Download Overview of Oracle 10g

Overview of Oracle 10g
These notes give an overview of the new features of oracle database introduced in
10g.
Grid Computing
Let’s get started with a brief overview of Oracle Grid Computing. Oracle
describes grid computing as “separate groups of users dynamically sharing computer
resources across high-speed networks to meet changing computational needs.” Grid
environments utilize farms of low-cost computer servers in a shared environment. Oracle
uses its Real Application Cluster technology (discussed below) along with the 10G
Database and 10G Application Server to create the shared computing infrastructure
required to implement grid computing.
The optimal grid environment uses an interconnected server farm with each server
containing one to four CPUs. The servers are connected to a shared disk system using
network-attached storage (NAS) or a storage area network (SAN) technologies as the
connectivity mechanism. High-speed network connections between the hardware servers
themselves and from the hardware servers to the shared disk system allow end-users and
administrators to view the environment as a single application architecture (refer to
Figure below).
Real Application Cluster enhancements in Oracle10G allow hardware servers to
be seamlessly added to an application requiring more resources for a particular time
period. Conversely, when hardware resource requirements are low, the extra computing
horsepower can be easily freed and used by other applications in the grid.
Oracle10G enhances Oracle Enterprise Manager functionality to manage the grid
with a single interface. Oracle’s Grid Control is a web-enabled toolset that allows
administrators to group hardware platforms, databases, and application server
installations and manage them as a single entity. Administrators are able to call other
utilities (Data Pump, Transportable Tablespace, Oracle’s new job scheduler) from within
Grid Control to modify, monitor and tune databases throughout the grid.
Grid Control also simplifies grid administration by automating the installation,
configuration and cloning of Application Server 10G and Database 10G implementations
across multiple nodes. Grid Control monitoring views the entire grid as a single unit and
provides drill down capabilities to identify problems with individual components.
Automatic Storage Management (ASM)
Oracle10G provides its own disk storage management system. Database
administrators are no longer required to use hardware vendor or third-party disk volume
managers to provide striping and mirroring functionality. ASM manages the raw disks
within the Oracle database architecture. Administrators are able to assign disks to disk
groups, which can then be striped and/or mirrored to provide high performance and high
availability. During tablespace creation, the administrator assigns the tablespace datafile
to a disk group. This differs from previous Oracle releases which required that datafiles
be assigned to the individual disks themselves.
Interestingly enough, Oracle’s default stripe size is one megabyte. This differs
from most disk storage management systems, which often utilize 32K or 64K stripe sizes.
Oracle found that one-megabyte stripes on disks provided a very high level of data
transfer and best met the needs of disk intensive applications. One can only assume that
advancements in disk storage technology have allowed Oracle to access the data in onemegabyte chunks and not drive disk utilization to unacceptable levels.
Administrators provide disk mirroring by creating failure groups. The DBA
creates the appropriate number of failure groups to accommodate the data requiring disk
fault tolerance. ASM’s mirroring capability ranges from the mirroring of individual
datafiles to entire disk arrays, providing administrators with a high level of flexibility
when creating fault-tolerant disk subsystems. The data is duplicated on separate disks in
one-megabyte mirror “chunks.”
Administrators can choose from the following mirroring options in ASM:

External – no mirroring

Normal – data is mirrored on two separate disks. This is the default
setting.

