Shulou(Shulou.com)06/01 Report--

I. Oracle architecture

The architecture of the database refers to the composition and working process of the database, as well as the organization and management mechanism of the data in the database. To understand the architecture of the Oracle database, we must understand the main components and important concepts of the Oracle system.

1. Overview of Oracle architecture

The Oracle architecture consists of a series of components, as shown in the following figure, which shows the main components of the Oracle architecture, including instances, user processes, server processes, data files, and other files, such as parameter files, password files, and archive log files. As can be seen from the figure, instances and databases are the core components of the Oracle database architecture and the two most important concepts; one of the most important tasks of DBA is to maintain the normal operation of the instances and the database itself.

1) instance

An Oracle instance is a collection of background processes and memory structures, and you must start the instance to access the data in the database. When the Oracle instance starts, a system global area (SGA) is assigned and a series of Oracle background processes are started. There are two types of Oracle instances: single-process instances and multi-process instances. Single-process Oracle instances use one process to perform all the operations of Oracle, and only one user is allowed to access Oracle instances in a single-process environment; multi-process Oracle instances (also known as multi-user Oracle) use multiple processes to execute different parts of Oracle, and there is a process for each connected user.

2) Database

A database is a collection of data, which physically refers to a set of operating system files that store database information. Each database has a logical structure and a physical structure. Physical structure refers to a set of operating system files that make up a database, which is mainly composed of three types of files: data files, control files, and redo log files. The logical structure of database refers to the logical storage structure of database data (such as table space, segment) and schema objects (such as table, view, etc.).

3) pluggable database

Starting with the Oracle 12c release, Oracle introduced the concept of pluggable databases, which were created for cloud computing. The pluggable structure consists of a container database (CDB) and several assemblable databases (PDB). Each PDB can be used as an independent database worker application, it can contain its own data files, but all PDB share CDB control files and log files. The so-called pluggable means that PDB can be plugged into the CDB at any time like USB, and can be unplugged at any time when it is not in use. A maximum of 250 PDB can be inserted in a CDB. In PDB, seedPDB is the template PDB, which provides a template for the newly created PDB, and other PDB can be created and deleted as needed. The pluggable feature can speed up the deployment of the database, and a patch to a CDB can synchronize all updates to all PDB on it.

In versions prior to Oracle 12c, instances and databases can only be one-to-one or many-to-one (RAC,Real Application Clusters, real-time application clusters), that is, only one instance corresponds to one database, or multiple instances correspond to one database. However, in the Oracle 12c version, by introducing CDB and PDB, an instance can correspond to multiple pluggable databases.

Usage scenarios for pluggable databases:

There are many applications in the enterprise that need to use Oracle database. They only use a very small amount of hardware resources, but have to create multiple instances for them.

Some databases that are not very important, packaging requires DBA to spend a lot of effort to maintain

In order to make better use of hardware resources and reduce management overhead, it is necessary to integrate a large number of departmental applications into a few Oracle relational databases for deployment and management.

By deploying multiple databases on a centralized platform while sharing a database instance, the cost can be greatly reduced, that is, less instance loss and arable land storage technology.

If you need only one database in a production environment and do not want to use a pluggable database, you can uncheck the create as Container Database check box during installation and a normal database will be installed.

2. Oracle server

Oracle server is mainly composed of strength and database files, which is often called database management system (Database Management System,DBMS). The composition of the Oracle server is shown below:

In addition to maintaining the instance and database files, the Oracle server also starts the server process and assigns PGA. (Program Area, the whole global area of the program) when the user establishes a connection with the server.

3. Oracle storage structure

The storage structure of Oracle is divided into physical structure and logical structure, which are independent and related to each other. As shown in the following figure:

Physical structure mainly describes the external storage structure of Oracle database, that is, how to organize and manage data in the operating system.

Logical structure mainly describes the internal storage structure of Oracle database, that is, it describes how to organize and manage data in Oracle database from the logical concept. 1) physical structure of Oracle

The physical structure is the operating system physical files used after the creation of the Oracle database. The physical files of the Oracle database are divided into the following two categories:

(1) main documents

① data file: a data file (Data File), usually with a .dbf extension, is a file that physically stores Oracle database data.

