5 Compatibility and Interoperability

The COMPATIBLE Initialization Parameter

Oracle Database enables you to control the compatibility of your database with the COMPATIBLE initialization parameter. By default, when the COMPATIBLE initialization parameter is not set in your parameter file, it defaults to 11.0.0 for Oracle Database 11g Release 1 (11.1). You cannot use new Oracle Database 11g Release 1 (11.1) features that would make your upgraded database incompatible unless the COMPATIBLE initialization parameter is set to this value.

Table 5-1 lists the default, minimum, and maximum values of the COMPATIBLE initialization parameter in Oracle Database 11g Release 1 (11.1) and in each release supported for upgrading to Oracle Database 11g Release 1 (11.1).

SQL> SELECT name, value, description FROM v$parameter
         WHERE name = 'compatible';

Setting the COMPATIBLE Initialization Parameter

Complete the following steps to set the COMPATIBLE initialization parameter to a higher value:

1. Perform a backup of your database before you raise the COMPATIBLE initialization parameter (optional).

   Raising the COMPATIBLE initialization parameter might cause your database to become incompatible with earlier releases of Oracle Database, and a backup ensures that you can return to the earlier release if necessary.

   See Also:

   Oracle Database Backup and Recovery User's Guide for more information about performing a backup

2. If you are using a server parameter file, then complete the following steps:

   1. Update the server parameter file to set or change the value of the COMPATIBLE initialization parameter.

      For example, to set the COMPATIBLE initialization parameter to 11.0.0, enter the following statement:

      SQL> ALTER SYSTEM SET COMPATIBLE = '11.0.0' SCOPE=SPFILE;
      
      

   2. Shut down and restart the instance.

   Note:

   When upgrading systems with HARD-compliant storage (Hardware Assisted Resilient Data), consider the following:

   • If the COMPATIBLE parameter is set to a release number earlier than 11.0.0, then you cannot locate the server parameter file (SPFILE) on HARD storage.

   • If the COMPATIBLE parameter is set to 11.0.0, then you can optionally locate the server parameter file on HARD storage.

   Because the default SPFILE location (ORACLE_HOME/dbs) might not be on a HARD-compliant storage system, it is likely you must provide a parameter file that specifies the location of the SPFILE.

   See Also:

   Oracle Database High Availability Overview or Oracle Database Concepts for more information on HARD storage

3. If you are using an initialization parameter file, then complete the following steps:

   1. Shut down the instance if it is running:

      SQL> SHUTDOWN IMMEDIATE
      
      

   2. Edit the initialization parameter file to set or change the value of the COMPATIBLE initialization parameter.

      For example, to set the COMPATIBLE initialization parameter to 11.0.0, enter the following in the initialization parameter file:

      COMPATIBLE = 11.0.0
      
      

   3. Start the instance using STARTUP.

Automatic Maintenance Tasks Management

Automatic Maintenance Tasks Management, a new database component in Oracle Database 11g Release 1 (11.1), schedules all automatic maintenance tasks in an expanded set of maintenance windows. Automatic Maintenance Tasks Management enables you to exercise finer control over maintenance task scheduling for tasks such as optimizer statistics gathering, Segment Advisor, and Automatic SQL Tuning Advisor.

Automatic Maintenance Tasks Management uses all existing maintenance windows (for example, windows that are current members of the MAINTENANCE_WINDOW_GROUP. Existing resource plans associated with the maintenance windows are used. However, AUTOTASK_CONSUMER_GROUP is replaced in the resource plans by the AutoTask Resource Subplan.

If you disable either Optimizer Statistics Gathering or Segment Advisor jobs in 10g, then the corresponding Automatic Maintenance Tasks Management feature is disabled after upgrading to Oracle Database 11g Release 1 (11.1).

The following list shows the default settings for maintenance tasks:

• Online backup is disabled

• Optimizer Statistics Gathering is on

• Segment Advisor is on

• Automatic SQL Tuning is off

All other Automatic Maintenance Tasks Management clients are enabled by default.

Although Automatic Maintenance Tasks Management is automatically enabled when upgrading to Oracle Database 11g Release 1 (11.1), AutoTask online backup is not enabled automatically. You must configure online backup manually, if desired, after upgrading the database. If you perform a database downgrade, then Automatic Maintenance Tasks Management reverts to the default behavior for that release.

