There are many features in the Oracle 10g which got introduced for the
first time in the RDBMS. These features not only made the DBA's life
easy but also gave the DBAs time to work on the important tasks instead
of spending time in analysing the database memory, storage, file system,
etc. I will go through every new feature in details in coming few days,
but to begin with I will list here a brief description of all the
latest features.
Oracle Database 10g has a long list of impressive architecture enhancements over its previous versions. Oracle has made this database very sophisticated and powerful, and has automated many of the traditional and mundane administrative functions. Oracle has tried to automate as much database functionality as possible and made it more scalable. Several changes have been made to improve memory structures, resource management, storage handling, SQL tuning, data movement, recovery speed, and globalization. This chapter will go over the most notable revisions to the database architecture for releases 1 and 2 of the Oracle Database 10g and any significant improvements for Release 2 is specifically mentioned in this and all chapters.
SYSAUX Tablespace
The SYSAUX tablespace is an auxiliary tablespace that provides storage for all non sys-related tables and indexes that would have been placed in the SYSTEM tablespace. SYSAUX is required for all Oracle Database 10g installations and should be created along with new installs or upgrades. Many database components use SYSAUX as their default tablespace to store data. The SYSAUX tablespace also reduces the number of tablespaces created by default in the seed database and user-defined database.
Rename Tablespace Option
Oracle Database 10g has implemented the provision to rename tablespaces. To accomplish this in older versions, you had to create a new tablespace, copy the contents from the old tablespace to the new tablespace, and drop the old tablespace. The Rename Tablespace feature enables simplified processing of tablespace migrations within a database and ease of transporting a tablespace between two databases.
Automatic Storage Management
Automatic Storage Management (ASM) is a new database feature for efficient management of storage with round-the-clock availability. It helps prevent the DBA from managing thousands of database files across multiple database instances by using disk groups. These disk groups are comprised of disks and resident files on the disks. ASM does not eliminate any existing database functionalities with file systems or raw devices, or Oracle Managed Files (OMFs). ASM also supports RAC configurations.
Temporary Tablespace Group
A temporary tablespace is used by the database for storing temporary data, which is not accounted for in recovery operations. A temporary tablespace group (TTG) is a group of temporary tablespaces. A TTG contains at least one temporary tablespace, with a different name from the tablespace. Multiple temporary tablespaces can be specified at the database level and used in different sessions at the same time.
In Oracle Database 10g, each database user will have a permanent tablespace for storing permanent data and a temporary tablespace for storing temporary data. In previous versions of Oracle, if a user was created without specifying a default tablespace, SYSTEM tablespace would have become the default tablespace. For Oracle Database 10g, a default permanent tablespace can be defined to be used for all new users without a specific permanent tablespace.
BigFile Tablespace
Gone are those days of tablespaces in the range of a few megabytes. These days, database tables hold a lot of data and are always hungry for storage. To address this craving, Oracle has come up with the Bigfile tablespace concept. A BigFile tablespace (BFT) is a tablespace containing a single, very large data file. With the new addressing scheme in 10g, four billion blocks are permitted in a single data file and file sizes can be from 8TB to 128TB, depending on the block size. To differentiate a regular tablespace from a BFT, a regular tablespace is called a small file tablespace. Oracle Database 10g can be a mixture of small file and BigFile tablespaces.
BFTs are supported only for locally managed tablespaces with ASM segments and locally managed undo and temporary tablespaces. When BFTs are used with Oracle Managed Files, data files become completely transparent to the DBA and no reference is needed for them. BFT makes a tablespace logically equivalent to data files (allowing tablespace operations) of earlier releases.
Prior to Oracle Database 10g, K and M were used to specify data file sizes. Because the newer version introduces larger file sizes up to 128TB using BFTs, the sizes can be specified using G and T for gigabytes and terabytes, respectively. For using BFT, the underlying operating system should support Large Files. In other words the file system should have Large File Support (LFS).
Cross-Platform Transportable Tablespaces
In Oracle 8i database, the transportable tablespace feature enabled a tablespace to be moved across different Oracle databases using the same operating system. Oracle Database 10g has significantly improved this functionality to permit the movement of data across different platforms. This will help transportable tablespaces to move data from one environment to another on selected heterogeneous platforms (operating systems). Using cross-platform transportable tablespaces, a database can be migrated from one platform to another by rebuilding the database catalog and transporting the user tablespaces. By default, the converted files are placed in the flash recovery area (also new to Oracle Database 10g), which is discussed later in this chapter. A list of fully supported platforms can be found in v$transportable_platform.
Performance Management Using AWR
Automatic Workload Repository (AWR) is the most important feature among the new Oracle Database 10g manageability infrastructure components. AWR provides the background services to collect, maintain, and utilize the statistics for problem detection and self-tuning. The AWR collects system-performance data at frequent intervals (generally 60 minutes) and stores them as historical system workload information for analysis. These metrics are stored in the memory for performance reasons. These statistics are regularly written from memory to disk by a new background process called Memory Monitor (MMON). This data will later be used for analysis of performance problems that occurred in a certain time period and to do trend analysis. Oracle does all this without any DBA intervention. Automatic Database Diagnostic Monitor (ADDM), which is discussed in the next section, analyzes the information collected by the AWR for database-performance problems.