Characteristics of data files:

Each data file is associated with only one database

A tablespace can contain one or more data files

A data file can only belong to one tablespace

② redo log file: the redo log file (Redo Log File), which has the extension .log, records all changes to the data and provides a data recovery mechanism to ensure that the database is restored after a system crash or other unexpected occurrence.

In the Oracle database, redo log files are used in groups, and each redo log file group can have one or more redo log files. In the course of work, multiple redo log filegroups are recycled, and when one redo log filegroup is full, it goes to the next log filegroup. The redo log file is used to record database changes and is the user's transaction log.

③ control file: the control file (Control File) has a .ctl extension and is a binary file. There is a lot of information stored in the control file, including the name and location of the data file and the redo log file. Control files are necessary for database startup and operation. When Oracle reads and writes data, it should look up the data file according to the information of the control file.

Because of the importance of control files, a database must have at least two control files. Oracle 12c contains two control files by default, each of which has the same content, thus avoiding the failure to start the database due to the corruption of one control file.

The following key information is recorded in the control file:

Location and size of the data file

Location and size of the redo log file

Database name and creation time

Log serial number; (2) other files

Other files include parameter files, archive log files, password files, and so on.

2) Oracle logical structure

The logical structure of the database analyzes the composition of the database from a logical point of view. The logical structure of Oracle database includes table space, segment, extent, block, schema and so on. As shown in the figure:

(1) Tablespace

Each Oracle database is made up of several tablespaces, and all the content created by users in the database is stored in the tablespace. A tablespace can consist of multiple data files, but a data file can only belong to one tablespace. Unlike the physical structure of data files, tablespaces belong to the logical structure of the database.

In each database, there is a tablespace called "SYSTEM", that is, the system tablespace, and there are also tablespaces such as SYSAUX, UNDO, USERS, and so on, which are created automatically when the database is created. Administrators can create custom tablespaces and assign them to specified users, or they can add and delete data files for tablespaces.

There are basically three types of tablespaces:

① permanent tablespace: data that generally maintains base tables, attempts, procedures, indexes, and so on. SYSTEM, SYSAUX, USERS tablespaces are installed by default

② temporary tablespace: only used to hold data of short-term activities in the system, such as sorted data, etc.

There is generally no need to create temporary and undo tablespaces unless they are transferred to other disks to improve performance.

The purpose of the tablespace is as follows:

① assigns different table spaces to different users and different schema objects to facilitate the operation of users and the management of schema objects.

② can create different data files on different disks, which is helpful to manage disk space, improve Imax O performance, backup and restore data, etc.

Generally speaking, after completing the installation of the Oracle system and creating an Oracle instance, the Oracle system automatically establishes multiple tablespaces such as SYSTEM, SYSAUX, USRS and so on.

Here is a detailed description of SYSTEM tablespaces, SYSAUX tablespaces, TEMP tablespaces, and TEMP tablespaces:

SYSTEM tablespace: data used to store tables and data dictionaries within the Oracle system, such as table names, column names, user names, etc. It is not recommended to store user-created tables, indexes, and other objects in SYSTEM tablespaces.

SYSAUX tablespace: as an auxiliary tablespace of SYSTEM, it is used to store the data of users of various database tools; it is also used to store object data of various modes, such as intelligent agent user DBSNMP, etc. These schemas establish the corresponding objects and store them in the SYSAUX tablespace after the database is installed.

USERS tablespace: typically used as a tablespace for users, you can create a variety of objects, such as tables, indexes, and so on.

TEMP tablespace: a special tablespace used by Oracle systems to store temporary data. For example, when sorting is needed in an operation, the Oracle system temporarily stores the sorted data in the tablespace.

In addition to the tablespaces created by default in the Oracle system, users can create multiple tablespaces based on the schema of the application system and the types of objects to be stored to distinguish between user data and system data.

Create a tablespace data definition language with the following syntax:

SQL > create tablespace benet datafile'/u01/app/oracle/oradata/benet.DBF' size 10m autoextend on

In grammar:

Tablespacename is the tablespace name.

DATAFILE specifies one or more data files that make up the tablespace, separated by commas when there are multiple data files.

Filename is the path and name of the data file in the tablespace.

SIZE specifies the size of the file, kilobytes in K, and megabytes in M.