New SYSASM Privilege and OSASM Group for ASM Administration

Oracle Database 11g Release 1 (11.1) introduces a new SYSASM privilege that is specifically intended for performing ASM administration tasks. Using the SYSASM privilege instead of the SYSDBA privilege provides a clearer division of responsibility between ASM administration and database administration.

Warning messages will appear in the ASM alert.log if SYSDBA performs disk group maintenance (CREATE DISKGROUP, MOUNT/DISMOUNT, ADD/DROP DISK, ONLINE/OFFLINE DISK, DROP DISKGROUP). These tasks are deprecated for SYSDBA; they should be performed by SYSASM.

OSASM is a new operating system (OS) group that is used exclusively for ASM. Members of the OSASM group can connect AS SYSASM using OS authentication and have full access to ASM.

This feature is described in more detail in "Upgrading a Database that Uses Automatic Storage Management (ASM)".

ASM Disk Group Compatibility

Beginning with Oracle Database 11g Release 1 (11.1), you can advance the Oracle Database and the ASM disk group compatibility settings across software versions. Using the new compatibility attributes, compatible.rdbms and compatible.asm, you can specify the minimum software version required to use the disk group for the database and the disk group for ASM, respectively.

This feature enables heterogeneous environments with disk groups from Oracle Database 10g Release 1 (10.1), Oracle Database 10g Release 2 (10.2), and Oracle Database 11g Release 1 (11.1). By default, both attributes are set to 10.1. You must advance these attributes to take advantage of the new features.

COMPUTE STATISTICS and ESTIMATE STATISTICS Clauses

In earlier releases, the ANALYZE...COMPUTE STATISTICS and ANALYZE...ESTIMATE STATISTICS clauses could be used to start or stop the collection of statistics on an index. These clauses have been made obsolete. Oracle Database 11g Release 1 (11.1) automatically collects statistics during index creation and rebuild. These clauses are no longer supported and using them causes errors.

Oracle Data Mining Models and the DMSYS Schema Objects

During the upgrade to Oracle Database 11g Release 1 (11.1), DMSYS schema objects along with user models residing in user schemas are upgraded from any previous release without major constraints. Upon completion of the upgrade, the mining metadata is migrated into the SYS schema while the user models continue functioning with the new metadata. Oracle recommends that you drop the DMSYS schema after setting the COMPATIBLE initialization parameter to 11.0.0. In addition, the DBA will need to grant the new CREATE MINING MODEL privilege so that existing users can continue to build mining models.

Data mining models residing in a user schema are automatically upgraded as part of the model upgrade, which is an integral part of the Oracle Database upgrade process. Data mining model Export and Import utilities can also be used as a means of upgrading data mining models from one release to another.

During the database downgrade process, the data mining component is downgraded to a previous release. The downgrade process reloads DMSYS objects such as packages, types, and table objects as well as downgrading model objects residing in user schemas (if any). Objects that were created as a part of the database upgrade are removed from the SYS schema during the downgrade procedure. The process is transparent and does not require any user intervention.

After upgrading (and dropping the DMSYS schema after setting the COMPATIBLE initialization parameter to 11.0.0), importing models that were exported from Oracle Database 10g Release 1 (10.1) might have some complications due to their reference to the now nonexistent DMSYS schema. To handle this case, Oracle provides scripts to sufficiently (and minimally) mimic the DMSYS interface present in the Oracle Database 10g Release 1 (10.1) database so that the Import process can proceed. This is not a common occurrence because models become stale over time and users typically want to rebuild their models rather than import older ones.

Note that Data Mining is not protected by the COMPATIBLE initialization parameter. If COMPATIBLE is set at 10.1.0 or 10.2.0 while the database has been upgraded to Oracle Database 11g Release 1 (11.1), then all new and existing Data Mining features and functions should work. If you have built new mining models that are only available in Oracle Database 11g Release 1 (11.1), and subsequently decide to downgrade the database to Oracle Database 10g Release 2 (10.2), you will be required to drop the new mining models before downgrading.

Oracle Data Mining Scoring Engine

Beginning with Oracle Database 11g Release 1 (11.1), the Oracle Data Mining Scoring Engine can no longer be installed.

