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.Also, what is Reorg and Runstats in db2?
runstats and reorgs. runstats is for collecting indexes and tables statistics information which to enable the DB2 optimizer to generate efficient access plan. reorgs is for reorganizing tables and indexes.
Additionally, what is explain in db2? EXPLAIN tables contain information about SQL statements and functions that run on Db2 for z/OS®. Db2 creates EXPLAIN output and populates EXPLAIN tables in the following situations: When an EXPLAIN statement is executed. At BIND or REBIND with the EXPLAIN(YES) or (ONLY) bind options.
In respect to this, what is online reorg in db2?
Online Reorg is an availability enhancement to DB2 introduced in DB2 Version 5. It increases availability of a tablespace and/or index while it is being reorganised. The reorganisation of an object necessarily consists of the destruction of an object and its rebuilding in reorganised form.
What is Runstats db2?
Runstats is a utility in Db2 that is used to collect statistics about the data in Db2 tables and indexes. This statistical information is critical to Db2 database performance. Runstats is executed on a table by table basis, so scripting it is quite common.
What is Dclgen?
DCLGEN (Declaration Generator) is a structure-generating utility that maps the columns of a database table into a structure (a COBOL record) that can be included in an embedded SQL declaration section.What is null indicator in db2?
The null indicator is used by DB2 to track whether its associated column is null or not. A positive value or a value of 0 means the column is not null and any actual value stored in the column is valid. If the value is -2 then the column was set to null as the result of a data conversion error.What is image copy in db2?
DB2 Image Copy. This is something done by using DB2 utility and by your DataBaseAdministrator . This process of taking full back-ups of your data objects is called as DB2 full image copy. It is achieved by DB2 utility COPY. You can make full image copies of a variety of data objects.What is a db2 plan and package?
A package contains control structures that DB2® uses when it runs SQL statements. An application plan relates an application process to a local instance of DB2 and specifies processing options. You can think of the control structures as the bound or operational form of SQL statements.What is index in db2?
Index is a set of pointers, which can refer to rows in a table, blocks in MDC or ITC tables, XML data in an XML storage object that are logically ordered by the values of one or more keys. It is created on DB2 table columns to speed up the data access for the queries, and to cluster and partition the data efficiently.What is database reorg?
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 mapping table in db2?
Mapping tables If you run REORG TABLESPACE with SHRLEVEL CHANGE, the utility uses a mapping table to store the source and target RID for each row. REORG can implicitly create this mapping table. Alternatively, you can create it yourself.Why do we bind in db2?
DB2 Bind compiles all your sql statements(dbrm) into an executable format. It uses DB2 Optimizer to create the better access path. This explains you very clearly about,precompilation,Bind,packages,plan etc etc details.What is difference between plan and package?
The main difference between Plan and package lies with the time. Remember, Plan does have the "member list" of the DBRMs in the programs of an application. Plan / package contain the run-time instructions for the SQL statements in the program.What is bind process in db2?
In DB2, the “compile” process is called BIND, and the “load module” is called a PACKAGE. BIND is to your DBRM what COMPILE is to your COBOL. BIND must take your source code (the SQL) and turn it into executable code (a PACKAGE). During this step the DB2 Optimizer will turn our SQL into executable code.What is access path in db2?
The access path for an SQL statement specifies how DB2 accesses the data that the query specifies. It specifies the indexes and tables that are accessed, the access methods that are used, and the order in which objects are accessed. DB2 selects the access paths for dynamic SQL statements when the statements are issued.What is db2 Optimizer?
The DB2 optimizer is a cost-based optimizer, which means it makes decisions based on statistics that are available for the tables and indexes. When generating statistics, DB2 offers the possibility to create so-called distribution statistics in addition to the basic statistics.What is uncommitted read in db2?
Since V4, DB2 has provided read-through locks, also know as “dirty read” or “uncommitted read,” to help overcome concurrency problems. When using an uncommitted reads an application program can read data that has been changed, but is not yet committed.What is db2 mainframe?
DB2® for z/OS® is a relational database management system that runs on the mainframe. DB2 is software that you can use to manage relational databases. IBM® offers a family of DB2 products that run on a range of operating systems, including Linux, UNIX, Windows, IBM i, VSE, VM, and z/OS.What is Runstats utility in db2?
DB2 RUNSTATS utility. RUNSTATS is a DB2 utility that scans a table space or indexes to gather information about space utilization and index efficiency. The information gathered is stored in the DB2 system tables and used by the SQL optimizer to select the best access paths during the bind process.What is isolation level in db2?
One of the ways DB2 enforces concurrency is through the use of isolation levels, which determine how data accessed and/or modified by one transaction is "isolated from" other transactions. DB2 recognizes and supports the following isolation levels: Repeatable Read (RR) Read Stability (RS) Cursor Stability (CS)What is load and unload in db2?
Unloading and loading tables. When you need to change a DB2 table, for example by adding a column, you can save the existing data by using the DB2 Unload utility. The data set used for the Load utility can be read from both disk and tape. The Unload utility is used to unload data from a table to a sequential data set. 
