This preface contains:
Changes in Oracle Database Release 21c
Changes in Oracle Database 21c:
The following features are new in Release 21c:
ALTER TABLE MOVE for Partitioned and Subpartitioned Heap-Organized Tables
You can move all the partitions and subpartitions of a partitioned heap-organized table with a single
ALTER TABLE MOVE statement.
With release 21c, you can use the
shrink_clause of the
ALTER TABLE statement to modify SecureFile LOB segments.
Standby CDB continuity
You can use the
pdb_managed_recovery clause of the
ALTER PLUGGABLE DATABASE statement to recover a PDB in instances where the PDB is within a physical standby CDB.
Auditing for Oracle XML DB HTTP and FTP Services
You can use the
PROTOCOL component of
CREATE AUDIT POLICY to audit FTP and HTTP messages.
Unified Audit Policies Enforced on the Current User
The unified audit policy created with
CREATE AUDIT POLICY becomes active immediately for the current session and subsequent sessions as soon as the
AUDIT POLICY statement is executed.
New DIRECTORY_DATASTORE Data Store Type for Oracle Text
You can use a new data store type called
DIRECTORY_DATASTORE instead of the
FILE_DATASTORE data type.
DIRECTORY_DATASTORE provides greater security because it enables file access to be based on directory objects.
FILE_DATASTORE is deprecated.
New NETWORK_DATASTORE Data Store Type for Oracle Text
You can use a new data store type called
NETWORK_DATASTORE instead of the
URL_DATASTORE data type.
NETWORK_DATASTORE provides greater security because it enables file access to be based on directory objects.
URL_DATASTORE is deprecated.
Automatic In-Memory Management Enhancements
Automatic In-Memory Management enables, populates, evicts, and recompresses segments without user intervention.
AUTO in the
inmemory_memcompress clause to instruct the database to manage the segment.
Oracle Blockchain Table
Blockchain tables enable you to implement a centralized ledger model where all participants in the blockchain network have access to the same tamper-resistant ledger. You can create blockchain tables with the
CREATE TABLE statement.
Active Data Guard - Standby Result Cache
The result cache in an Active Data Guard standby database is utilized to cache results of queries that were run on the physical standby database. You can enable
STANDBY in the
In-Memory Full Text Columns
You can apply the
INMEMORY TEXT clause to non-scalar columns in an In-Memory table. This clause enables fast In-Memory searching of text, XML, or JSON documents using the
JSON_TEXTCONTAINS () operators .
You can create SQL Macros (SQM) to factor out common SQL expressions and statements into reusable, parameterized constructs that can be used in other SQL statements. SQL macros can either be scalar expressions, typically used in
HAVING clauses, to encapsulate calculations and business logic or can be table expressions, typically used in a
SQL macros increase developer productivity, simplify collaborative development, and improve code quality.
Unicode 12.1 Support
Oracle Database 21c complies with version 12.1 of the Unicode Standard.
Bitwise Aggregate Functions
The new aggregate functions
BIT_XOR_ADD enable bitwise aggregation of integer columns and columns that can be converted or rounded to integer values.
New Analytical and Statistical Aggregate Functions
New analytical and statistical aggregate functions are available in SQL:
CHECKSUMcomputes the checksum of the input values or expression.
KURTOSIS_SAMP, measure the tailedness of a data set where a higher value means more of the variance within the data set is the result of infrequent extreme deviations as opposed to frequent modestly sized deviations. Note that a normal distribution has a kurtosis of zero.
SKEWNESS_SAMP, are measures of asymmetry in data. A positive skewness is means the data skews to the right of the center point. A negative skewness means the data skews to the left.
All of these new aggregate functions support the keywords
ANY_VALUE, a function to simplify and optimize the performance of
GROUP BY statements, returns a random value in a group and is optimized to return the first value in the group. It ensures that there are no comparisons for any incoming row and eliminates the necessity to specify every column as part of the
GROUP BY clause.
With these additional SQL aggregation functions, you can write more efficient code and benefit from faster in-database processing.
