Table of Contents
What is reorg in DB2?
The DB2 reorg command reorganizes the table and its indexes by rebuilding the index data into unfragmented and contiguous area on the disk. This operating requires locking the data for movement. If there are applications that access this data, then the application performance might be degraded.
What is explain in DB2?
The EXPLAIN statement obtains information about access path selection for an explainable statement . A statement is explainable if it is a SELECT, MERGE, TRUNCATE, or INSERT statement, or the searched form of an UPDATE or DELETE statement.
Why reorg is required?
To keep it simple: REORG is a database operation that is executed in DB2 to reorganize the table spaces or index spaces. The purpose of the reorganization is data clustering. This operation reconstructs the data in the table spaces or index spaces, so that the data is unfragmented and physically continuous.
What is FlashCopy in DB2?
You can configure certain utilities to create image copies by using the FlashCopy® function that is provided by z/OS® DFSMS and the IBM® TotalStorage ESS storage subsystems. FlashCopy can reduce both the unavailability of data during the copy operation and the amount of time that is required for recovery operations.
How does reorg work in DB2?
What is the use of reorg in DB2?
What is Shrlevel change?
Log processing with SHRLEVEL CHANGE When you specify SHRLEVEL CHANGE, Db2 processes the log to update the shadow copy. This step executes iteratively. The first iteration processes the log records that accumulated during the previous iteration.
How do you plan a reorg?
We highly encourage you to contact our HR office so that we can assist you through these steps.
- STEP 1 – Define the Problem. • Determine whether existing jobs and structures are meeting department goals.
- STEP 2- Identify New Structure.
- STEP 3- Develop a Reorganization Proposal.
- STEP 4- Create a Communication Plan.
How to install Db2 on Windows 10?
About this task. You cannot have more than one instance of the DB2 Setup wizard running in any user account.
How to truncate table in DB2?
you can use following command which will perform same operation as truncate in DB2 “Alter table table_name activate not logged initially with empty table”. Logging will not happen in this command, while in delete logging will be done. You can’t rollback in this kind of truncate and you can rollback in delete.
Does DB2 sort an empty resultset?
The ASC or DESC is optional. If you skip it, Db2 will use ASC by default. When evaluating the SELECT statement with an ORDER BY clause, Db2 evaluates the clauses in the following order: FROM, SELECT, and ORDER BY. In other words, Db2 always evaluates the ORDER BY clause at last.
What is REORG in DB2. To keep it simple: REORG is a database operation that is executed in DB2 to reorganize the table spaces or index spaces. The purpose of the reorganization is data clustering. This operation reconstructs the data in the table spaces or index spaces, so that the data is unfragmented and physically continuous.