User Guide

SAP AG November 2002
• Isolation Level 3 or 30 [Page 118] (serializable)
Kernel
The threads [Page 151] of a database instance [Page 132] are often referred to as the kernel.
Language Support (MapChar Sets)
A MapChar set is a character string that maps language-specific characters to the ASCII code
or EBCDIC code. This character set is only of any significance for internal system functions.
MapChar sets were introduced to allow letters to be converted. MapChar sets enable country-
specific letters to be mapped to one or two non-country-specific letters (for example,
representation of "ü" as "ue").
When the database instance is configured, a conversion of these country-specific letters is
implicitly allowed and stored under the name DEFAULTMAP. The DEFAULTMAP conversion
definition can be changed.
Further MapChar sets can also be defined with the Database Manager.
For example, the MapChar set is used by the MAPCHAR SQL function to sort fields
containing umlauts.
With the Database Manager, you can create, display, change, or delete MapChar sets
(Database Manager GUI: SAP DB 7.4 Sections Creating MapChar Sets [See SAP DB
Library], Displaying, Changing and Deleting MapChar Sets [See SAP DB Library]).
See also:
Reference Manual: SAP DB 7.4, Sections ASCII Code [See SAP DB Library]
, EBCDIC Code
[See SAP DB Library], MAPCHAR(x,n,i) [See SAP DB Library]
liveCache
liveCache is a database instance type [Page 132] of the SAP DB database system.
In Supply Chain Management, large volumes of data must be permanently available and
changeable. For this reason, an addition has been made to the SAP DB OLTP [Page 149]
relational database system to enable actual data structures and data flows (such as networks
and relationships) to be mapped more easily and effectively. The product is called liveCache.
The liveCache is object-oriented, and in contrast to SAP DB OLTP, stores its data in the main
memory of the database system.
Lock
The lock behavior [Page 113] depends among other things on the type of lock. Tables and
rows are locked in a transaction [Page 152] with a defined lock mode (Requesting and
Releasing a Lock [Page 115]).
The database system differentiates between the following locks:
Shared lock [Page
114]
•
User Manual: SAP DB 140