Monday, October 25, 2010

Oracle 11g crucial new features for DBA

Hi ,
Below are some of the crucial new features that should be known by DBA working on oracle 11g Databases:


Oracle Database 11.1 Top New Feature for DBAs : SUMMARY
=====================================

1) Automatic Diagnostic Repository [ADR]

2) Database Replay

3) Automatic Memory Tuning

4) Case sensitive password

5) Virtual columns and indexes

6) Interval Partition and System Partition

7) The Result Cache

8) ADDM RAC Enhancements

9) SQL Plan Management and SQL Plan Baselines

10) SQL Access Advisor & Partition Advisor

11) SQL Query Repair Advisor

12) SQL Performance Analyzer (SPA) New

13) DBMS_STATS Enhancements

14) The Result Cache

15) Total Recall (Flashback Data Archive)

Note: The above are only top new features, there are other features as well introduced in 11g which will be included subsequently

Oracle 11.1 Database DBA New Features with brief explanation
==========================================

# Database Capture/replay database workloads :
This allows the total database workload to be captured, transferred to a test database create from a backup or standby database, then replayed to test the affects of an upgrade or system change. Currently, these are working to a capture performance overhead of 5%, so this will capture real production workloads


# Automatic Memory Tuning:

Automatic PGA tuning was introduced in Oracle 9i. Automatic SGA tuning was already
introduced in Oracle 10g. But In 11g, all memory can be tuned automatically by setting one parameter. We can literally tell Oracle how much memory it has and it determines how much to use for PGA, SGA and OS Processes. Maximum and minimum thresholds can be set.

# Interval partitioning for tables :

Interval partitions are extensions to range partitioning. These provide automation for equi-sized range partitions. Partitions are created as metadata and only the start partition is made persistent. The additional segments are allocated as the data arrives. The additional partitions and local indexes are automatically created.

# Feature Based Patching:

All one-off patches will be classified as to which feature they affect. This allows you to easily identify which patches are necessary for the features you are using. EM will allow you to subscribe to a feature based patching service, so EM automatically scans for available patches for the features you are using

# RMAN UNDO bypass :

Rman backup can bypass undo. Undo tablespaces are getting huge, but contain lots of useless information. Now rman can bypass those types of tablespace. Great for exporting a tablespace from backup.

# Virtual columns/indexes :

User can create Virtual index on table. This Virtual index is not visible to optimizer, so it will
not affect performance, Developer can user HINT and see is Index is useful or not.Invisible
Indexesprevent premature use of newly created indexes

# New default audit settings :

Oracle database where general database auditing was "off" by default, logging is intended to be enabled by default with the Oracle Database 11g beta secure configuration. Notable performance improvements are planned to be introduced to reduce the performance degradation typically associated with auditing.

# Case sensitive password :

Passwords are expected to also become case sensitive This and other changes should result in better protection against password guessing scenarios. For
example, in addition to limiting the number of failed login attempts to 10 (default configuration in 10gR2), Oracle 11g beta’s planned default settings should expire passwords every 180 days, and limit to seven the number of times a user can login with an expired password before disabling access.

# Faster DML triggers : Create a disabled trigger; specify trigger firing order

# Fine grained access control for Utl_TCP:

in 10g all port are available, now it is controlled.

# Data Guard supports "Flashback Standby"

# New Trigger features

# Partitioning by logical object and automated partition creation.

# LOB's - New high-performance LOB features.

# New Oracle11g Advisors

# Enhanced Read only tables

# Table trigger firing order

# Enhanced Index rebuild online : - Online index build with NO pause to DML.

# No recompilation of dependent objects:- When

A) Columns added to tables
B) Procedures added to packages

# Improved optimizer statistics collection speed

# Online index build with NO pause to DML

# Read only table :-

alter table t read only

alter table t read write

Oracle 11g Database SQL/PL-SQL New Features
----------------------------------------------

> Fine Grained Dependency Tracking:

In 11g we track dependencies at the level of element within unit. so that these changes have no consequence

• Transparent performance improvement
•Unnecessary recompilation certainly consumes CPU

create table t(a number)

create view v as select a from t

alter table t add(Unheard_Of number)

select status from User_Objects where Object_Name = 'V'
- -----
VALID

No recompilation of dependent objects when Columns added to tables OR Procedures
added to packages

> Named and Mixed Notation from SQL:

select fun(P4=>10) from DUAL

In 10g not possible to call function in select statment by passing 4th parameter,
but in 11g it is possible

> PL/SQL "continue" keyword - It is same as we read in c/c++ loop

> Support for “super”: It is same "super" in Java.

> Powerfull Regular Expression:

Now we can access data between TAGS like data between tags .........

The new built-in REGEXP_COUNT returns the number of times the pattern is matched in the
input string.

> New table Data Type "simple_integer"

> SQL Performance Analyzer(SPA) :

It is same as Database replay except it not capture all transaction.The SQL Performance Analyzer (SPA) leverages existing Oracle Database 10g SQL tuning components. The SPA provides the ability to capture a specific SQL workload in a SQL Tuning Set, take a performance baseline before a major database or system change, make the desired change to the system, and then replay the SQL workload against the modified database or configuration. The before and after performance of the SQL workload can then be compared with just a few clicks of the mouse. The DBA only needs to isolate any SQL statements that are now performing poorly and tune them via the SQL Tuning Advisor

> Caching The Results with /*+ result_cache */ :

select /*+ result_cache */ * from my_table, New for Oracle 11g, the result_cache hint caches the result set of a select statement. This is similar to alter table table_name cache,but as you can adding predicates makes /*+ result_cache */ considerably more powerful by caching a subset of larger tables and common queries.

select /*+ result_cache */ col1, col2, col3 from my_table where colA = :B1

> The compound trigger :

A compound trigger lets you implement actions for each of the table DML timing points in a single trigger

> PL/SQL unit source can exceeds 32k characters

> Easier to execute table DDL operations online:

Option to wait for active DML operations instead of aborting

> Fast add column with default value:

Does not need to update all rows to default value.

