public class DB2Dialect extends Dialect {
 	@Override
 	public IdentifierHelper buildIdentifierHelper(IdentifierHelperBuilder builder, DatabaseMetaData dbMetaData)
 			throws SQLException {
-		builder.setAutoQuoteInitialUnderscore(true);
-		return super.buildIdentifierHelper(builder, dbMetaData);
+		builder.setAutoQuoteInitialUnderscore( true );
+		return super.buildIdentifierHelper( builder, dbMetaData );
 	}
 
 	@Override
@@ -976,4 +976,20 @@ public class DB2Dialect extends Dialect {
 	public String getCreateUserDefinedTypeExtensionsString() {
 		return " instantiable mode db2sql";
 	}
+
+	/**
+	 * The more "standard" syntax is {@code rid_bit(alias)} but here we use {@code alias.rowid}.
+	 * <p>
+	 * There is also an alternative {@code rid()} of type {@code bigint}, but it cannot be used
+	 * with partitioning.
+	 */
+	@Override
+	public String rowId(String rowId) {
+		return "rowid";
+	}
+
+	@Override
+	public int rowIdSqlType() {
+		return VARBINARY;
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/DB2iDialect.java

@@ -28,8 +28,10 @@ import org.hibernate.sql.exec.spi.JdbcOperation;
 
 import java.util.List;
 
+import static org.hibernate.type.SqlTypes.ROWID;
+
 /**
- * A SQL dialect for DB2 for iSeries version 7.1 and above, previously known as "DB2/400".
+ * A SQL dialect for DB2 for IBM i version 7.1 and above, previously known as "DB2/400".
  *
  * @author Peter DeGregorio (pdegregorio)
  * @author Christian Beikov
@@ -149,4 +151,23 @@ public class DB2iDialect extends DB2Dialect {
 			}
 		};
 	}
+
+	// I speculate that this is a correct implementation of rowids for DB2 for i,
+	// just on the basis of the DB2 docs, but I currently have no way to test it
+	// Note that the implementation inherited from DB2Dialect for LUW will not work!
+
+	@Override
+	public String rowId(String rowId) {
+		return rowId.isEmpty() ? "rowid_" : rowId;
+	}
+
+	@Override
+	public int rowIdSqlType() {
+		return ROWID;
+	}
+
+	@Override
+	public String getRowIdColumnString(String rowId) {
+		return rowId( rowId ) + " rowid not null generated always";
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/DB2zDialect.java

@@ -30,10 +30,11 @@ import jakarta.persistence.TemporalType;
 
 import java.util.List;
 
+import static org.hibernate.type.SqlTypes.ROWID;
 import static org.hibernate.type.SqlTypes.TIMESTAMP_WITH_TIMEZONE;
 
 /**
- * A SQL dialect for DB2 for z/OS version 12.1 and above, previously known as :
+ * A SQL dialect for DB2 for z/OS version 12.1 and above, previously known as:
  * <ul>
  * <li>"Db2 UDB for z/OS", and
  * <li>"Db2 UDB for z/OS and OS/390".
@@ -208,4 +209,23 @@ public class DB2zDialect extends DB2Dialect {
 			}
 		};
 	}
+
+	// I speculate that this is a correct implementation of rowids for DB2 for z/OS,
+	// just on the basis of the DB2 docs, but I currently have no way to test it
+	// Note that the implementation inherited from DB2Dialect for LUW will not work!
+
+	@Override
+	public String rowId(String rowId) {
+		return rowId.isEmpty() ? "rowid_" : rowId;
+	}
+
+	@Override
+	public int rowIdSqlType() {
+		return ROWID;
+	}
+
+	@Override
+	public String getRowIdColumnString(String rowId) {
+		return rowId( rowId ) + " rowid not null generated always";
+	}
 }

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

@@ -4628,8 +4628,17 @@ public abstract class Dialect implements ConversionContext {
 	 * The name of a {@code rowid}-like pseudo-column which
 	 * acts as a high-performance row locator, or null if
 	 * this dialect has no such pseudo-column.
+	 * <p>
+	 * If the {@code rowid}-like value is an explicitly-declared
+	 * named column instead of an implicit pseudo-column, and if
+	 * the given name is nonempty, return the given name.
+	 *
+	 * @param rowId the name specified by
+	 *        {@link org.hibernate.annotations.RowId#value()},
+	 *        which is ignored if {@link #getRowIdColumnString}
+	 *        is not overridden
 	 */
-	public String rowId() {
+	public String rowId(String rowId) {
 		return null;
 	}
 