The AUTOEXTEND clause is used to start or disable automatic extension of data files. If the AUTOEXTEND parameter is set to ON, space exhaustion will automatically expand; when the AUTOEXTEND parameter is set to OFF, it is easy to see that the remaining capacity of the tablespace is 0, resulting in the data cannot be stored in the database.

After the tablespace is created, you can manage the tablespace accordingly, including the following operations.

Adjust the tablespace size. When the data insertion fails and the tablespace is full, you can adjust the tablespace size through the ALTER statement. There are two ways to resize the tablespace.

Method 1: change the size of the data file and indicate the storage path of the data file. The RESIZE keyword is also used to specify the size of the adjusted data file. The code is as follows:

SQL > alter database datafile'/u01/app/oracle/oradata/benet.DBF' resize 50M. Database altered.

Method 2: add a data file to the tablespace. The code to add a new data file to the tablespace is as follows:

SQL > alter tablespace benet add datafile'/ u01 size autoextend no;Tablespace altered.

Change the read and write state of the tablespace. When the data is historical data, only queries are allowed and do not want to be modified so that the tablespace can be set to read-only. READ ONLY indicates that the tablespace is read-only, and READ WRITE indicates that the tablespace is read-write. The specific syntax format is as follows:

SQL > alter tablespace benet read only; Tablespace altered.SQL > alter tablespace benet read write; Tablespace altered.

Delete tablespaces. You can delete the tablespace through the DROP statement, just add the name of the tablespace. The specific syntax format is as follows:

SQL > drop tablespace benet including contents;Tablespace dropped. (2)

A Segment exists in a tablespace and is a logical storage structure of a specified type, consisting of a set of extents. Segments can be divided into four categories: data segment, index segment, fallback segment, temporary period. For example, there is a data segment for each non-clustered table, and all the data of the table is stored in that segment, and for each index there is an index segment.

(3) Zone

The Extent is the smallest unit of disk space allocation. The disk is divided by zone, allocating at least one zone at a time. The zone consists of contiguous blocks. A segment mainly consists of one or more zones, and when a segment is created, it contains at least one zone. When all the space in the segment is fully used, the system automatically assigns a new area to the segment. A zone cannot exist across data files, it can only exist in one data file.

(4) data block

Data block (Data Block) is the smallest data organization unit in the database. The data in the Oracle database is stored in blocks. A data block is the smallest storage unit that an Oracle server can read or write. The Oracle server manages the storage space of data files in blocks. The value range of the data block is 2~64KB, and its default size is related to the Oracle version.

(5) Mode

A Schema is a collection of database objects (also called schema objects). Schema objects include tables, views, indexes, synonyms, sequences, procedures, packages, and so on. Each time a user is created, Oracle automatically creates a pattern that is the same as the user name, so the pattern is also called user mode. After the user logs in, the default access is the database object in the schema with the same name as his or her own.

4. Oracle memory structure

Memory structure is the most important part of Oracle database system, and memory is also the first factor that affects database performance.

The main contents of Oacle memory storage:

Program code

Information about connected sessions, including all current active and inactive sessions

Relevant information necessary for the program to run, such as the query plan

Information that is communicated and shared between Oracle processes, such as locks

According to the way memory is used, the memory of Oracle database can also be divided into SGA, PGA, and UGA (User Global Area, user global area).

SGA: the shared memory area of the instance that is accessible to all users. Data blocks, transaction logs, data dictionary information, and so on are all stored in SGA.

PGA: a class of unshared memory that is dedicated to a specific server process and can only be accessed by that process.

UGA: the area of memory where session state is stored for the user process. Depending on whether the user database is configured in dedicated server mode or shared server mode, UGA can be part of SGA or PGA. It stores data for user sessions. Next, let's focus on SGA and PGA:

1) SGA

The SGA of the Oracle instance stores database information and is shared by multiple database processes. When the database instance starts, SGA's memory is automatically allocated. SAG is the largest area of server memory in the database, and it is also an important index that affects the performance of the database. SGA can be divided into shared pools, data buffers, redo log buffers, large pools and Java pools according to their different functions.

① shared Pool

Shared pool is the memory area used for parsing, compiling and executing SQL and PL/SQL programs. The shared pool consists of a library cache and a data dictionary cache.