Oracle 11g Database Backup & Recovery New Features
------------------------------------------------

* Enhanced configuration of archive deletion policies Archive can be deleted , if it is not need DG , Streams Flashback etc When you CONFIGURE an archived log deletion policy applies to all archiving destinations, including the flash recovery area. BACKUP ... DELETE
INPUT and DELETE... ARCHIVELOG use this configuration, as does the flash recovery area.
When we back up the recovery area, RMAN can fail over to other archived redo log
destinations if the flash recovery area is inaccessible.

* Configuring backup compression:

In 11g can use CONFIGURE command to choose between the BZIP2 and ZLIB compression
algorithms for RMAN backups.

* Active Database Duplication:

Now DUPLICATE command is network aware i.e.we can create a duplicate or standby
database over the network without taking backup or using old backup.

* Parallel backup and restore for very large files:

RMAN Backups of large data files now use multiple parallel server processes to efficiently
distribute theworkload for each file. This features improves the performance of backups.

* Improved block media recovery performance:

RECOVER command can recover individual data blocks.
RMAN take older, uncorrupted blocks from flashback and the RMAN can use these blocks,
thereby speeding up block media recovery.

* Fast incremental backups on physical standby database:

11g has included new feature of enable block change tracking on a physical standby
database (ALTER DATABASE ENABLE/DISABLE BLOCK CHANGE TRACKING SQL statement).
This new 11g feature enables faster incremental backups on a physical standby database
than in previous releases.because RMAN identifywe the changed blocks sincethe last
incremental backup.

11g ASM New Features
-----------------------

The new features in Automatic Storage Management (ASM) extend the storage
management automation, improve scalability, and further simplify management for
Oracle Database files.

■ ASM Fast Mirror Resync

A new SQL statement, ALTER DISKGROUP ... DISK ONLINE, can be executed
after a failed disk has been repaired. The command first brings the disk online for writes so that no new writes are missed. Subsequently, it initiates a copy of all extents marked as stale on a disk from their redundant copies.
This feature significantly reduces the time it takes to repair a failed diskgroup,potentially from hours to minutes. The repair time is proportional to the number of extents that have been written to or modified since the failure.

■ ASM Manageability Enhancements

The new storage administration features for ASM manageability include the following:

■ New attributes for disk group compatibility
To enable some of the new ASM features, you can use two new disk group
compatibility attributes, compatible.rdbms and compatible.asm. These
attributes specify the minimum software version that is required to use disk
groups for the database and for ASM, respectively. This feature enables
heterogeneous environments with disk groups from both Oracle Database 10g and
Oracle Database 11g. By default, both attributes are set to 10.1. You must advance
these attributes to take advantage of the new features.

■ New ASM command-line utility (ASMCMD) commands and options

ASMCMD allows ASM disk identification, disk bad block repair, and backup and
restore operations in your ASM environment for faster recovery.

■ ASM fast rebalance

Rebalance operations that occur while a disk group is in RESTRICTED mode
eliminate the lock and unlock extent map messaging between ASM instances in
Oracle RAC environments, thus improving overall rebalance throughput.
This collection of ASM management features simplifies and automates storage
management for Oracle databases.

■ ASM Preferred Mirror Read

When ASM failure groups are defined, ASM can now read from the extent that is
closest to it, rather than always reading the primary copy. A new initialization parameter, ASM_PREFERRED_READ_FAILURE_GROUPS, lets the ASM administrator specify a list of failure group names that contain the preferred read disks for each node in a cluster.

In an extended cluster configuration, reading from a local copy provides a great
performance advantage. Every node can read from its local diskgroup (failure group),
resulting in higher efficiency and performance and reduced network traffic.

■ ASM Rolling Upgrade

Rolling upgrade is the ability of clustered software to function when one or more of the nodes in the cluster are at different software versions. The various versions of the software can still communicate with each other and provide a single system image.
The rolling upgrade capability will be available when upgrading from Oracle
Database 11g Release 1 (11.1).

This feature allows independent nodes of an ASM cluster to be migrated or patched without affecting the availability of the database. Rolling upgrade provides higher uptime and graceful migration to new releases.

■ ASM Scalability and Performance Enhancements

This feature increases the maximum data file size that Oracle can support to 128 TB.
ASM supports file sizes greater than 128 TB in any redundancy mode. This provides
near unlimited capacity for future growth. The ASM file size limits are:

■ External redundancy - 140 PB
■ Normal redundancy - 42 PB
■ High redundancy - 15 PB

Customers can also increase the allocation unit size for a disk group in powers of 2 up to 64 MB.

■ Convert Single-Instance ASM to Clustered ASM

This feature provides support within Enterprise Manager to convert a non-clustered
ASM database to a clustered ASM database by implicitly configuring ASM on all
nodes. It also extends the single-instance to Oracle RAC conversion utility to support standby databases.

Simplifying the conversion makes it easier for customers to migrate their databases and achieve the benefits of scalability and high availability provided by Oracle RAC.

■ New SYSASM Privilege for ASM Administration

This feature introduces the new SYSASM privilege to allow for separation of database management and storage management responsibilities.
The SYSASM privilege allows an administrator to manage the disk groups that can be shared by multiple databases. The SYSASM privilege provides a clear separation of
duties from the SYSDBA privilege.





Best regards,

Rafi.

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