15.00 - DisableMergeBlocks - Teradata Database

Teradata Database Utilities

Product
Teradata Database
Release Number
15.00
Content Type
Configuration
Publication ID
B035-1102-015K
Language
English (United States)
Last Update
2018-09-25

DisableMergeBlocks

Purpose  

Determines whether the file system automatically merges data blocks together on storage cylinders during full table modify operations. Merging several small data blocks into a single larger block can improve system performance by reducing disk I/O.

Field Group

File System

Valid Settings

 

Setting

Description

TRUE

Automatic merging of data blocks is disabled.

FALSE

Automatic merging of data blocks is enabled.

Default

FALSE

Changes Take Effect

After the DBS Control record has been written.

Usage Notes  

During normal database operations, the data blocks that store table rows on cylinders can split and shrink, resulting in many blocks which are far smaller than the maximum allowed data block size. Full table modify operations for tables with several small data blocks require more disk I/O than would be required if the table rows were stored on fewer and larger data blocks. Teradata Database can merge the small data blocks of these tables automatically during full table modify operations, which can result in reduced I/O overhead and improved database performance.

Data block merging applies only to permanent and permanent journal tables.

If DisableMergeBlocks is TRUE, the MergeBlockRatio setting is ignored.

Related Topics

 

For more information on...

See...

Setting the maximum size of merged data blocks

“MergeBlockRatio” on page 381.

the MERGEBLOCKRATIO option of CREATE TABLE and ALTER TABLE

SQL Data Definition Language.