SQL/MX 2.x Reference Manual (H06.04+)

Metadata Tables
HP NonStop SQL/MX Reference Manual—540440-003
10-41
Data Types
Data Types
This attribute controls whether the output of dynamic SELECT statements and dynamic
parameters that are FLOAT data types should be treated as Tandem FLOAT format or
IEEE FLOAT format:
Function Control
This attribute controls how NonStop SQL/MX handles functions:
Histograms
These attributes enable NonStop SQL/MX to improve performance of query execution
by ensuring defaults for histogram statistics:
Attribute Setting
FLOATTYPE Set to IEEE or TANDEM.
The default is TANDEM.
Attribute Setting
PRESERVE_MIN_SCALE An arithmetic operation on numeric columns might
give a wrong result. If the result value exceeds the
allowed numeric limit, the precision is truncated to
18.
PRESERVE_MIN_SCALE allows you to preserve
minimum scale in a result when the precision
exceeds 18.
Allowable values: 0 to 18
The default is 0.
Attribute Setting
CACHE_HISTOGRAMS Set to ON or OFF. When set to ON, NonStop SQL/MX
caches the histogram so that it can be retrieved from the
cache rather than from the disk for future queries on the
same table. Histogram caching provides faster access to
histograms. This attribute significantly reduces compile
time for less complex queries.
If OFF, histograms cached previously are flushed from
cache, and histograms for every query are loaded from
the disk. When CACHE_HISTOGRAMS is turned ON
again, histograms are reloaded, and NonStop SQL/MX
caches them again.
The attribute HIST_PREFETCH
on page 10-43 also
relates to histogram caching.
The default is ON.