In this post, we will discuss the Flashback technology in Oracle, its architecture, Oracle Flashback query, the syntax to use Oracle Flashback query What is Flashback technology in Oracle? Oracle has introduced Flashback Technology that lets you view past states of database objects or return database objects to a previous state without using point-in-time media […]
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What is UNDO? How to monitor the usage of UNDO tablespace (1)Check allocated space and free space for UNDO tablespace. SELECT /* + RULE */ df.tablespace_name “Tablespace”,df.bytes / (1024 * 1024) “Size (MB)”,SUM(fs.bytes) / (1024 * 1024) “Free (MB)”,Nvl(Round(SUM(fs.bytes) * 100 / df.bytes),1) “% Free”,Round((df.bytes – SUM(fs.bytes)) * 100 / df.bytes) “% Used”FROM dba_free_space fs,(SELECT
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Why Local Undo is required We have global or shared undo for the entire CDB till 12c R1. With shared undo, before performing operations such as (cold) clone or unplug, it is necessary for the database to check for any uncommitted transactions in the source PDB. This is to avoid problems with transactional consistency in
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In this post, we will see the Script to check locks in oracle database, how to check locks in oracle, how to check lock on table in oracle Locks is a process in the Oracle database through which it maintains consistency and concurrency. So they keep coming and going. We generally don’t need to worry
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We can change the column datatype in a table using alter table modify column in oracle ALTER TABLE table_name MODIFY column_name <action>; Action can be many things like(a) change the data type(b) Shorten or widen the data type(c) Change the default value(d) Change to allow null or not nulls(e) Column Visibility(d) Virtual Column ModificationLet’s start
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What is Supplemental Logging in Oracle Oracle Redo log file has the record of all the operations performed in the database by default or automatically. So Redo log files are generally used for instance recovery and media recovery. They are also used for Physical standby or physical replication. But by default Oracle redo logs files
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