NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
B-12
BUFFERED File Attribute
Before the first detail line is printed, and each time the value of DEPTNUM
changes, the break title defined in the following command appears in the report:
S> BREAK TITLE D.DEPTNUM
+> ( CONCAT (DEPTNAME STRIP, " Department") );
S> LIST NEXT 8;
DEPTNUM EMPNUM JOBCODE
------- ------ -------
FINANCE Department
1000 23 100
202 500
208 900
210 500
214 500
PERSONNEL Department
1500 209 900
211 600
212 600
BUFFERED File Attribute
BUFFERED is a Guardian file attribute that specifies whether to buffer writes to a disk
file. BUFFERED applies to key-sequenced, relative, and entry-sequenced tables, and to
indexes.
The default for an audited table is BUFFERED. The default for a nonaudited table is NO
BUFFERED. The index default is the table value at index creation.
Considerations—BUFFERED
•
How buffering works
All retrieved rows are stored in cache memory temporarily. In a NO BUFFERED
file, a block that contains an updated row is written to disk immediately. In a
BUFFERED file, a block that contains an updated row is not written to disk until a
system event (such as the need for more cache memory) triggers a write. An updated
block can change more than once without the need for writing each change to disk
as the change occurs.
•
Danger in buffering nonaudited files
{ BUFFERED | NO BUFFERED }