High Redundancy – data is mirrored on there separate disks providing
three-way mirroring capabilities.
ASM requires its own instance, which identifies the various disk groups and files
during instance startup. The ASM instance then mounts the disks under its control and
creates an extent map, which is passed to the database instances. ASM does not perform
the I/O for the database instances; it is only used to manage the various disk groups under
its control. ASM is only activated when individual datafiles are created or dropped or
disks are added and removed from the disk groups. When new disks are added or
removed from the disk group, ASM automatically rebalances the files contained in the
disk group while the database is open and functioning.
ASM is able to balance the I/O for multiple databases across all managed devices
providing load balancing for multiple applications. In Oracle10G Grid implementations,
ASM is able to reassign disks from one node to another providing additional load
balancing capabilities.
Oracle Enterprise Manager (OEM) for Oracle10G and the Database Configuration
Assisstant (DBCA) have been updated to allow administrators to configure and manage
databases using ASM.
Real Application Clusters (RAC)
One of RAC’s requirements is that clustering software (sometimes called
clusterware) be used to connect the hardware platforms together. This underlying
clustering software was purchased either from the hardware vendor or a third-party
clustering software provider. RAC is installed on top of the cluster environment and
works in conjunction with the underlying clustering software to allow the application
programs to view the multiple instances as a single entity.
One of the problems using previous release of RAC was identifying exactly
whose software it was causing the problem in the first place. Was it the RAC software or
was it the clustering software provided by the hardware or third party vendor? Oracle10G
solves this problem by providing its own clustering software called Portable Clusterware.
Portable Clusterware can now be used in place of the hardware or third-party vendor’s
clustering software.
Flashback Database
How many times have database recoveries been performed because of incorrect
changes made to database data? A user deletes or updates “one too many rows” by
mistake and the result is a time-consuming and error prone process to restore and recover
the database to a point-in-time before the error occurred. Oracle Education states that
point-in-time recoveries are responsible for the majority of DBA errors and the resulting
unrecoverable databases.
A common question in the Oracle DBA2 backup and recovery class is “why can’t
I just roll the database back to remove unwanted changes instead of restoring the database
from a backup and applying the redo logs to roll forward to a point-in-time before the
error occurred?” The question was invariably followed by “don’t you think that would be
easier?” The answer was always the same “yes, it would be easier, but the Oracle
database doesn’t have that capability.”
Until Oracle10G that is… Oracle10G’s Flashback Database feature provides a
new tool in the DBA’s recovery toolbox. Flashback Database allows the DBA to “roll
back” a table, set of tables or the entire database to a previous point-in-time.
A flashback log is used to capture old versions of changed data blocks. During
Flashback execution, the Oracle database restores the old versions of the data blocks to
their original locations which allows the database to be rolled back to a previous point-intime. Oracle provides the following example in its sales collateral to highlight how
simple this new Flashback Database Feature is:
SQL> flashback database to ‘2:05 PM’;
Compare that to previous point-in-time recovery procedures, which required the
entire database to be restored to a previous backup and then rolled forward using archived
and online redo log files to replay the changes to a point-in-time before the error
occurred.
Flashback Backup
Oracle10G also uses the flashback logs to provide the mechanism for its
Flashback Backup feature. Flashback Backup allows administrators to take a base level
backup and then perform nightly incremental backups to roll the backup database forward
to the current point-in-time. Since the changed blocks are recorded by the database, a full
scan of all of the database blocks is no longer required to keep the backup database
synchronized with its production counterpart.
Automatic SGA Management
Oracle has simplified the management of the Oracle SGA. In previous releases,
database administrators allocated chunks of memory to the different caches (data buffer,
shared pool, large pool, java pool etc.) by setting their associated parameters in the
database’s parameter file.
Oracle10G has reduced the number of memory allocation parameters to two, one
for the SGA and one for the PGA. Oracle10G will divide the memory resources among
the different SGA memory areas and modify these allocations dynamically based on
application workload changes.
Automatic Workload Repository (AWR)
The Automatic Workload Repository collects performance statistics (and the SQL
text itself) for all SQL statements executed in the database. It is a historical performance
datawarehouse that stores SQL statement CPU, memory and I/O resource consumption.
AWR runs by default and Oracle states that it does not add a noticeable level of
overhead. The information in this repository is used as input for the toolsets discussed
later in this article. This historical information will help administrators finally answer
questions like “my program ran long two days ago, can you fix it?”
A new background server process (MMON) takes snapshots of the in-memory
database statistics (much like STATSPACK) and stores this information in the repository.
MMON also provides Oracle10G with a server initiated alert feature, which notifies
database administrators of potential problems (out of space, max extents reached,
performance thresholds, etc.).
Automatic Database Diagnostic Monitor (ADDM)
The Automatic Database Diagnostic Monitor analyzes the information contained
in the Automatic Workload Repository every 30 minutes to pinpoint problems and
provide automated recommendations to DBAs. If ADDM requires additional information
to make a decision, it will activate other advisories to gather more information. ADDM’s
output includes a plethora of reports, charts, graphs, heartbeats and related visual aids.
ADDM can also be manually activated from OEM or the command line to
provide users with a top-down analysis of performance bottlenecks and their associated
resolutions.
SQL Tuning Advisor
Oracle’s latest advisor will help Oracle DBAs with the “fine art” of SQL tuning.
In the past SQL tuning could be defined as more of an art than as a science.
Administrators required extensive tuning experience before they could be described as
“expert SQL tuners.” Oracle claims to have embedded hundreds of year’s worth of tuning
experience into the SQL Tuning Advisor. Hopefully, this new advisor will help put the
science back into the SQL tuning process.
The SQL Tuning Advisor uses the Automated Workload Repository to capture
and identify high resource consuming SQL statements. An intelligent analyzer is then
used to assist administrators in tuning the offending SQL statements.
The tuning advisor sends the SQL statement being analyzed to the Automatic
Tuning Optimizer to perform the following in-depth analyses:

