Best Practices for Filters

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.

Filter 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 in a language 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.