Db2- Tablespace
Enviado por oscar86c • 19 de Agosto de 2013 • 304 Palabras (2 Páginas) • 227 Visitas
The DB2 database uses tablespaces. From a logical point of view, a tablespace
holds database objects, such as tables and indexes. On disk, a tablespace consists
of one or more data files, known as containers. The capacity of a tablespace can
be increased by adding containers to it.
With <SAPSID> being PRD, the SAP naming convention for tablespace names is
PRD#<tablespace_name><extension>.
The abbreviations in the tablespace name are part of the container name.
Containers are numbered starting with 000. A full path specification for a DB2
container for SAP system PRD would be:
/db2/PRD/sapdata1/NODE0000/PRD#BTABD.container000 (UNIX)
h:\db2\PRD\sapdata1\NODE0000\PRD#BTABD.container000 (Windows)
Hint: Note: The SAP system and SAP tools (such as SAP Storage
Management in ST04) suggest that the naming conventions be observed.
Following the SAP naming convention ensures fast and efficient support
from SAP.
2005/Q4
Figure 30: SQL Statement Processing (2)
This example shows the processing when an SQL statement is executed that
changes data:
1. Statements that will alter data such as UPDATE/INSERT/DELETE SQL
statements are sent from the SAP application to the associated DB2 agent.
2. The DB2 page holding the data is altered in the buffer pool. Much later, it
will be transferred to disk. At the same time, the DB2 agent process writes
information about the changes to the data to the log buffer. DB2 uses the
log records for this write operation.
3. The db2loggw process is responsible for writing the contents of the log
buffer to the current active log file. This is done when an application ends
the transaction by issuing a COMMIT SQL statement, every second, and
when the log buffer is full.
4. I/O cleaners or page cleaners copy updated pages to disk when triggered. I/O
cleaners get triggered when:
The maximum amount of log space that should be read during crash
recovery has been reached (DB CFG parameter SOFTMAX)
The maximum percentage of changed pages has been reached (DB
CFG parameter CHNGPGS_THRESH)
No pages are available during insert/update. In this case, victim page
cleaning is started.
...