PREDICTION Function Syntax
PREDICTION functions have a new
_ordered syntax for scoring a model that requires ordered data, such as a Multivariate State Estimation Technique - Sequential Probability Ratio Test (MSET-SPRT) model:
Enhanced SQL Set Operators
The SQL set operators now support all keywords as defined in ANSI SQL. The new operator
ALL] is functionally equivalent to
ALL]. The operators
INTERSECT now support the keyword
Database In-Memory External Table Enhancements
INMEMORY clause is supported at the table level and partition level of a partitioned external table or hybrid external table. For hybrid tables, the table-level
INMEMORY attribute applies to all partitions, whether internal or external.
New JSON data type
JSON is a new SQL and PL/SQL data type for JSON data. It provides a substantial increase in query and update performance compared to textual JSON.
JSON Scalar Allowed at Top Level of JSON Document (RFC 8259 Support)
JSON documents in Oracle Database can now have a top-level JSON scalar value. Previously they had to have a JSON object or array value.
New Oracle SQL Function JSON_TRANSFORM
You can use SQL function
JSON_TRANSFORM to update parts of a JSON document without having to parse and rebuild it.
Enhanced Analytic Functions
Analytical window functions now supports the
EXCLUDE options of the SQL standard window frame clause. The
query_block clause of the
SELECT statement now supports the
window_clause, which implements the window clause of the SQL standard table expression as defined in the SQL:2011 standard.
Enhanced Database Availability with Zero Downtime to Switch Over to an Updated PKCS#11 Library
Starting with this release, Oracle Database can switch over to an updated PKCS#11 library without incurring any system downtime.
You can use the new
ADMINISTER KEY MANAGEMENT SWITCHOVER LIBRARY FOR ALL CONTAINERS statement to enable an Oracle database to switch over from the PKCS#11 library that it is currently using to the updated PKCS#11 library.
Enhanced Double Parity Protection for Flex and Extended Disk Groups
You can use double parity protection for write-once files in a Oracle ASM Flex Disk Group which provides greater protection against multiple hardware failures.
Oracle ASM Flex Disk Group Support for Cloning a PDB in one CDB to a New PDB in a Different CDB
You can clone a PDB in a CDB to a new PDB in a different CDB using the
ALTER PLUGGABLE DATABASE.
File Group Templates
With file group templates you can customize and set default file group properties for automatically created file groups, enabling you to customize file group properties that are inherited by a number of databases.
TEMPLATE option of the
Automatic Index Optimization
You can enable Automatic Data Optimization (ADO) functionality to provide compression and optimization capability on indexes using the
CREATE INDEX and
Gradual Database Password Change for Applications
Starting with Release 21c, an application can change its database passwords without an administrator having to schedule downtime.
You can enable gradual database password rollover period by setting a non-zero value to the
PASSWORD_ROLLOVER_TIME user profile parameter using
CREATE PROFILE or
After you set the time for the gradual password rollover period, you can use the
ALTER USER statement to change the user's password and propagate the new password to all clients before the
Minimum Password Length Enforcement for All PDBs
Starting with this release, you can enforce a minimum password length on all PDBs by setting a mandatory profile in the CDB root using
The following features are deprecated in Release 21c, and may be desupported in a future release:
Traditional auditing is deprecated in Oracle Database 21c. Oracle recommends that you use unified auditing, which enables selective and more effective auditing inside Oracle Database.
The Oracle Text type
URL_DATASTOREis deprecated. Oracle recommeds that you replace
NETWORK_DATASTORE, which uses ACLs to control access to specific servers.
The Oracle Text type
FILE_DATASTOREis deprecated. Oracle recommends that you replace
FILE_DATASTOREindexes with the
DIRECTORY_DATASTOREindex type, which is available starting with Oracle Database 21c.
DIRECTORY_DATASTOREprovides greater security because it enables file access to be based on directory objects.
Starting with Oracle Database 21c, older encryption and hashing algorithms contained within
DBMS_CRYPTOare deprecated. These are
RC4. To meet your security requirements, Oracle recommends that you use more modern cryptography algorithms.
The following features are desupported in Oracle Database Release 21c:
Oracle Database 21c uses a multitenant architecture. Starting in this release, you can no longer create or upgrade to non-CDBs. The word "database" now means either a CDB or PDB.
Starting with Oracle Database 21c, several XML Database (XDB) features are desupported. The Oracle SQL function XMLRoot is desupported. Use SQL/XML function XMLSerialize() with a version number instead.
For a full list of desupported features for Release 21c, please see the Oracle Database Upgrade Guide.