What is reorg in DB2?

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.

How do you reorg a tablespace?

Manual Tablespace Reorganization

1. Create a new tablespace.
2. Move the segments to the new tablespace.
3. Drop the original tablespace.
4. Rename the new tablespace to match the original name. *

What is the need of using reorg utility?

The REORG TABLESPACE online utility reorganizes a table space to improve access performance and to reclaim fragmented space. In addition, the utility can reorganize a single partition or range of partitions of a partitioned table space. You can specify the degree of access to your data during reorganization.

What is a mapping table for a DB2 Reorg?

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.

How do I know if my table needs reorg?

An asterisk indicates that a table reorg is needed for that table, based on the results of that specific query.

1. F1. F1 is described in the reorgchk header as: F1: 100 * OVERFLOW / CARD < 5.
2. F2. F2 is described in the reorgchk header as:
3. F3. F3 is described in the reogchk header as:

What is offline reorg in DB2?

reorg table employee You can reorganize a table using a specific temporary table space. For example: reorg table employee use mytemp You can reorganize a table and have the rows reordered according to a specific index.

How do I get rid of undo tablespace?

Drop Unused UNDO Tablespace First, get a list of all the datafile for your UNDO tablespace. select file_name from dba_data_files where tablespace_name = ‘UNDOTBS’; Next, drop those data files one by one using alter tablespace drop datafile command as shown below. Now, drop the UNDO tablespace.

What is the use of table reorg in Oracle?

REORG PROCESS Reorders the table data according to the primary key index. The column reordering can be very useful for tables that have 300+ columns many of the columns are null. When the null columns are pushed to the end of the row, the read operation becomes streamlined thus increasing performance.

What is reorg tablespace?

The REORG TABLESPACE online utility reorganizes a table space, partition, or range of partitions to reclaim fragmented space and improve access performance. You can also run REORG TABLESPACE to materialize pending definition changes.

Which options of the reorg utility can be used to materialize pending changes to a table space?

To materialize pending data definition changes, use the following approaches: Run the REORG TABLESPACE utility with SHRLEVEL REFERENCE or SHRLEVEL CHANGE. Do not specify FASTSWITCH NO. Also note the restrictions for REBALANCE and AUX NO in Syntax and options of the REORG TABLESPACE control statement.

What is Reorg and Runstats in DB2?

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.

What is Runstats DB2?

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.

Is it possible to reorganize dsndb01.sysutilx?

You cannot reorganize DSNDB01.SYSUTILX. If SHRLEVEL NONE is specified, the UNLOAD ONLY or UNLOAD EXTERNAL and LOG YES options are not allowed for catalog and directory table spaces. However, LOG YES is required if SHRLEVEL NONE is specified for the catalog LOB table spaces. If SHRLEVEL REFERENCE is specified, LOG NO must be specified.

Do you need to reorg the catalog and directory?

The FASTSWITCH YES option is ignored for catalog and directory objects. You do not need to run REORG TABLESPACE on the catalog and directory table spaces as often as you do on user table spaces. RUNSTATS collects statistics about user table spaces, which you use to determine whether a REORG is necessary.

How to reorganize the dsndb06.systscpy table space in DB2?

When you reorganize the DSNDB06.SYSTSCPY table space with the LOG NO option and omit the COPYDDN option, Db2® places the table space in COPY-pending status. Take a full image copy of the table space to remove the COPY-pending status before continuing to reorganize the catalog or directory table spaces.

How often do I need to reorganize my DB2 catalog?

However, Db2 does not generate statistics for certain items in the directory, such as the SYSLGRNX table space and its corresponding indexes DSNLLX01 and DSNLLX02. Reorganize the whole catalog before a catalog migration or once every couple of years.