Read-Only Session in Oracle 23ai

By -

 One of the new parameters introduced in Oracle 23ai is the read_only parameter:

SQL> show parameter READ_ONLY
NAME  TYPE        VALUE    
----- ----------- -------- 
read_only                            boolean     FALSE

This parameter can only be configured at the session level. Setting this parameter to true disables the execution of DML and DDL statements within the session:

SQL> alter system set read_only=true scope=spfile;
ORA-32017: failure in updating SPFILE
ORA-02065: illegal option for ALTER SYSTEM
SQL> alter session set read_only=true;
Session altered.
SQL> delete tbl1;
ORA-28193: Can perform read operations only
SQL> drop table tbl1;
ORA-28193: Can perform read operations only

If a transaction is active within the session, enabling this parameter is not allowed:

SQL> delete tbl1;
1 row deleted.

SQL> alter session set read_only=true;
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-65023: active transaction exists in container

Comments

Post a Comment

Popular posts from this blog

Oracle 21c Enhancements for TTS Export/Import

By -
  In Oracle version 21c, new features have been introduced for transportable tablespace (TTS) export/import. This article explores these capabilities in detail. Improvement 1: Parallel Execution of TTS Export/Import In Oracle 19c, TTS export/import operations could not be executed in parallel, as demonstrated by the following: Connected to: Oracle Database 19c Enterprise Edition Release 19.0 .0 .0 .0 – Production ORA-39002: invalid operation ORA-39047: Jobs of type TRANSPORTABLE cannot use multiple execution streams. Oracle addressed this limitation in version 21c, enabling parallel execution for TTS export/import: [oracle@oLinux7 ~]$ expdp directory=drm dumpfile=TTS_DUMP%U.dmp transport_tablespaces=tbs1,tbs2 transport_full_check= y parallel= 2 Export: Release 21.0 . 0 . 0 . 0 – Production on Tue Oct 12 06 : 48 : 54 2021 Version 21.3 . 0 . 0 . 0 Processing object type TRANSPORTABLE_EXPORT/STATISTICS/TABLE_STATISTICS Processing object type TRANSPORTABLE_EXPOR...
Read more

Oracle 23ai — Speed up IMPDP Using NOVALIDATE Constraints

By -
  When executing the   IMPDP   command, some operations do not support parallel execution. Creating constraints is one such operation. Oracle must validate the current data in the table before creating a constraint, which requires a full table scan for each validation. This process can be very time-consuming. Consider the following constraints: ALTER TABLE VAHID.MYTB ADD CONSTRAINT CHECK1 CHECK (col3 > 50 ); ALTER TABLE VAHID.MYTB ADD CONSTRAINT CHECK2 CHECK (col9 IN ( 5 , 15 )); We drop the  MYTB  table and recreate it using a dump file: SQL > drop table mytb; Table dropped. W -1 Processing object type TABLE_EXPORT / TABLE / TABLE_DATA W -1 . . imported "VAHID"."MYTB" 19 GB 337830912 rows in 83 seconds using external_table W -1 Processing object type TABLE_EXPORT / TABLE / CONSTRAINT / CONSTRAINT W -1 Completed 2 CONSTRAINT objects in 208 seconds As shown, creating the two constraints ta...
Read more

Staging Tables in Oracle 23ai

By -
  As you may know, using   staging tables   is a common practice in   Data Warehouse   environments, primarily during the data loading process into the   Warehouse Database . Typically, raw data received from   source databases   is first loaded into a temporary area, referred to as   staging tables . After cleansing inconsistent and invalid data and transforming it into a standard format, the cleaned data is stored in the final operational tables. In addition to initial data loading,   staging tables   are also used for updates and are often truncated before reuse. In   Oracle 23ai , a new minor feature has been introduced for this purpose, allowing users to create tables specifically designed as   staging tables . This is achieved by adding the   FOR STAGING   clause to the   CREATE TABLE   statement. Creating Staging Tables Using the   FOR STAGING   clause, staging tables can be created as ...
Read more