The data dictionary cache contains tables, indexes, column definitions, permission information, and other database object definitions obtained from the data dictionary. If Oracle caches these information, it will undoubtedly shorten the response time of the query. ② data buffer

The data buffer is used to store data read from disk data files for sharing by all users. When you modify the data, you should first take the data from the data file and store it in the data buffer. The modified data and the inserted data are stored in the data buffer, and the data is written to the data file only when the modification is completed and other conditions are met.

When processing a query, the Oracle server process first looks for the existence of the required data blocks in memory. If the desired block is not found in the data buffer, the server process reads the block from the data file and saves it in the buffer. When subsequent requests need to read these blocks, they can be found in memory, so these requests do not need to be read from disk, thus improving the reading speed. The size of the data buffer has a direct impact on the reading speed of the database.

③ redo log buffer

When users perform operations such as INSERT, UPDATE, DELETE, CREATE, ALTER, DROP, etc., the data changes. The changed data is written to the redo log buffer before it is written to the data cache, and the data before the change is also put into the redo log cache, so that Oracle knows which resources need to be committed and which resources need to be withdrawn when the data is recovered. The log buffer has less impact on the performance of the database than the data buffer.

④ big pool

In SGA, a large pool is an optional buffer that the administrator can configure as needed. Large pools are also needed as buffer space in the process of large-scale input, output and backup, such as big data operation, database backup and recovery.

⑤ Java Pool

The Java pool is also an optional buffer in SGA, but when you install Java or use a Java program, you must set up the Java pool to compile instructions written in the Java language.

2) PGA

PGA is not part of the instance, it contains the data and control information required by a single server process or a single background process. PGA is automatically allocated when the user process connects to the database and creates a session, and the partition retains the memory required by each user process connected to the Oracle database. After a user ends the session, the PGA is released.

5. Oracle process structure

There are several different types of processes in Oracle: user processes, server processes, and background processes.

User process: started when a database user requests to connect to the Oracle server

Server process: starts when the user establishes a session and connects to the Oracle instance

Background process: starts when the Oracle instance is started

The user process is a program that needs to interact with the Oracle server process. A user process is created when a database user runs an application ready to send a request to the database server. For example, when a user starts the database tool Sqlplus, the system will automatically establish a user process.

The server process is used to process requests from the user process connected to the instance. When the user establishes a connection to the database, the server process is generated. The server process communicates with the user process and requests services for the connected users. The server process interacts with the Oracle database directly to achieve the purpose of calling and returning results. The server process can handle the requests of one user process, and it can also handle the requests of multiple user processes.

In the Oracle database, in order to make the system performance better coordinate multiple users, some additional processes used in the instance system are called background processes. These background processes exist in the operating system and start automatically when the instance starts. Five of these processes must be started, or the database instance cannot be started. These five important and necessary background processes are process monitoring (Process Monitor,PMON) process, system monitoring (System Monitor,SMON) process, data writing (Database Writer,DBWR) process, log writing (Log Writer,LGWR) process, and checkpoint (Check Point,CKPT) process.

1) PMON process

The PMON process performs resource cleanup after an unexpected disconnection to the user, including the following tasks:

Release all currently pending locks

Roll back the user's current transaction

Release the resources currently used by the user

Monitor server processes and other background processes and restart them in case of failure; 2) SMON processes

The SMON process performs the following tasks:

Perform instance recovery when the instance is started. Instance recovery includes three steps:

① rolls forward to recover unwritten data files but data that has been logged into online log files

③ rollback for committed transactions

Organize the free space of data files

The DBWR process performs the following tasks:

Manage data buffers so that free buffers can be found to read data from data files

Write all modified buffer data to the data file

Use the LRU algorithm to keep recently used blocks in memory

Optimize disk read and write by delaying writes; 4) LGWR process

The LGWR process is responsible for writing log data from the redo log buffer to the log filegroup. When the database is running, if the data is modified, the log information is generated, and the log information is first generated in the redo log buffer. This buffer operates according to the principle of "first-in, first-out". The log information satisfies a certain condition that the log data is written to the log file by the LGWR process. The system usually has multiple log files, and the log writing process writes data to the file in a circular manner.