SQL Plan Management and Control of SQL Plan Baselines

The use of stored outlines is deprecated in Oracle Database 11g Release 1 (11.1). Instead, you should use the SQL plan management feature that enables the optimizer to maintain a history of execution plans for a SQL statement. Using the execution plan history, the optimizer is able to detect a new plan representing a plan change for a SQL statement. When the optimizer detects a new plan, it stores the new plan and marks it for performance evaluation and uses the old (currently known good) plan. The optimizer uses the new plan only after its performance is verified to be better than that of the old plan. A SQL plan baseline consists of a set of known good plans for a SQL statement.

Migration of SQL Profiles

SQL Profiles are SQL management objects that were introduced in Oracle Database 10g Release 1 (10.1). These objects resided in a section of the dictionary that was defined in SYSTEM tablespace. The dictionary tables storing the SQL profiles are restructured to accommodate the storage of SQL plan baselines, which are also SQL management objects. Further, these dictionary tables are now defined in the SYSAUX tablespace.

When you upgrade from Oracle Database 10g Release 1 (10.1) to Oracle Database 11g Release 1 (11.1), the database upgrade script moves existing SQL profiles from the SYSTEM tablespace to the SYSAUX tablespace. Thus, if an Oracle Database 11g Release 1 (11.1) database instance is up but the SYSAUX tablespace is offline, then the optimizer is not able to access SQL Management objects, which can affect the performance on some of the SQL workload. In contrast, in Oracle Database 10g Release 1 (10.1), because SQL profiles were stored in SYSTEM tablespace, the unavailability of SQL profiles did not exist. Note that starting with Oracle Database 11g Release 1 (11.1), taking the SYSAUX tablespace offline can have potential SQL performance consequences.

Backward Compatibility

In Oracle Database 11g Release 1 (11.1):

• If a stored outline for a SQL statement is active for the user session (for example, the stored outline category matches with the user session category), then the statement is compiled using the stored outline.

• If a private outline is available for a SQL statement, then the statement is compiled using the private outline.

If a stored outline is available for a SQL statement, then the SQL Plan Management feature is not used. However, if another user session uses the same SQL statement but without an active stored outline, then the SQL plan management feature is used.

Binary XML Support for Oracle XML Database

The binary XML storage option that is new in Oracle Database 11g Release 1 (11.1) is available when the COMPATIBLE initialization parameter is set to 11.0.0 or higher. When you create a table or column with this storage option, the minimum compatibility requirement is checked. This also applies when storing binary XML documents directly in the XML DB repository.

PL/SQL Native Compilation and Access Control for Network Utility Packages

The following sections describe compatibility and interoperability changes introduced in PL/SQL for Oracle Database 11g Release 1 (11.1).

PL/SQL Control Parameters

The behavior of some of the Oracle parameters which control the behavior of PL/SQL changes in Oracle Database 11g Release 1 (11.1):

• If PL/SQL debug code generation mode is selected by any parameter setup, then native code generation is turned off.

• Debug code generation is on if the PLSQL_OPTIMIZE_LEVEL <= 1.

• PLSQL_DEBUG is deprecated.

  You should use PLSQL_OPTIMIZE_LEVEL instead. A deprecation warning is issued if PLSQL_DEBUG is used.

• If PLSQL_OPTIMIZE_LEVEL <= 1, then native code generation is turned off.

• PLSQL_COMPILER_FLAGS is obsolete. It has no effect any longer and draws an error message that an illegal option is being set.

• PLSQL_V2_COMPATIBILITY is deprecated.

Change in WebDAV ACL Evaluation Rules in Oracle XML DB

Oracle XML DB uses a security mechanism that is based on access-control lists (ACLs) to restrict access to any Oracle XML DB resource. An ACL is a list of access-control entries (ACEs) that determine which users, roles, and groups have access to a given resource.

There have been changes to the treatment of WebDAV ACL entries. Prior to Oracle Database 11g Release 1 (11.1), a <deny> entry always trumped any <allow> entry in a given ACL. Beginning with Oracle Database 11g Release 1 (11.1), ACE order is irrelevant. The default behavior is determined only by the first <allow> or <deny> entry that is encountered. That is, the first entry determines the behavior for that principal and additional ACEs for that principal have no effect.

