Best Practices for Filters
SAS Visual Data Builder
provides the
Where and
Having tabs for filtering data. Follow these
best practices:
-
Filter on the Where tab
first because the WHERE clause reduces the rows to consider for further
subsetting.
-
When you specify a filter on a column that is an index or
primary key, avoid using a function whenever it is possible. Using a function, such as
CAST(order_id
as DOUBLE)
, risks performing a full-table scan rather
than using the index.
-
In some cases, you can improve
performance by filtering on the table that has the smallest number
of rows first.
-
If you must remove a table that
is used on the Where or Having tabs,
then remove the reference to the table from the filters before you
remove the table. Otherwise, if you remove a table that is referenced
in a filter, then all of the filtering conditions are cleared.
-
When adding a
subquery using the
Libraries tab, an additional step is needed if the column names or table names are written
in a language that uses a
double-byte character set. After you finish adding the columns, you must manually enter an n-literal to
the
string on the
Code tab for each column name or table name that uses a
double-
byte character set. For example:
'table-name'n.'column-name'n
For
more information about editing code manually, see
Customizing Code.
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Last updated: January 8, 2019