Anju Garg

Author

Recently I wanted to create a policy managed database in my 12.1.0.2 flex cluster setup, but free servers are not available. Hence I had to unregister an administrator managed RAC database (amdbh12) to make the servers available. Having completed my testing, I dropped the policy managed database and then wanted to drop the database amdbh12 using DBCA. It was then… Continue Reading →

All Things Oracle Full Articles

Introduction Oracle Database 10g Release 1 introduced Automatic Storage Management (ASM), a new framework for managing Oracle database files. ASM provides a foundation for highly efficient storage management with direct I/O, redundancy, striping and load balancing. Files stored on ASM are evenly distributed across disks in a disk group and mirrored according to the policies defined in the disk group…. Continue Reading →

10g, 11g, 12c, All Things Oracle Full Articles

Cloning of a Pluggable Database (PDB) in Oracle Multitenant is a great feature and is very useful. Oracle Database 12c Release 1 has introduced various enhancements to the cloning of Pluggable Databases to overcome the limitations imposed by the initial release of Oracle Database 12c (12.1.0.1). In Oracle 12.1.0.2c: PDBs can be hot cloned, i.e. you don’t need to put the source PDB… Continue Reading →

12c, All Things Oracle Full Articles

In the initial release of Oracle 12c (12.1.0.1c), a non-Container Database (non-CDB) could be converted to a pluggable database (PDB) using any of the following methods: Using DBMS_PDB Using datapump (expdb, impdp) Using GoldenGate replication The 12.1.0.2 patchset has introduced the ability to clone a remote non-CDB as a PDB directly over the network. Remote Cloning of a Non-CDB is a… Continue Reading →

12c, All Things Oracle Full Articles

Offline backups (also known as Cold or consistent backups) are taken when the database is in a consistent state, i.e. the database has been shut down with the SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL commands. As part of a consistent shutdown, redo has been applied to the data files and the System Change number (SCN) in the data file… Continue Reading →

All Things Oracle Full Articles

As data in tables is updated and / or deleted, pockets of empty space can be created, leading to fragmented free space. This free space is wasted space as it is insufficient to hold new data. Moreover, it can impact performance of the database as a higher number of sparsely-populated blocks need to be visited. Oracle 11g introduced online segment… Continue Reading →

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Oracle 12c has introduced Flex Clusters which use hub-and-spoke technology, allowing the cluster to scale much beyond the pre-12c clusters as it requires: Fewer network interactions between nodes in the cluster, and : Less contention for key Clusterware resources like OCR and voting disks. A Flex Cluster has two types of nodes: Hub Nodes and Leaf Nodes. Hub Nodes These… Continue Reading →

12c, All Things Oracle Full Articles

In an earlier article, I discussed Automatic big table cache (ABTC) which is a new feature introduced in Oracle Database 12.1.0.2c. Automatic big table cache is an optional section of the buffer cache reserved for storing large objects. It tracks only big tables and automatically caches scanned big objects in big table cache thereby avoiding direct path reads. It caches… Continue Reading →

12c, All Things Oracle Full Articles

Serial direct path reads were first introduced in Oracle 11g to prevent wiping out a large number of buffers from the buffer cache by a serial large table scan. As a result, big tables accessed via serial Full Table Scans bypass the Buffer Cache and read data from the Data Files into the users’ Program Global Area (PGA). This prevents flooding… Continue Reading →

12c, All Things Oracle Full Articles

Prior to Oracle Database 12c, an ASM instance ran on every node in the cluster and ASM Cluster File System (ACFS) Service on a node connected to the local ASM instance running on the same host to fetch the required metadata. If the ASM instance on a node were to fail, then ACFS file systems could no longer be accessed… Continue Reading →

12c, All Things Oracle Full Articles