SQL/MX 3.x Reference Manual (H06.22+, J06.11+)

Metadata Tables
HP NonStop SQL/MX Reference Manual—640322-001
10-49
Function Control
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
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.
ANSI_STRING_FUNCTIONALITY This CQD determines whether the behavior of SQL
string functions is in accordance with the ANSI
standards.
When set to ON, the SQL string functionality is in
accordance with ANSI standards. When set to OFF,
the SQL string functionality might not be according to
ANSI standards.
This CQD is applicable only for the LPAD and RPAD
string functions. For more information about these
functions, see LPAD Function
on page 9-85 and
RPAD Function on page 9-132.
The default is OFF.
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 10-51 also
relates to histogram caching.
The default is ON.