Automatic Database Diagnostic Monitor (ADDM)
Automatic Database Diagnostic Monitor (ADDM) is the best resource for database tuning. Introduced in 10g, ADDM provides proactive and reactive monitoring instead of the tedious tuning process found in earlier Oracle versions. Proactive monitoring is done by ADDM and Server Generated Alerts (SGAs). Reactive monitoring is done by the DBA, who does manual tuning through Oracle Enterprise Manager or SQL scripts.
Statistical information captured from SGAs is stored inside the workload repository in the form of snapshots every 60 minutes. These detailed snapshots (similar to STATSPACK snapshots) are then written to disk. The ADDM initiates the MMON process to automatically run on every database instance and proactively find problems.
DROP DATABASE Command
Oracle Database 10g has introduced a means to drop the entire database with a single command: DROP DATABASE. The DROP DATABASE command deletes all database files, online log files, control files, and the server parameter (spfile) file. The archive logs and backups, however, have to be deleted manually.
Data Pump Utilities
Data Pump is the new high-speed infrastructure for data and metadata movement in Oracle Database 10g. The Data Pump commands are similar to the traditional export and import commands, but they are different products. Data Pump provides a substantiale performance improvement over the original export and import utilities. It also provides faster data load and unload capability to existing tables. Using Data Pump, platform-independent flat files can be moved between multiple servers. You can use the new network mode to transfer data using database links.
Export and import operations in Data Pump can detach from a long-running job and reattach to it later with out affecting the job. You can also remap data during export and import processes. The names of data files, schema names, and tablespaces from the source can be altered to different names on the target system. It also supports fine-grained object selection using the EXCLUDE, INCLUDE, and CONTENT parameters.
Data Pump Export (dpexp) is the utility for unloading data and metadata from the source database to a set of operating system files (dump file sets). Data Pump Import (dpimp) is used to load data and metadata stored in these export dump file sets to a target database.
In Oracle Database 10g Release 2, a default DATA_PUMP_DIR directory object and additional DBMS_DATAPUMP API calls have been added, along with provisions for compression of metadata in dump files, and the capability to control the dump file size with the FILESIZE parameter.
This section has reviewed the significant new features introduced in Oracle Database 10g. I will touch over the new processes introduced in Oracle Database 10g to support these features.
Oracle Database 10g has a long list of impressive architecture enhancements over its previous versions. Oracle has made this database very sophisticated and powerful, and has automated many of the traditional and mundane administrative functions. Oracle has tried to automate as much database functionality as possible and made it more scalable. Several changes have been made to improve memory structures, resource management, storage handling, SQL tuning, data movement, recovery speed, and globalization. This chapter will go over the most notable revisions to the database architecture for releases 1 and 2 of the Oracle Database 10g and any significant improvements for Release 2 is specifically mentioned in this and all chapters.
SYSAUX Tablespace
The SYSAUX tablespace is an auxiliary tablespace that provides storage for all non sys-related tables and indexes that would have been placed in the SYSTEM tablespace. SYSAUX is required for all Oracle Database 10g installations and should be created along with new installs or upgrades. Many database components use SYSAUX as their default tablespace to store data. The SYSAUX tablespace also reduces the number of tablespaces created by default in the seed database and user-defined database.
Rename Tablespace Option
Oracle Database 10g has implemented the provision to rename tablespaces. To accomplish this in older versions, you had to create a new tablespace, copy the contents from the old tablespace to the new tablespace, and drop the old tablespace. The Rename Tablespace feature enables simplified processing of tablespace migrations within a database and ease of transporting a tablespace between two databases.
Automatic Storage Management
Automatic Storage Management (ASM) is a new database feature for efficient management of storage with round-the-clock availability. It helps prevent the DBA from managing thousands of database files across multiple database instances by using disk groups. These disk groups are comprised of disks and resident files on the disks. ASM does not eliminate any existing database functionalities with file systems or raw devices, or Oracle Managed Files (OMFs). ASM also supports RAC configurations.
Temporary Tablespace Group
A temporary tablespace is used by the database for storing temporary data, which is not accounted for in recovery operations. A temporary tablespace group (TTG) is a group of temporary tablespaces. A TTG contains at least one temporary tablespace, with a different name from the tablespace. Multiple temporary tablespaces can be specified at the database level and used in different sessions at the same time.
In Oracle Database 10g, each database user will have a permanent tablespace for storing permanent data and a temporary tablespace for storing temporary data. In previous versions of Oracle, if a user was created without specifying a default tablespace, SYSTEM tablespace would have become the default tablespace. For Oracle Database 10g, a default permanent tablespace can be defined to be used for all new users without a specific permanent tablespace.
