Voting disks manage information about node membership. Each voting disk must be accessible by all nodes in the cluster for nodes to be members of the cluster1. You can store OCR and voting disks on Oracle Automatic Storage Management (Oracle ASM)2. If it is stored in ASM, no need to configure manually as the files … Read more
Oracle Clusterware includes three components: voting disks, Oracle Cluster Registry (OCR), and Oracle Local Registry (OLR). ■ Voting disks manage information about node membership. Each voting disk must be accessible by all nodes in the cluster for nodes to be members of the cluster. ■ OCR manages Oracle Clusterware and Oracle RAC database configuration information. … Read more
Enqueues are locks that coordinate access to database resources. This event indicates that the session is waiting for a lock that is held by another session. The V$EVENT_NAME view provides a complete list of all the enq: wait events. TM enqueue: The most common reason for waits on TM locks tend to involve foreign key … Read more
This wait indicates that we are waiting for a read operation which reads a number of contiguous blocks from disk. In most cases this indicates that there is some form of full scan (index fast full or full table scan) involved. This event signifies that the user process is reading buffers into the SGA buffer … Read more
This event signifies that the user process is reading a buffer into the SGA buffer cache and is waiting for a physical I/O call to return. A sequential read is a single-block read. DB file sequential reads wait event comes under the User I/O wait class. In any busy system this is one of the … Read more
Overview of Inventory: The inventory is a very important part of the Oracle Universal Installer. This is where OUI keeps all information regarding the products installed on a specific machine. There are two inventories : 1. The inventory in the ORACLE_HOME (Local Inventory) 2. The central inventory directory outside the ORACLE_HOME (Global Inventory) At startup, … Read more
TX lock contention is an application coding, design and usage problem and can ONLY be fixed by changing application code with more frequent and explicit COMMIT statements and any other minor code changes. Oracle Support cannot fix TX lock wait issues other than helping to identify the objects and commands causing the waits. This wait … Read more
In case if we want to identify duplicates rows of a table and want to remove them from a table. Below are the command which will identify and remove the duplicare rows from a Table. 1.) Identify duplicates Here 251 duplicates exist – these can be deleted with command below : 2.) Removing the Rows … Read more
Oracle uses two different index architectures: b-Tree indexes and bitmap indexes. Cluster indexes, bitmap join indexes, function-based indexes, reverse key indexes and text indexes are all just variations on the two main types. b-Tree is the “normal” index . The “-Tree” in b-Tree A b-Tree index is a data structure in the form of a … Read more
What is a data block corruption? Data block corruptions occur whenever data is not in its expected state. Data Block corruptions are one of the common source of database outages. A database block is corrupted when its content has changed from what Oracle Database expects. The block may have contents that are not internally consistent, … Read more