5) CKPT process

The CKPT process is the mechanism that ensures that all modified blocks in the data buffer are written to the data file. When the checkpoint is completed, the CKPT process is responsible for updating the data file header and control file, and saving the checkpoint information to ensure the synchronization of the database log file and the data file. When the database is restored, you only need to find the last checkpoint saved by CKPT, and then you can use it to determine the starting location of the recovery data in the log file, and then re-execute the logging that followed.

6) ARCn process

The ARCn process, the Archive Log process, is an optional process that is available only when log archiving is opened. The main role of this process is to copy full online log files to the archive directory when a log switch occurs.

2. Basic operation of CDB and PDB

Unlike previous versions of Oracle, Oracle 12c can be used as a single database (by unchecking the "create as container database" check box during reinstallation), or several pluggable PDB databases can be provided according to the needs of the enterprise. Each PDB can be maintained by a different DBA. The basic maintenance of CDB and PDB is described below.

[oracle@oracle] $source .bash _ profile [oracle@oracle ~] $sqlplus / as sysdba SQL*Plus: Release 12.2.0.1.0 Production on Tue Jan 7 14:58:04 2020Copyright (c) 1982, 2016, Oracle. All rights reserved.Connected to:Oracle Database 12c Enterprise Edition Release 12.2.0.1.0-64bit ProductionSQL > startup; ORACLE instance started.Total System Global Area 1660944384 bytesFixed Size 8793448 bytesVariable Size 1056965272 bytesDatabase Buffers 587202560 bytesRedo Buffers 7983104 bytesDatabase mounted.Database opened.SQL > SQL > show con_name; CON_NAME--CDB$ROOT SQL > SQL > show pdbs CON_ID CON_NAME OPEN MODE RESTRICTED- 2 PDB$SEED READ ONLY NO 3 ORCLPDB MOUNTED SQL > SQL > alter pluggable database orclpdb open Pluggable database altered.SQL > SQL > alter session set container=orclpdb; Session altered.SQL > SQL > show con_name; CON_NAME--ORCLPDBSQL >

Switch from CDB to PDB and the related operations are as follows:

SQL > show con_name; CON_NAME--CDB$ROOTSQL > SQL > alter session set container=orclpdb; Session altered.SQL > SQL > show con_name; CON_NAME--ORCLPDBSQL > SQL > shutdown immediate; Pluggable Database closed.SQL > SQL > startup; Pluggable Database opened.SQL > SQL > alter session set container=cdb$root Session altered.SQL > SQL > show con_name; CON_NAME--CDB$ROOTSQL >

From the above operation, you can find that you can manage PDB in CDB, for example, in CDB, you can set PDB data to open state by using the command "alter pluggable database orclpdb open". Of course, it can also be maintained in PDB, such as the "shutdown immediate" command and the "startup" command to close and open the PDB database, respectively. Switching between CDB and PDB is also very convenient, as long as you execute the "alter session set container=xxx" command.

There are two ways to connect to a pluggable data PDB, one is to execute the command "sqlplus / as sysdba" to enter CDB, and then to switch to PDB; through the "alter session set container=xxx" command. The other is to execute the "sqlplus sys/oracle@orclpdb sa sysdba" command to enter the PDB database directly, where orclpdb is the name of the pdb container, and add the following to the / u01/app/oracle/product/12.2.0/dbhome_1/network/admin/tnsnames.ora file:

[oracle@oracle ~] $vim / u01/app/oracle/product/12.2.0/dbhome_1/network/admin/tnsnames.ora # Generated by Oracle configuration tools.LISTENER_ORCL = (ADDRESS = (PROTOCOL = TCP) (HOST = oracle) (PORT = 1521) # Generated by Oracle configuration tools.LISTENER_ORCL = (ADDRESS = (PROTOCOL = TCP) (HOST = oracle) (PORT = 1521) ORCL = ORCL = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = oracle) (PORT) = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)-ORCLPDB = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = Oracle) (PORT = 1521) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orclpdb)) III. User management

When creating a new database, Oracle creates some default database users, such as SYS, SYSTEM, and so on. Both SYS and SYSTEM users are administrative users of Oracle. If you choose to install the sample database during installation, the HR user is automatically created, and the HR user is a demonstration user of the Oracle database, and you can import other sample databases as needed. The sample database contains some sample tables for test demonstration. Here's a brief introduction to SYS, SYSTEM, and custom users.