This change in the default behavior is different from, and is incompatible with, previous versions of Oracle Database. When upgrading to Oracle Database 11g Release 1 (11.1), you can get the same behavior as in previous releases by manually reordering the ACLs (if necessary). That is, if there are any ACLs that have <allow> followed somewhere by <deny>, then you should (manually) reorder the ACLs so that the <deny> entry occurs first.

Summary Management and SQL Access Advisor

Starting with Oracle Database 10g Release 2 (10.2), the DBMS_OLAP package, which is the Summary Advisor in Summary Management, is being deprecated and has been replaced by the SQL Access Advisor.

SQL Access Advisor Tasks

Due to internal structural changes to the SQL Access Advisor repository, a database upgrade resets all existing SQL Access Advisor tasks to their initial state. This effectively deletes all recommendation information for tasks that have successfully executed prior to upgrade.

After upgrade, the recommendation information can be restored by reexecuting the existing SQL Access Advisor tasks.

Standard Edition Starter Database

When the Standard Edition (SE) starter database is upgraded, the following components cannot be upgraded by the SE server because they require options that are not installed in the Standard Edition:

• OLAP Catalog

• OLAP Analytic Workspace

• Oracle OLAP API

After the upgrade, these components have a STATUS value of 'OPTION OFF' in the DBA_REGISTRY view, and there will be some invalid objects in the associated component schemas. The Database Upgrade Assistant (DBUA) shows unsuccessful upgrades for these components.

Core Dump Location

On UNIX systems, when an application program crashes due to an unhandled signal, such as segmentation fault, a core file is usually generated. The system default for that core file name is core located in the directory in which the application is currently running. Beginning with Oracle Database 11g Release 1 (11.1), applications using the Oracle Call Interface (OCI) can create a subdirectory named ora_core_process_id, where process_id is the UNIX ID of the process that crashed. The core file is then placed in that subdirectory instead.

LOG_ARCHIVE_DEST_n Parameter

Beginning with Oracle Database 11g Release 1 (11.1), the LOG_ARCHIVE_DEST_n parameter can be used to specify a local archiving destination on a database instance running Oracle Standard Edition. Previously, this parameter could only be specified on a database instance running Oracle Enterprise Edition.

SHARED_POOL_SIZE Parameter

The amount of shared pool memory allocated by Oracle Database releases before Oracle Database 10g Release 1 (10.1) was equal to the sum of the value of the SHARED_POOL_SIZE initialization parameter and the internal SGA overhead computed during instance startup. This overhead was based on the values of several other initialization parameters.

For example, if the SHARED_POOL_SIZE parameter is 64 megabytes and the internal SGA overhead is 12 megabytes, then the real size of shared pool in the SGA would be 76 megabytes, although the value of the SHARED_POOL_SIZE parameter would still be displayed as megabytes.

Starting with Oracle Database 10g Release 1 (10.1), the size of internal SGA overhead is included in the value of the SHARED_POOL_SIZE parameter. The shared pool memory allocated at startup is exactly the value of SHARED_POOL_SIZE. Therefore, this parameter must be set such that it includes both the internal SGA overhead and the desired effective value of the shared pool size.

Assuming that the internal SGA overhead remains unchanged, the effective available value of shared pool after startup would be 12 megabytes less than the value of the SHARED_POOL_SIZE parameter, or 52 megabytes. To maintain 64 megabytes for the effective value of shared pool memory, set the parameter to 76 megabytes.

Migration utilities for this release recommend new values for SHARED_POOL_SIZE based on the value of internal SGA overheads in the pre-upgrade environment, which you can determine by running the following query before upgrading to Oracle Database 11g Release 1 (11.1):

SQL> SELECT SUM(BYTES) FROM v$sgastat WHERE pool = 'shared pool';

In Oracle Database 11g Release 1 (11.1), the exact value of internal SGA overhead, or Startup overhead in Shared Pool, is listed in the new v$sgainfo view.

In manual SGA mode, values of SHARED_POOL_SIZE that are too small to accommodate the internal SGA overhead result in an ORA-00371 error during startup. This generated error message includes a suggested value for the SHARED_POOL_SIZE parameter. If you are using automatic shared memory management, the size of the shared pool is tuned automatically, and the ORA-00371 error is never generated.