BigFile Tablespace
Gone are those days of tablespaces in the range of a few megabytes. These days, database tables hold a lot of data and are always hungry for storage. To address this craving, Oracle has come up with the Bigfile tablespace concept. A BigFile tablespace (BFT) is a tablespace containing a single, very large data file. With the new addressing scheme in 10g, four billion blocks are permitted in a single data file and file sizes can be from 8TB to 128TB, depending on the block size. To differentiate a regular tablespace from a BFT, a regular tablespace is called a small file tablespace. Oracle Database 10g can be a mixture of small file and BigFile tablespaces.
BFTs are supported only for locally managed tablespaces with ASM segments and locally managed undo and temporary tablespaces. When BFTs are used with Oracle Managed Files, data files become completely transparent to the DBA and no reference is needed for them. BFT makes a tablespace logically equivalent to data files (allowing tablespace operations) of earlier releases.
Prior to Oracle Database 10g, K and M were used to specify data file sizes. Because the newer version introduces larger file sizes up to 128TB using BFTs, the sizes can be specified using G and T for gigabytes and terabytes, respectively. For using BFT, the underlying operating system should support Large Files. In other words the file system should have Large File Support (LFS).
Cross-Platform Transportable Tablespaces
In Oracle 8i database, the transportable tablespace feature enabled a tablespace to be moved across different Oracle databases using the same operating system. Oracle Database 10g has significantly improved this functionality to permit the movement of data across different platforms. This will help transportable tablespaces to move data from one environment to another on selected heterogeneous platforms (operating systems). Using cross-platform transportable tablespaces, a database can be migrated from one platform to another by rebuilding the database catalog and transporting the user tablespaces. By default, the converted files are placed in the flash recovery area (also new to Oracle Database 10g), which is discussed later in this chapter. A list of fully supported platforms can be found in v$transportable_platform.
Performance Management Using AWR
Automatic Workload Repository (AWR) is the most important feature among the new Oracle Database 10g manageability infrastructure components. AWR provides the background services to collect, maintain, and utilize the statistics for problem detection and self-tuning. The AWR collects system-performance data at frequent intervals (generally 60 minutes) and stores them as historical system workload information for analysis. These metrics are stored in the memory for performance reasons. These statistics are regularly written from memory to disk by a new background process called Memory Monitor (MMON). This data will later be used for analysis of performance problems that occurred in a certain time period and to do trend analysis. Oracle does all this without any DBA intervention. Automatic Database Diagnostic Monitor (ADDM), which is discussed in the next section, analyzes the information collected by the AWR for database-performance problems.
Automatic Database Diagnostic Monitor (ADDM)
Automatic Database Diagnostic Monitor (ADDM) is the best resource for database tuning. Introduced in 10g, ADDM provides proactive and reactive monitoring instead of the tedious tuning process found in earlier Oracle versions. Proactive monitoring is done by ADDM and Server Generated Alerts (SGAs). Reactive monitoring is done by the DBA, who does manual tuning through Oracle Enterprise Manager or SQL scripts.
Statistical information captured from SGAs is stored inside the workload repository in the form of snapshots every 60 minutes. These detailed snapshots (similar to STATSPACK snapshots) are then written to disk. The ADDM initiates the MMON process to automatically run on every database instance and proactively find problems.
DROP DATABASE Command
Oracle Database 10g has introduced a means to drop the entire database with a single command: DROP DATABASE. The DROP DATABASE command deletes all database files, online log files, control files, and the server parameter (spfile) file. The archive logs and backups, however, have to be deleted manually.
Data Pump Utilities
Data Pump is the new high-speed infrastructure for data and metadata movement in Oracle Database 10g. The Data Pump commands are similar to the traditional export and import commands, but they are different products. Data Pump provides a substantiale performance improvement over the original export and import utilities. It also provides faster data load and unload capability to existing tables. Using Data Pump, platform-independent flat files can be moved between multiple servers. You can use the new network mode to transfer data using database links.
Export and import operations in Data Pump can detach from a long-running job and reattach to it later with out affecting the job. You can also remap data during export and import processes. The names of data files, schema names, and tablespaces from the source can be altered to different names on the target system. It also supports fine-grained object selection using the EXCLUDE, INCLUDE, and CONTENT parameters.
Data Pump Export (dpexp) is the utility for unloading data and metadata from the source database to a set of operating system files (dump file sets). Data Pump Import (dpimp) is used to load data and metadata stored in these export dump file sets to a target database.
In Oracle Database 10g Release 2, a default DATA_PUMP_DIR directory object and additional DBMS_DATAPUMP API calls have been added, along with provisions for compression of metadata in dump files, and the capability to control the dump file size with the FILESIZE parameter.
This section has reviewed the significant new features introduced in Oracle Database 10g. I will touch over the new processes introduced in Oracle Database 10g to support these features.
No comments:
Post a Comment