1 、 SYS

SYS user is a super user in Oracle, which is mainly used to maintain system information and manage instances. All data dictionaries and views in the database are stored in the SYS schema. The data dictionary stores all the information used to manage database objects and is a very important system information in Oracle database. SYS users can only log in to the database system in the SYSOPER or SYSDBA role.

2 、 SYSTEM

The SYSTEM user is the default database administrator in Oracle and has DBA privileges. This user mode stores the internal tables and views used by the Oracle management tools. Users, permissions, and storage of Oracle databases are usually managed by SYSTEM users, and it is not recommended to create user tables in SYSTEM schema. SYSTEM users cannot log in to the system in the role of SYSOPER or SYSDBA, but can only log in by default (database authentication).

3. Custom user

Oracle 12c supports the creation of custom users, which are different from previous versions due to the introduction of PDB. In CDB mode, there are two types of users: public users and local users. Public users can be used in CDB and PDB, while local users can only be used in PDB. In a CDB environment, the creation of local users is not allowed. Oracle states that when creating a public user in CDB, the user name must start with clocked #.

In general, for security reasons, different users need different access to their data tables, so different users need to be created. The CREATE USER command in Oracle is used to create a new user. Each user has a default space and a temporary tablespace. If not specified, Oracle sets USERS as the default tablespace and TEMP as the temporary tablespace. The syntax for creating a user is as follows:

1) log in to CDB of orcl database as system user, create user tom with password 123, default tablespace is users, temporary tablespace is temp, enable tablespace limit, next login change password SQL > create user c##tom identified by 123default tablespace users temporary tablespace temp quota unlimited on users password expire;User created.2) change tom user password to 123456SQL > alter user c##tom identified by 123456suser altered.3) delete unused account tomSQL > drop user c##tom cascade;User dropped. IV. Database authority management

Permission is the right to execute some type of SQL statement to access other user database objects. In Oracle, permissions are divided into two categories: system permissions and object permissions.

1. System permissions

System permission refers to the right to perform a system-level operation in a database, or to perform an operation on a certain class of objects. For example, the right to create a tablespace in a database, or the right to create a table in a database, is a system permission. An example of system permissions is as follows:

Common system permissions are as follows:

CREATE SESSION: connecting to a database

CREATE TABLE: creating tables

CREATE VIEW: creating view

CREATE SEQUENCE: creating sequenc

After a new user is created, it is preferred to grant him CREATE SESSION permission to log in to the database.

2. Object permissions

Object permissions are the rights to perform operations on a particular schema object. Object permissions can only be set and managed for schema objects, including tables, views, sequences, stored procedures, and so on. As shown in the following figure:

There are two ways for Oracle database users to gain permissions: ① grants permissions directly to users, and ② grants permissions to roles, which in turn grant roles to one or more users. Using roles makes it easier and more efficient to manage permissions. So the database administrator grants permissions to users by using roles, rather than directly. Many roles are predefined in Oracle database system, among which the most commonly used roles are CONNECT role, RESOURCE role, DBA role and so on.

The system predefined roles commonly used in Oracle are as follows:

CONNECT: have permission to connect to the database

RESOURCE: have permissions to create tables, triggers, procedures, etc.

DBA: database administrator role with the highest permissions to manage the database; a user with the DBA role can authorize any other user or even other DBA permissions, which is dangerous, so do not easily grant this role

The newly created user must be granted certain permissions to operate on the related database. Authorization is through the CRANT statement, and de-authorization is through the REVOKE statement.

1) create bob account, authorize and revoke authorization syntax example SQL > alter session set container=orclpdb; Session altered.SQL > create user bob identified by 123456; User created.SQL > grant connect,resource to bob; Grant succeeded.SQL > revoke connect,resource from bob; Revoke succeeded.

The design principles of database user security are as follows:

Where do the database users go first according to the principle of minimum allocation

Database users can be divided into four types: management, application, maintenance and backup.

Sys and system users are not allowed to build database application objects

It is forbidden to grant dba permissions to ordinary users

Query permissions can only be opened to query users.

Force the password to be changed when a new user logs in to the database for the first time

General program developers only need to grant the roles of CONNECT and RESOURCE. In particular, granting these two roles involves granting users unrestricted access to the default tablespace.

-this is the end of this article. Thank you for reading-

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