JOB_QUEUE_PROCESSES Parameter

Beginning with Oracle Database 11g Release 1 (11.1), JOB_QUEUE_PROCESSES has changed from a basic to a non-basic initialization parameter. Most databases should be required to have only basic parameters set to run properly and efficiently.

In earlier Oracle Database releases, DBMS_JOB and DBMS_SCHEDULER shared the same job coordinator, and its behavior was controlled by the JOB_QUEUE_PROCESSES parameter. Now DBMS_JOB and DBMS_SCHEDULER work without setting this initialization parameter. You can still set it if you want, but you are no longer required to set it.

The range of supported values for JOB_QUEUE_PROCESSES is still 0-1000. If it is set to 0, then DBMS_SCHEDULER jobs run, and DBMS_JOB jobs do not run. The number of slave processes created for DBMS_SCHEDULER jobs is autotuned based on the load of the computer.

If JOB_QUEUE_PROCESSES is set to a value in the range of 1-1000, then both DBMS_JOB jobs and DBMS_SCHEDULER jobs run, and the number of slave processes created for these jobs is autotuned with an additional restriction that the total number of slave processes is capped at the value of JOB_QUEUE_PROCESSES.

SQL

The behavior of date formats has changed when used with XML functions. The XML Schema standard specifies that dates and timestamps in XML data be in standard formats. Prior to Oracle Database 10g Release 2 (10.2), dates and timestamps in XML data did not follow this standard; rather, the format of dates and timestamps in generated XML was determined by the database format.

As of Oracle Database 10g Release 2 (10.2), the XML generation functions in Oracle XML DB produce dates and timestamps according to the XML schema standard.

CONNECT Role

After upgrading to Oracle Database 10g Release 2 (10.2), the CONNECT role has only the CREATE SESSION privilege; the other privileges granted to the CONNECT role in earlier releases are revoked during the upgrade. For further information about this, see "Deprecated CONNECT Role".

Time Zone Files

The time zone files that are supplied with Oracle Database 10g Release 2 (10.2) have been updated from version 1 to version 2 to reflect changes in transition rules for some time zone regions. The changes might affect existing data of TIMESTAMP WITH TIME ZONE data type. For further information about this, see "TIMESTAMP WITH TIME ZONE Data Type".

New Limit for FAILED_LOGIN_ATTEMPTS

As of Oracle Database 10g Release 2 (10.2), the limit for FAILED_LOGIN_ATTEMPTS for the DEFAULT profile is 10. Prior to Oracle Database 10g Release 2 (10.2), the default was UNLIMITED.

SQL Optimizer

This section describes compatibility and interoperability issues relating to the SQL Optimizer in Oracle Database 10g Release 1 (10.1).

SQL

Starting with Oracle Database 10g Release 1 (10.1), CLOB <-> NCLOB implicit conversion in SQL and PL/SQL is allowed.

Starting with Oracle Database 10g Release 1 (10.1), name resolution for synonyms has changed. If the base object of a synonym does not exist, then the SQL compiler now tries looking up PUBLIC.base_object.

Starting with Oracle Database 10g Release 1 (10.1), VPD policies are attached to synonyms rather than the base objects.

Invalid Synonyms After an Upgrade

Starting with Oracle Database 10g Release 1 (10.1), if a synonym (public or private) is pointing to an object that does not exist or is invalid, then the synonym is invalid after the upgrade.

Manageability

Database performance statistics are now automatically collected by the Automatic Workload Repository (AWR) database component for databases upgraded to Oracle Database 10g Release 1 (10.1) and for newly created Oracle Database 10g Release 1 (10.1) databases. This data is stored in the SYSAUX tablespace, and is used by the database for automatic generation of performance recommendations.

If you currently use Statspack for performance data gathering, then refer to the Statspack README (spdoc.txt, located in the ORACLE_HOME/rdbms/admin directory) for directions on using Statspack in Oracle Database 10g Release 1 (10.1) to avoid conflict with the AWR.

Transaction and Space

Starting with Oracle Database 10g Release 1 (10.1), dropped objects are now moved to the recycle bin where the space is only reused when it is needed. This allows an object to be undropped using the FLASHBACK DROP feature.

Starting with Oracle Database 10g Release 1 (10.1), automatic tuning of undo retention is enabled by default. The UNDO_SUPPRESS_ERRORS initialization parameter has been deprecated. Errors generated when executing rollback segment operations while in automatic undo management mode are always suppressed.

