TUNING OWB

use the Key Look up operator to look up data from a table, view, cube, or dimension. For example, use the Key Look up operator when you define a mapping that loads a cube or when you define surrogate keys on the dimension.

The key that you look up can be any unique value. It need not be a primary or unique key, as defined in an RDBMS. The Key Lookup operator reads data from a lookup table using the key input you supply and finds the matching row. This operator returns a row for each input key. You can have multiple Key Lookup operators in the same mapping.

The output of the Key Lookup operator corresponds to the columns in the lookup object. To ensure that only a single lookup row is found for each key input row, use keys in your match condition.

Each output attribute for the key lookup has a property called DEFAULT VALUE. The DEFAULT VALUE property is used instead of NULL in the outgoing row set if no value is found in the lookup table for an input value. The generated code uses the NVL function. The Key Lookup always results in an outer-join statement.

USING KEY LOOKUP OPERATOR

What is key lookup operator

As the name implies its purpose is to lookup data.

Its used to lookup data from table view cube dimension 

The key lookup operator reads data from a lookup table using the key input and find matching row.

When ?

How ?


You have the following options for using a key lookup operator:

Define a new key lookup operator: drag a key lookup operator from the palette onto the mapping. The mapping editor displays a wizard.

Edit an existing key lookup operator: right-click the key lookup operator and select open details.

Whether you are using the operator wizard or the operator editor, complete the following pages:

General
groups
input connections
lookup
type 2 history lookup
no-match rows
general

Use the general page to specify a name and optional description for the key lookup operator. By default, the wizard names the operator "key_lookup".

Groups

Use the groups page to specify one input and one output group.in a key lookup operator, the input group represents the data from the source that is contained across multiple attributes. The output group represents that data transformed into rows.you can rename and add descriptions to the input and output groups. Since each key lookup operator must have exactly one input and one output group, the wizard prevents you from adding or removing groups or changing group direction.

Input connections

Use the input connections page to copy and map attributes into the key lookup operator. The attributes you select are used to perform a lookup on the lookup object and find matching rows. The left side of the page displays a list of all the operators in the mapping.