@@ -4642,4 +4651,15 @@ public abstract class Dialect implements ConversionContext {
 	public int rowIdSqlType() {
 		return ROWID;
 	}
+
+	/**
+	 * If this dialect requires that the {@code rowid} column be
+	 * declared explicitly, return the DDL column definition.
+	 *
+	 * @return the DDL column definition, or {@code null} if
+	 *         the {@code rowid} is an implicit pseudo-column
+	 */
+	public String getRowIdColumnString(String rowId) {
+		return null;
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/H2Dialect.java

@@ -859,7 +859,7 @@ public class H2Dialect extends Dialect {
 	}
 
 	@Override
-	public String rowId() {
+	public String rowId(String rowId) {
 		return "_rowid_";
 	}
 

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

@@ -1408,7 +1408,7 @@ public class OracleDialect extends Dialect {
 	}
 
 	@Override
-	public String rowId() {
+	public String rowId(String rowId) {
 		return "rowid";
 	}
 }

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

@@ -1350,7 +1350,7 @@ public class PostgreSQLDialect extends Dialect {
 	// (these would help if we used 'delete' instead of 'truncate')
 
 	@Override
-	public String rowId() {
+	public String rowId(String rowId) {
 		return "ctid";
 	}
 

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

@@ -15,7 +15,6 @@ import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.SqlAstTranslatorFactory;
-import org.hibernate.sql.ast.spi.SqlAppender;
 import org.hibernate.sql.ast.spi.StandardSqlAstTranslatorFactory;
 import org.hibernate.sql.ast.tree.Statement;
 import org.hibernate.sql.exec.spi.JdbcOperation;

hibernate-core/src/main/java/org/hibernate/persister/entity/AbstractEntityPersister.java

@@ -545,12 +545,7 @@ public abstract class AbstractEntityPersister
 		identifierAliases = new String[identifierColumnSpan];
 
 		final String rowId = persistentClass.getRootTable().getRowId();
-		if ( rowId == null ) {
-			rowIdName = null;
-		}
-		else {
-			rowIdName = rowId.isEmpty() ? dialect.rowId() : rowId;
-		}
+		rowIdName = rowId == null ? null : dialect.rowId( rowId );
 
 		if ( persistentClass.getLoaderName() != null ) {
 			// We must resolve the named query on-demand through the boot model because it isn't initialized yet

hibernate-core/src/main/java/org/hibernate/tool/schema/internal/StandardTableExporter.java

@@ -71,6 +71,12 @@ public class StandardTableExporter implements Exporter<Table> {
 				}
 				appendColumn( createTable, column, table, metadata, dialect, context );
 			}
+			if ( table.getRowId() != null ) {
+				String rowIdColumn = dialect.getRowIdColumnString( table.getRowId() );
+				if ( rowIdColumn != null ) {
+					createTable.append(", ").append( rowIdColumn );
+				}
+			}
 			if ( table.hasPrimaryKey() ) {
 				createTable.append( ", " ).append( table.getPrimaryKey().sqlConstraintString( dialect ) );
 			}

hibernate-core/src/test/java/org/hibernate/orm/test/rowid/RowIdTest.java

@@ -48,7 +48,7 @@ public class RowIdTest {
 	void testRowId(SessionFactoryScope scope) {
 		final String updatedName = "Smart phone";
 		scope.inTransaction( session -> {
-			String rowId = scope.getSessionFactory().getJdbcServices().getDialect().rowId();
+			String rowId = scope.getSessionFactory().getJdbcServices().getDialect().rowId("");
 
 			SQLStatementInspector statementInspector = (SQLStatementInspector) scope.getStatementInspector();
 			statementInspector.clear();

hibernate-testing/src/main/java/org/hibernate/testing/DialectChecks.java

@@ -314,7 +314,7 @@ abstract public class DialectChecks {
 	public static class SupportsRowId implements DialectCheck {
 		@Override
 		public boolean isMatch(Dialect dialect) {
-			return dialect.rowId() != null;
+			return dialect.rowId("") != null;
 		}
 	}
 }