Starting with Oracle Database 10g Release 1 (10.1), the default AUTOEXTEND NEXT size is larger for Oracle managed files (OMF).

Recovery and Data Guard

Starting with Oracle Database 10g Release 1 (10.1), the LOG_ARCHIVE_START initialization parameter has been deprecated. Archiving is now automatically started when the database is placed in ARCHIVELOG mode.

Starting with Oracle Database 10g Release 1 (10.1), the LOG_PARALLELISM initialization parameter has been deprecated. Log file parallelism is now automatically enabled.

Starting with Oracle Database 10g Release 1 (10.1), the default value for the RECOVERY_PARALLELISM initialization parameter now defaults to allow parallel recovery.

Starting with Oracle Database 10g Release 1 (10.1), the default value for the parallel clause in the ALTER DATABASE RECOVER DATABASE statement has changed to PARALLEL.

Starting with Oracle Database 10g Release 1 (10.1), the default buffer size for the ASYNC attribute of the LOG_ARCHIVE_DEST_n initialization parameter has increased from 2,048 blocks to 61,440 blocks.

Starting with Oracle Database 10g Release 1 (10.1), the default values of the parameters MAX_SGA and MAX_SERVERS as set by the DBMS_LOGSTDBY.APPLY_SET() procedure have changed.

Starting with Oracle Database 10g Release 1 (10.1), the default values for the Data Guard broker properties ApplyParallel, AsyncBlocks, and LogXptMode have changed.

Starting with Oracle Database 10g Release 1 (10.1), the default behavior of the STARTUP SQL*Plus command and the ALTER DATABASE MOUNT and ALTER DATABASE OPEN SQL statements have changed for physical standby databases. The commands now automatically detect that the database is a physical standby and thus the STANDBY DATABASE and READ ONLY options are made default.

RMAN

Starting with Oracle Database 10g Release 1 (10.1), RMAN now creates an empty file when restoring a file from backup and no backup of the file exists. RMAN backup of archived logs now automatically backs up logs that were created before the last resetlogs. Such logs were previously ignored.

Starting with Oracle Database 10g Release 1 (10.1), RMAN now continues to run the remaining portions of a backup or restore job when it encounters an error. RMAN now tries to restore from an alternate backup if it finds the targeted backup is corrupt.

CREATE DATABASE

In Oracle Database 10g Release 1 (10.1), a SYSAUX tablespace is always created at database creation time or whenever a database is upgraded. The SYSAUX tablespace serves as an auxiliary tablespace to the SYSTEM tablespace. Because SYSAUX is the default tablespace for many Oracle features and products that previously required their own tablespaces, it reduces the number of tablespaces that a DBA must maintain.

Starting with Oracle Database 10g Release 1 (10.1), the minimum and default log file sizes have increased. The minimum size is now 4 MB. The default size is 50 MB, unless using Oracle managed files (OMF) in which case the default is 100 MB.

Oracle Real Application Clusters

In Oracle Database 10g Release 1 (10.1), there is an automated high availability (HA) framework for Oracle Real Application Clusters. The framework provides detection, recovery, restart, and notification services.

Materialized Views

Starting with Oracle Database 10g Release 1 (10.1), some privilege name changes have been made. The new names appear in all data dictionary views, but both the old and new names are accepted by the GRANT and REVOKE SQL statements.

• CREATE SNAPSHOT changed to CREATE MATERIALIZED VIEW

• CREATE ANY SNAPSHOT changed to CREATE ANY MATERIALIZED VIEW

• ALTER ANY SNAPSHOT changed to ALTER ANY MATERIALIZED VIEW

• DROP ANY SNAPSHOT changed to DROP ANY MATERIALIZED VIEW

Change Data Capture

Starting with Oracle Database 10g Release 1 (10.1), the interfaces in DBMS_CDC_SUBSCRIBE and DBMS_CDC_PUBLISH now take a subscription name parameter instead of a subscription handle.

Starting with Oracle Database 10g Release 1 (10.1), subscriber views are now managed automatically. There is no longer any requirement to call the DBMS_CDC_SUBSCRIBE and DBMS_CDC_PUBLISH interfaces PREPARE_SUBSCRIBER_VIEW() and DROP_SUBSCRIBER_VIEW().