Statistics Analysis – the utility checks for stale or missing statistics, which
may have a detrimental effect on the query’s optimization.

SQL Profiling – reviews past executions of the SQL statement to provide
further information for recommendations.

Access Path Analysis – determines if additional objects (indexes,
materialized views) can be created to improve the statement’s
performance.

SQL Structure Analysis – reviews the SQL statement’s coding structure to
determine if it can be altered to increase performance.
The Automatic Tuning Advisor uses the Oracle optimizer to make its
recommendations. Unlike run-time optimization, which focuses on quick optimization,
Automatic Tuning Advisor calls to the optimizer are not limited by time constraints. As a
result, queries tuned by the advisor have a much better chance of having a finely tuned
optimization plan created.
The SQL Tuning Advisor will be very beneficial to administrators who support
third-party applications. In previous releases, once the administrator identified the canned
application’s poorly performing SQL, the third-party vendor was contacted to change the
SQL code and the changed code implemented in test and finally in production to
implement the tuning change. Anyone who has experience with third-party application
vendors knows that this is often a time consuming (if not impossible) process.
The SQL Tuning Advisor uses the Oracle10G cost based optimizer to rewrite the
poorly performing SQL and create a SQL profile, which is stored in the data dictionary.
Each time the poorly performing SQL statement executes, the rewritten statement stored
in the data dictionary is used in its place. No vendor assistance required!
Transportable Tablespace
In previous releases, the transportable tablespace feature could only be used to
transfer data to databases running on the same operating system. In Oracle10G, Oracle
has enhanced the transportable tablespace feature to allow the tablespace to be transferred
to databases running on different operating systems.
Data Pump
Describing the Oracle Export and Import utilities as slow is like saying the Titanic
sprung a small leak. Stories of Export and Import executions running for hours (and
sometime days) are commonplace. Oracle has finally created a new data movement
utility, called Data Pump, to increase the performance of data transfers. Oracle states that
Data Pump’s performance on data retrieval is 60% faster than Export and 15 to 20 times
faster on data input than Import. In addition, Oracle states that Data Pump is able to take
advantage of parallel processing to increase performance. Hopefully, this will alleviate
the performance issues related to transferring data between Oracle databases.
Oracle Streams Database Transfer
Oracle10G also utilizes the cross-platform feature of transportable tablespaces to
allow administrators to move or copy entire databases from one platform to another. The
database can be detached, moved to another server, attached and the workload moved
with one command. The primary use of this feature will be to load balance the different
servers in a grid environment.
Oracle Scheduler
Oracle10G introduces a robust job scheduler to facilitate job execution in grid
computing. But, you don’t have to run a grid to take advantage of the benefits the Oracle
Scheduler offers. Users are able to create complex job streams that execute PL/SQL, Java
and C programs. Conditional logic can be used to interrogate job return codes and
provide job stream branching capabilities. Jobs can also be grouped into job classes,
which can then be given a predefined set of computing resources by Oracle’s Database
Resource Manager to provide job prioritization.