NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
S-58
Similarity Between Collations
Tables referenced in the position of tablea in the following statements can be similar,
but tables referenced in the position of tableb in the following statements can never
be similar:
SELECT columnx FROM tablea
WHERE EXISTS SELECT [DISTINCT] * FROM tableb;
SELECT tableb.*, tablea.x FROM tableb, tablea;
Similarity Between Collations
Collations that are explicitly referenced in an SQL query are similar only if they are
equal. SQL uses the procedure CPRL_COMPAREOBJECTS_ to determine equivalence
of collations.
SLACK File Attribute
SLACK is a file attribute that specifies the minimum percentage of space to leave for
future insertions when loading data and index blocks. SLACK applies only to key-
sequenced files and to indexes.
percent
is an integer from 0 to 99 that specifies the percent of empty space to leave in each
data and index block during loading.
The default is 15 percent.
Purpose of SLACK
•
SLACK specifications are usually between 15 and 25 percent.
•
Specifying a larger than normal SLACK value when a file is initially loaded and
many more inserts are expected can improve performance by reducing the number
of block splits required when inserts occur.
•
For a file expected to have little activity, you can save disk space by specifying a
smaller than normal SLACK value.
SPACE Option
SPACE is an option of the SQLCI report writer SET LAYOUT command that specifies
the default number of spaces between columns of report print items. Each space
occupies a single byte position, regardless of the character set in use.
SLACK percent
SPACE number