Mohammad Samad

Author's posts

Oct 02 2020

Oracle Database Upgrade Manually from 12.1 to 19.3

This article provides an overview of upgrading an existing non-CDB database from Oracle 12c to Oracle 19c. Upgrades can be very complicated, so this is highly recommended to read the oracle provided manual and test thoroughly before considering an upgrade of a production environment. Oracle Database Upgradation Manual – Read More. Upgrade Path for Oracle …

Continue reading

Oct 02 2020

Upgrade Oracle Enterprise Linux (OEL) 6 to OEL 7

In this article, we will discuss how can upgrade Oracle Linux from 6 to 7 on VM. We are planning to upgrade Oracle Database 12.1.0.2 to 19c. Database server’s OS is OEL 6.8 but oracle database 19c is not certified on OEL 6.8. So need to upgrade OS from version 6.8 to 7.6.

Continue reading

Sep 27 2020

How Oracle Database Processes DML Internally

Result set rows can be fetched either a row at a time or in groups. In the fetch stage, the database selects rows and, if requested by the query, orders the rows. Each successive fetch retrieves another row of the result until the last row has been fetched. DML-Operation. Insert a Record into a Table. …

Continue reading

Sep 26 2020

How Oracle Database Process Select Query Internally

This topic will describe how Oracle works internally with Index and Full Table Scan. Full Table Scan (No Index) when all blocks are available in Buffer Cache. Full Table Scan (No Index) when Blocks are not available in Buffer Cache. Select query Using index when get block from index and table segments. Select query Using …

Continue reading

Sep 19 2020

V$ View & Data Dictionary View on Oracle

Dynamic Performance (V$) Views: The Oracle Server contains a set of underlying views that are maintained by the server and accessible to the database administrator user SYS. These views are called dynamic performance views because they are continuously updated while a database is open and in use, and their contents relate primarily to performance. Data Dictionary View: …

Continue reading

Sep 19 2020

Oracle Real Application Cluster (RAC) Important Components

In this topic, I will demonstrate Oracle RAC components. SCAN IP VIP IP SCAN Listener Cache Fusion Cluster Interconnect RAC 2-way Global Cache Transfer RAC 3-way Global Cache Transfer Cache Coherency Global Cache Services (GCS) Global Resource Directory (GRD) Global Enqueue Services (GES)

Continue reading

Sep 18 2020

After Revoked Tablespace Quota From User in Oracle

In topic, I will descript how Oracle handle once we revoke tablespace quota from user. Once blocks assigned to a segment, even after revoked the Tablespace quota and deleted records from table, all allocated block will remain mapping with segment until we released block by using Shrink. This is the one good reason to release …

Continue reading

Sep 02 2020

Unused or Drop Column? Which option should use?

Sometimes DBA got request to drop the table’s columns. Oracle has following options to complete this task. Logical Delete. Physical Delete. Claim space for logical delete columns. Claim space for Physical delete column. Conclusion. In this article, I will discuss which option is more appropriate for big size of table. For small table, even physical …

Continue reading

Sep 01 2020

Oracle RAC Cache Fusion

Until Oracle 8i released, Oracle Introduced Parallel Server on Oracle 6i version. Oracle Introduced Real Application Cluster concept on Oracle 8i version. Oracle Cache Fusion is one of the important component in Oracle RAC environment. What is Cache Fusion How Cache Fusion works? How Oracle RAC read block from disk or buffer of another Instance …

Continue reading

Aug 30 2020

Oracle Database 19c Installation On Oracle Linux 7.1

I will describe the installation process of Oracle 19c (19.3) Database on Oracle Linux 7.1 on VM. 1. Create VM. 2. Software Download. 3. Install Oracle Linux 7.1 on VM. 4. Oracle Database Installation Prerequisites. 5. Oracle Database Software Installation. 6. Create a Container Database Using DBCA. 7. Create a Non-container Database Using DBCA. 8. …

Continue reading