Starting with Oracle Database 10g Release 1 (10.1), the computation of synchronous Change Data Capture's RSID$ column has been changed to facilitate joining a subscriber view to itself in order to show both old and new values in the same row. The RSID$ values for the UO and UN rows associated with the same update operation are now the same. To revert to the Oracle9i behavior where UN RSID$ value is UO RSID$ value + 1 for the same update operation, set event 10983 to level 4.

Change in the Default Archival Processing to Remote Archive Destinations

Starting with Oracle Database 10g Release 1 (10.1), the default archival processing to remote destinations has changed so that archiver processes on the primary database completely and successfully archive the local online redo log files before transmitting the redo data to remote standby destinations. This default behavior is equivalent to setting the LOG_ARCHIVE_LOCAL_FIRST initialization parameter to true, which is also new in Oracle Database 10g Release 1 (10.1). Note that this new default archival processing is relevant only when log transport services are defined to use archiver processes (ARCn), not the log writer process (LGWR), when the archiver processes are writing to remote destinations, and when the remote standby destination is not a mandatory destination.

Prior to Oracle Database 10g Release 1 (10.1), the default behavior was to transmit redo data to the standby destination at the same time the online redo log file was being archived to the local online redo log files. You can achieve this behavior by setting the LOG_ARCHIVE_LOCAL_FIRST initialization parameter to false. This archival processing is also relevant only when log transport services are defined to use archiver processes (ARCn), not the log writer process (LGWR), when the archiver processes are writing to remote destinations, and when the remote standby destination is not a mandatory destination.

The benefit of the new default behavior is that local archiving, and hence, processing on the primary database, are not affected by archival to non-mandatory, remote destinations. Because local archiving is now disassociated with remote archiving, sites that might have policies to delete archived redo log files on the primary database immediately after backing them up must make sure that the standby destinations have received the corresponding redo data before deleting the archived redo log files on the primary database. You can query the V$ARCHIVED_LOG view to verify that the redo data has been received on standby destinations.

Limitations on NCHAR Data Types

In Oracle Database 10g Release 1 (10.1), the NCHAR data types such as NCHAR, NVARCHAR2, and NCLOB, are limited to the Unicode character set encoding, UTF8 and AL16UTF16.

PL/SQL Native Compilation

Starting with Oracle Database 10g Release 1 (10.1), the configuration of initialization parameters and the command setup for native compilation has been simplified. The important parameters now are PLSQL_NATIVE_LIBRARY_DIR and PLSQL_NATIVE_LIBRARY_SUBDIR_COUNT. The parameters related to the compiler, linker, and make utility have been obsoleted. Native compilation is turned on and off by a separate initialization parameter, PLSQL_CODE_TYPE, rather than being one of several options in the PLSQL_COMPILER_FLAGS parameter, which is now deprecated. The spnc_commands file, located in the ORACLE_HOME/plsql directory, contains the commands and options for compiling and linking, rather than a makefile.

Evaluation of Numeric Literals

Evaluation of numeric literals has changed such that at least one of the constants in a numeric computation with literals must be a decimal specified to the 10th place. This is because releases after Oracle Database 10g Release 1 (10.1) use INTEGER arithmetic (approximately 9 significant digits) for some expressions whereas Oracle Database9i Release 2 (9.2) used NUMBER arithmetic (approximately 38 significant digits).

Therefore, if you are dealing with results of greater than 9 significant digits, then one of the literals should be in decimal format to prevent numeric overflow errors. For example, in release 10g the computation of v1 in the following example causes a numeric overflow error:

DECLARE
  v1 NUMBER(38);
BEGIN
  v1 := 256*256*256*256;
  DBMS_OUTPUT.PUT_LINE(v1);
END;
/

The solution to the error is to specify one of the numeric literals as a decimal (256.0), as follows:

DECLARE
  v1 NUMBER(38);
BEGIN
  v1 := 256*256*256*256.0;
  DBMS_OUTPUT.PUT_LINE(v1);
END;
/

SHARED_SERVERS Parameter

When the initialization parameter SHARED_SERVERS is dynamically changed to 0, no new clients can connect in shared mode, but existing shared server connections can continue to operate. Prior to Oracle Database 10g Release 1 (10.1), existing shared server connections would hang in this situation.