Relational Databases

  As you know, the In-Memory feature can be enabled or disabled at the column level: SQL > create table usef.tb(c1 number,c2 number,c3 number,c4 number,c5 number,c6 number); Table created. SQL > ALTER TABLE usef.tb INMEMORY NO INMEMORY (c1,c2); Table altered. SQL > SELECT TABLE_NAME, COLUMN_NAME, INMEMORY_COMPRESSION FROM V$IM_COLUMN_LEVEL WHERE TABLE_NAME = 'TB' ORDER BY COLUMN_NAME; TABLE_NAME COLUMN_NAME INMEMORY_COMPRESSION ---------- --------------- -------------------------- TB C1 NO INMEMORY TB C2 NO INMEMORY TB C3 DEFAULT TB C4 DEFAULT TB C5 DEFAULT TB C6 DEFAULT 6 rows selected. SQL > select inmemory from dba_tables where TABLE_NAME = 'TB' ; INMEMORY -------- ENABLED When a table contains many columns, the above command text can become lengthy. Therefore, this command requires more flexibility to...

  In Oracle 21c, a function named   COMPARE_EXPLAIN   was added to   DBMS_XPLAN , which allows comparing the explain plans of two SQL statements. At the end of the report (in the "Comparison Results" section), the differences between the two plans are shown. See the example below. SQL > create table mytbl as select * from dba_objects; Table created SQL > create index ind1_object_id on mytbl(object_id); Index created SQL > explain plan set statement_id = ‘Plan1’ for select /*+ full(mytbl) */ * from mytbl where object_id = 9 ; Explained SQL > explain plan set statement_id = ‘Plan2’ for select /*+ index(mytbl) */ * from mytbl where object_id = 9 ; Explained SQL > VARIABLE varvar1 varchar2( 9000 ) SQL > exec :varvar1 : = dbms_xplan.compare_explain(‘Plan1′,’Plan2’); PL / SQL procedure successfully completed. SQL > select :varvar1 from dual; COMPARE PLANS REPORT ——————————————————————————————— Current user ...

  In Oracle 23ai, it is possible to apply patches to the Grid software using the gridSetup.sh script through a wizard-based graphical interface. This process can also be performed with zero downtime. In this guide, we aim to apply Release Update 23.6 to Grid Infrastructure version 23.5. Currently, Grid Infrastructure 23.5 is running: [grid @OL810 ~ ]$ sqlplus "/as sysasm" SQL * Plus: Release 23.0 .0 .0 .0 – for Oracle Cloud and Engineered Systems on Wed Nov 27 12 : 57 : 14 2024 Version 23.5 .0 .24 .07 Copyright © 1982 , 2024 , Oracle. All rights reserved. Connected to : Oracle Database 23 ai Enterprise Edition Release 23.0 .0 .0 .0 – for Oracle Cloud and Engineered Systems Version 23.5 .0 .24 .07 SQL > To apply the patch, the Grid Infrastructure software version 23.6 must first be installed as  software only . [root@OL810 ~]# /grid/ 23.6 /root.sh Performing root user operation. The following environment variables are set as : ORACLE_OWNER= grid ORACL...